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700 Section 2 (28) Ignition systems

1. Ignition timing BTDC with vacuum advance unit disconnected Engine type 12 5 rls 41 7 rls 750 rlmin 2500 r min B19E 10 28 33 819ET 15 23 26 B23E O 28 33 B23ET 10 B23FT 12 2 B200K 15 22 26 B200E 1221 23 27 B200ET 14021 6 B204 15 9 B230A T 17 23 B230K 15 27 31 B230E 1221 23 27 B230ET 10021 6 B230F 12 B230F 10 B230FT 12 20 40 B234F 15 B28A 10 25 29 B28E 1021 25 29 B28F 23 B280E 1099 B280F 169 At idling 14 1 ris 850 r min 2 At 15 ris 900 r minl 3 At 13 3 ris 800 r min o At 15 rls 900 r min for Japan s AC system disconnected i Not adjustable 11 Rex I Specifications Group 28 Ignition systems Specifications Ignition coil Primary winding resistance across terminals 1 and 151 819E B19ET B23E B23FT B230A 0 6 0 90 B23ET 0 50 B28 0 50 B 200 E 8 200K B 230 E B230 F B 230K B230 FT B280 B204 E B234F 0 6 0 90 B2OOET B230ET 0 50 B230F Rex I 0 35 0 650 Secondary winding resistance across terminal 1 and HT termi nail B19E B19ET B23E B23fT B230A 6 5 8 5 kO B23ET 6 0 kO B28 9 5 kO B 200 E B200 K B 230 E B230 F B 230 K B230 FT B280 B204 E B224P s 6 5 9 0 kO B200ET B230ET 6 0 kO B230F Rex Ill 2 0 8 ll eee eee EEE OEE T 4 6 kQ Spark plugs 306 604 8 273 596 7 306 604 8 273596 7 306 604 8 273596 7 1 306 605 5 273 597 5 1 1
2. This manual deals with the following engine variants Engine Model year s Engine Model year s 819 E 1984 B 230 FT 1985 B 23 E 1984 B 230 K 1985 B 23 FT 1984 88 B 200 E 1985 B 28 A 1982 85 B 200 K 1985 B 28 EIF 1982 86 B 280 EIF 1986 B 230 A 1985 86 B 204 E 1989 8230E 1985 8234F 1988 B 230 F 1985 Volvos are sold in versions adapted for different markets These adaptations depend on many factors including le gal taxation and market requirements This manual may therefore show illustrations and text which do not apply to cars in your country Volvo owners planning to export their car s to another country should investigate the applicable safety and ex haust emission requirements In some cases it may be im possible to comply with these requirements Group 28 Ignition systems Group 28 Ignition systems Contents Page Introduction 3 Design and function Overview Review of electronic ignition systems uuellllussss Sire RR Ed 4 Review of electronic ignition systems Il type EZ K and Rex l 6 General Function of ignition system combustion theory in brief 2 2 lssuuu 9 Ignition systems basic parameters 0c cece ee eee eee dd Contact breaker versus electronic systemMS 00eeeee2 ee Msi Sid tees 13 Components Gontrol unite 52 eio dees tah oe use wt die Ue oh eee eee 14 Control unit power stage and ignition coil
3. 270479 9 1984 275688 0 1984 275689 8 275689 8 1984 1984 270748 7 1985 270749 5 1985 87 270 897 2 1988 270880 8 1988 2704787 1985 270 560 6 1985 87 270 561 4 1985 87 270 561 4 1985 87 Group 28 Ignition systems Specifications B230K 270748 7 1985 871 270 896 4 1988 270748 7 1985 87 270896 4 1988 B230E 270748 7 1985 871 270 896 4 1988 B230ET 270749 5 1985 87 270 897 2 1988 B230F 270748 7 1985 87 270 896 4 1988 B230FT 270749 5 1985 871 270 897 2 B234F 270880 8 1988 1 B280E 270525 9 1985 1 B2BOF 270525 9 1985 1 1988 Ranix F 8200K 1986 B200K 1987 1 367 072 4 1 13895339 533 9 Speed positi on pick up 1 336660 4 1 336 660 4 TZ 28H B19E B19ET 8 23E B230A 1 389939 8 1389 939 8 1 389 939 8 1 389 939 8 EZ 102K Control unit 1 332 580 8 Power stage 1 332 584 0 Knock sensor 1 326658 0 Throttle switch 1 306 939 0 77 Group 28 Ignition systems Specifications EZ 115K Engine B2BOE B2BOE B2BOF Scandinavia Control unit 1 274 827 3 1 389 597 4 1274828 1 Power stage 1 332 584 0 1 332 584 0 1 332 584 0 Knock sensors 1367 643 2 1 367 643 2 1 367 643 2 Temperature sensa 1 346 030 8 1 346 030 8 1346030 8 Throttle switch 1 306 938 0 1 306 938 0 1306938 0 Speed position pick up 1 367 645 7 1 367 645 7 1 367 645 7 No 1 cylinder detector 1 367 188 8 1367 188 8 1 367 188 8 E
4. Reading should be 0 6 0 9 ohm Other reading Ignition coil faulty or short circuit in leads Measure resistance directly between ignition coil ter minals 1 and 15 If resistance is correct 0 6 0 9 ohm Fault in lead be tween ignition coil and connector If resistance is incorrect Replace ignition coil H5 Check ignition coil secondary winding Measure resistance between HT terminal and terminal 1 on ignition coil Resistance should be 6 5 8 5 kohm Other reading Ignition coil faulty Replace coil Group 28 ignition systems Fault tracing EZ 102K H6 Check power stage ground lead 2 Measure resistance between connector terminal 2 and ground Resistance should be 0 ohm If reading is different Check lead see wiring diagram Ground terminal is on intake manifold H7 Check screen connections Check that screen of lead to terminal 5 is connected to 3 terminal 3 o H8 Check signal from control unit to power stage Disconnect leads from ignition coil terminal 1 red white and 15 bluel 5 Measure voltage between terminal 5 or 6 in power stage connector and ground Operate starter motor Voltmeter should indicate approx 2 V No reading See top of page 146 Reconnect coil leads T Reconnect power stage connector Undo distributor connector Switch on ignition Mea sure voltage between positive terminal red lead and ground Reading should be approx 12 V 139 117K Ignition system 823
5. Temperature compensation of the timing on a hot engine means advancing the timing to reduce the coolant temper ature This prevents the engine from boiling although the cooling water will not begin to boil while the temperature is below approx 120 125 C due to the fact that the system is pressurized The timing advance is normally applied only when idling since the setting is normally fairly retarded under these conditions 42 Group 28 Ignition systems Design and function System descriptions mo a 16 31d 7 31 TSZ B28AJEJF TSZ is a type of electronic ignition system in which an inductive pulse generator performs the function of the contact points Roughly translated the abbreviation TSZ means Transistorized coil ignition The pulse generator transmits information to a control unit which controls the charging period of the ignition coil The system also incorporates a centrifugal generator and a ballast resistor The variant used on 6 cylinder engines 8 28A1E FI is designated TSZ 4 and is used on 1982 86 700s 43 Group 28 Ignition systems Design and function System descriptions 210 0 5 6 3 4 2 1 0 TZ 28H TZ 28H B19E1ET B23E B230A The control unit 210 consists of a number of electronic circuits operating a power circuit which controls the pri mary current in the ignition coil The control unit interrupts the current on receipt of an ignition pulse from the Hall ge
6. 0 37 Specified number of engine revolutions depending on speed EZ 118K Ilvalues for B230K 1985 86 8230E and B200E respectively Max knock controlled retardation Knock retardation step Re advance step Re advance interval revolutions depending on speed EZ 115K Max knock controlled retardation Knock retardation step Re advance step Re advance interval EZ 116K Max knock controlled retardation Knock retardation step Re advance step Re advance interval Rex Max knock eontrolled retardation Knock retardation step Re advance step Re advance interval 15 16 9 8 12 6 2 8 2 8 8 7 depending on speed 2 8 2 8 0 35 in all cases Specified number of engine 11 15 depending on variant 3 0 37 Specified number of engine revolutions depending on speed 14 2 6 at n lt 4895 r min and 2 3 at n gt 4895 rfmin 0 375 Specified number of engine revolutions depending on speed 15 3y at n gt 4895 r min Specified number of engine revolutions depending on speed 33 Group 28 Ignition systems Design and function Compensation functions cy REX I 147 097 Rex I On the Rex l system the program functions which control the tendency of the engine to knock are somewhat differ ent to those in the EZ K systems The differences are described in the following pages Knock characteristic The figure shows the normal ignition setting a assuming in
7. 5 kohm N28 Check for voltage at ignition coil power stage terminals Switch on ignition Measure voltage between terminal A in 3 pole connec tor and ground Instrument should indicate system voltage 12 VI voltage is absent or I too low Check supply lead connections at control unit and ignition coil power stage Check that voltage does not fall below 10 5 V when starter motor is operated Switch off ignition 223 Group 28 Ignition systems Fault tracing Rex l m 146 729 146 729 B 0 ct 8L RW umm RN S iE 224 N29 Check ignition coil power stage ground connec tions Measure resistance between terminal B in 3 pole con nector and ground Resistance must not exceed 0 1 ohm If resistance is too high clean ground connection and or replace ground lead as required Measure resistance between terminal A in 2 pole con nector and ground Clean ground connection and or re place ground lead as required if resistance exceeds 0 1 ohm N30 Check signal lead between ignition coil power stage and control unit Connect buzzer between terminal B in 2 pole connec tor and terminal 16 in control unit connector Buzzer should sound if lead is intact N31 Persistent failure of engine to start despite absence of faults or correction of fault s which have been located indicates internal fault in control unit or power stage Verify by installing new control unit or new power stage Reinstall i
8. Picture B Power is supplied to control unit terminal 6 across ignition switch terminal 15 when the key is turned to position II Voltage is present at terminal 1 on the control unit when the coding cable is inserted in socket No 6 on the diagnostic unit Signal from diagnostic unit Picture CI The control unit must be supplied with some type of signal indicating which of the test functions is to be activated This information is supplied across the normally open switch pushbutton A The direction of the arrows in this picture shows that the signal flows from the diagnostic unit to the control unit The switch is closed by depressing the pushbutton grounding terminalS on the diagnostic unit Current then flows from the battery across ignition switch terminal 15 through the diagnostic unit and finally to ground across terminal 8 This causes the LED to light while the voltage normally present at control unit terminal 1 falls to 0 V The control unit determines whether the self diagnostic function or functional test program has been selected by detecting whether the voltage at terminal 1 has fallen to zero once or twice 66 Group 28 Ignition systems Design and function System descriptions Signels to diegnostic unit Picture 0 In this mode the diagnostic circuit in the control unit reads the selected test function program and determines as ap propriate which fault acknowledgement code is to be displayed by the LED t
9. currenl and resistance measurement Ohmmeter diode tester for resistance measurement Volvo Mono Tester for measurement of timing angle Stroboscope for checking timing Plain text reader for displaying fault codes in plain text 132 977 Group 28 Ignition systems General instructions Instructions for work on ignition systems Identification No USA Canada bee eee ww om gt Resistance measurement All leads must be alsconnected from the terminals of items to be tested Specified values apply at approx 20 C 68 FI NOTE The expansion plug on 8 venically installed igni tion coil must be provided with a plastic cap Electronic ignition systems WARNING Electronic ignition systems operate at voltages in excess of 30000 V In addition the power developed is such that contact with live components may be potentially fatal The presence of a dangerous voltage is indicated by the UE The engine variant and model year are included in the type designation E Engine type 69 C a d Identification No other markets Model year Engine type Engine type 23 820CK 24 B19E B200E 26 819ET B20CH 62 828A 68 a28E B28aE 69 B28F B200F 7S 024TIC 76 024T 71 024 Model year c cex rommoao Model year YV1 744682C 1001234 69 Group 28 Ignition systems General instructions 70 Important Warning The ignition system operates at hi
10. rotor stator min 0 3 mm 0 1 8230A Bosch part No 0 ks eee eee eee eee esses 0237024013 Volvo part No 2 02sec eee eee ee ae at Se ee eee eee eee s 1336690 Direction of rotation 2s Clockwise Pulse generator coil resistance ohm e Air gap rotor stator MIN 2 2 73 Group 28 Ignition systems Specifications Centrifugal advance unit B19E B23E Total advance distributor degrees Advance commences at distributor speed r s r min Settings 5 at distributor speed r s Sir LUTEA es retra r mli s zx eet ers eremi OF ee esis eu 10 at distributor speed r s EAn LE Max advance at distributor speed ris r min V ELE B19ET Total advance distributor degrees SRG Advance commences at distributor speed r s minl 2 209 s Settings 5 at distributor speed r s Aad e inue CASE Mat MIN Seas oom epee ctr acerbe AE ENE 10 at distributor speed rs LIN HDD r minl Max advance at distributor speed ris DL ee fr min cE ee B28A E Total advance distributor degrees Advance commences at distributor speed ris r min Settings 5 at distributor speed ris illos Se Panes AMIN ches ee tS eed cle ewe ole LN PEE 10 at distributor speed r s MM LAE MEN QU min sac mele TEL TE ME M Max adv
11. 111 B19E B23E B28A B28F 95 Fault tracing Spark plugs 11 12 72 General procedures Sev 79 104 Fault tracing chart eee 104 Fault tracing procedures System Procedure i TSZ 4 El E23 106 114 Renix F FI F26 115 124 TZ 28H G1 G7 125 134 EZ I02K HI H21 135 150 EZ 115K Jl J45 151 168 EI 117 118K K1 K26 169 186 EZ 116K B234 F 8204 EJ LI L36 187 200 EZ 116K B230 F M1 M38 201 214 Rex I NI N31 215 226 Firing order 71 General instructions 69 Ground terminals TZ 28bl st ohana tas eU ee held visu 09 TSZ 113 BenbcE suus dADely eae het bed lu yi 115 EZ 102K Sus wh date Slr eee cx E T EZ 115K 161 EZ 117K1118K 171 zh PPM M eS a 189 203 PONG ls Z2 ates oe SS she ets 2l Speed position pick up 22 24 78 157 194 208 222 System descriptions TSZ 43 T2228 o cep ce ee oud Sates 44 Renix F e eco cove e e ese e iil 45 EZ 102K e e ses 47 EZ 117K etatem utt do cR 49 EZ 118K Serana 51 EZ 115K 55 EZ 116K 58 Rex 60 Temperature sensor 41 42 155 178 192 206 220 Test equipment 68 Throttle switch idling switch 40 146 156 177 193 207 221 Timing retardation B19E 86 Vacuum advance 75 76 85 Wiring diagrams JS AREE neces heen a M LOS ae on nir 113 114 Renix F oc 2 eee Oe Meee Oe Oe ss 123 124 TZ28H ee ee ee ee eue Loy LLL 133 134 EZ I02K Wm ciens eet rr 148 150 EZ 115K
12. 346 541 4 271 409 5 2699 15 3 273 599 1 2699 15 3 273 599 1 269915 3 273 599 1 367 528 5 270746 1 B200E 1 367 529 3 270 747 9 B200ET 8204 1989 8230A B230K 1986 B230 K 1987 8230FT Eur other 8234F 1988 8280E Nor other 8280F 1 367 528 5 1 367 529 3 1 367 528 5 1 306 605 5 1 306 604 8 1 367 529 3 1 367 528 5 1 367 528 5 1 367 529 3 1 367 528 5 1 367 529 3 1 269915 3 1 389 896 0 1269 915 3 Spark plug gap 819 823 8200 8 230 8234 F 8204 828 8280 Tightening torque unoiled plug 819 823 8200 8230 8234F 8204 828 8280 TEMPE 72 270746 1 270 747 9 270746 1 273 597 5 273 596 7 270 747 9 270746 1 270746 1 270 747 9 270746 1 270 747 9 273 599 1 270 590 3 273 599 1 0 7 0 8 mm 028 0021 0 6 0 7 mm 024 028 25 5 Nm 18 3 5 h fbi 12x 2 Nm 9 1 5 ft Ib Group 28 Ignition systems Specifications Distributor Engine Ignition system Distributor Volvo part No Bosch part No B19E B23E TZ 28 H 1 336 689 0237020075 B19ET TZ 28 H 1336 694 O 237 020 031 B23ET Motronic 1317298 O 237 501 003 B23FT EZ Kil 1332 587 0237506001 B200E B230K EZ KII 1 336 087 O 237 502 001 B230F Rex l EZ K 1336 132 0237502002 B230E B230 F B230FT EZ K i 1 336 087 0237 502 001 B200K Renix 1 336 132 0237502002 B200 ET B230ET Motronic 1336 132 0237502002 B230A TZ 28 H 1 336 690 0237024013 B28A B28E TSZ4 1269 191 0237402013 B28F TSZ 4 1 269
13. 380 0237402017 8280 EZ KH B204 8234F EZ K 1 367 197 9 0237502003 Microprocessor controlled System is not equipped with centrifugal or vacuum advance unit See test values below for other dis tributors 21 Modified distributors have same values as 1 336690 B230A B19E B23E Bosch part No suuuueluluull t ullus 0 eee eee ees 0237 020 075 Volvo part No eee eee eee eee Diewree e een see 1336 689 Direction of rotation 0 002 eset usus S Clockwise Pulse generator coil resistance ohm occa Air gap rotor stator min cede 819ET Bosch part NO iss 2c2 cc0c0 dnc ee iee cate cracas eee usss O 237 020 031 Volvo part NO eno mv DERE e E VD e rs 1336 694 Direction of rotation n Clockwise Pulse generator coil resistance ohm Air gap rotor stator min l l cee ee See ee eee 828A E Bosch part NO sss sccecesegnn E RRpES RE EUR TEE 0237 402 013 Volvo part INO serene nr sene er Ease E 1 269191 Direction of rotation Clockwise Pulse generator coil resistance ohm 540 660 Air gap rotor stator min Sus Tera 0 3 mm 01 828F Bosch part No iacens usse rs Sides 0237402017 Volvo part No cesse eme mef rie mec CERE 1 269 380 Direction of rotation 0 2 02 lll llle ee See uu LE Clockwise Pulse generator coil resistance ohm s 540 660 Air gap
14. 4 control unit 9 transmits engine load signals from the air mass meter Engine temperature is indicated by the temperature sensor 10 Closure of the throttle is indicated by the throttle switch 11 The control unit can vary the timing from approx 55 before TOC to approx 5 after TOC 58 Group 28 Ignition systems Design and function System descriptions DM 147 119 EZ 116K Control unit connections ONDAN Transmits signals to diagnostic unit 482 during fault tracing Receives analogue engine temperature signal from temperature sensor 84 Transmits knock controlled fuel enrichment signal to fuel system control unit 4721 Receives power directly from battery 1 Receives power from battery 1 across ignition switch 2 terminal 15 Receives signal from throttle switch 198 when throttle is closed Receives engine load signal from air mass meter 284 via fuel system control unit 472 10 11 12 13 16 17 20 23 Receives engine speed and crankshaft position signal from speed position pick up 41 3 Grounds screen of lead from speed position pick up 413 Grounds screen of lead from knock sensor 218 Receives signals from knock sensor 218 Transmits ignition pulses to power stage 419 Transmits speed information to fuel system control unit 472 Grounds control unit 260 Receives engine speed and crankshaft position signals from speed position pick up 413 Power st
15. F 89 EZ 116K B204 E 89 N B Due to differences in model specifications from country to country the number of control unit variants used for the various ignition systems and engines may exceed that listed above Group 28 Ignition systems Design and function General General Function of ignition system combustion theory in brief Correct ignition timing A The function of the ignition system is to ignite the compressed fuel air mixture in each cylinder at exactly the cor rect instant Ignition is followed by the propagation of a flame front through the combustion chamber until the com plete charge has been burned The combustion pressure which is higher than that of the compressed mixture gen erates a high force which drives the piston downwards in the cylinder Although a proportion of the energy released is converted into mechanical work by the crankshaft most of the energy in the fuel approx 70 is dissipated in the form of cooting losses exhaust gas losses and mechanical losses To ensure that the ignition timing is as close as possible to the correct setting under all running conditions the tim ing must be adjusted continuously to take account of variations in the conditions In other words the optimum tim ing is nota fixed setting for each engine but varies with factors such as engine speed load fuel air ratio and temper ature Furthermore the timing may be adjusted for optimum comfort maximum torQue or maxim
16. Hg Positive 7 5 1 105 140 2 03 2 70 in Hg 175 215 3 38 4 15 in Hg 250 4 83 in Hg Negative 2 541 105 180 2 03 3 47 in Hg 135 210 2 61 4 05 in Hg 225 4 34 in Hg Positive 7 541 60 210 3 09 4 05 in Hg 200 240 3 86 4 63 in Hg 300 5 79 in Hg Positive 10 1 105 135 2 03 2 61 in Hg 115 145 2 22 2 80 in Hg 210 4 05 in Hg 75 Group 28 Ignition systems Specifications Timing curves B230A Direction of advance Total advance Advance commences at vacuum mm Hg Settings 5 at vacuum mm Hg 2 at vacuum mm Hg Max advance at vacuum mm Hg Direction of advance Total advance distributor degrees Advance commences at vacuum mm Hg Senings 1 at vacuum mm Hg 20 39 1 40 sp 60 OD 1000 1500 200 LB a 3000 3500 40Q0 rwn EIUS d A seestteeerills 2 ud f 4 M 76 Max advance at vacuum mm Hg Positive 7 541 105 145 2 03 2 80 is in Hg 165 210 3 18 4 05 in Hg g 240 4 63 in Hg i mn e e HITTT PHE HH I uid mus gt HI LIII e 0 40 e e s mE 30 40 hpa 300 200 7 100 200 300 mmHg 138 222 m c2 ts st 1000 i sos 2000 po 3000 3500 4000 r min COME Lm Hn E Ignition leads B19E B19ET B23E B23ET B23FT 828A B2SE B28F B200K B200E B200ET 8204 B230A 275 690 6 1984 270 479 9 11984 275690 6 1984 270479 9 1984
17. V NIB Measure voltage at diagnostic unit connector if voltage is not present at control unit or if instrument reads 12 V with pushbutton depressed NII At diagnostic unit Me sure voltage between connector blue lead and ground Voltmeter should read approx 12 V Measure resistance between connector black lead and ground Ohmmeter should read 0 ohm Switch off ignition NIB Measure resistance between diagnostic unit test lead and pin No 8 under function selector Ohmmeter should read infinity oc Press function selector button Ohmmeter should now read 0 V 219 Group 28 Ignition systems Fault tracing Rex l Connect diode tester between diagnostic unit LED and test lead Connect red probe on diode tester to pin under LED and black probe to test lead LED is operating correctly if diode tester gives indica tion Replace diagnoslic unit if no indication is observed N19 Check for voltage at control unit Switch on ignition Measure voltage between control unit connector termi nal 6 blue and ground Voltage should be approx 12 V Switch off ignition N20 Check control unit ground lead Measure resistance between connector terminal 20 brown and ground Resistance should be 0 ohm N21 Check temperature sensor Measure resistance between connector terminal 2lredl black and ground 813 Ohmmeter reading should agree with adjoining chart If value is incorrect Measu
18. and fuel systems has been one of the most significant factors in this development Compared with their mechanical counterparts electronic or microprocessor controlled ignition systems offer ad vantages such as greater reliability optimum timing under all driving conditions and few moving parts reducing service requirements to a minimum As a result Volvo has in recent years completely replaced its relatively simple mechanically controlled contact breaker systems with sophisticated systems controlled by microprocessors and electronics Equipping system control units with various additional program functions and integrating them with other control systems and components has enabled traditional ignition systems 10 be augmented by features such as temper ature eompensated timing for faster engine warm up improved exhaust gas composition and lower working tem perature Other functions which may be controlled by an electronic ignition system control unit include fuel cut off under engine braking deceleration conditions and ignition retardation in individual cylinders to eliminate knock Volvo markets a wide range of models with a series of engine options This combined with rapid developments in the field of electronics means that a wide variety of electronic ignition systems of different types and degrees of re finement now exist Systems of this type impose completely new demands on fault tracing procedures A certain basic understandi
19. by interruption of the primary current is fed to the distributor 28 for delivery to the appropriate spark plug 29 The control unit computes the timing on the basis of the following information Engine speed and crankshaft position signals are supplied by the speed position pick up 2 Engine knock is detected by the knock sensors 7 Ignition in NO 1 cylinder is indicated by the No 1 cylinder detector 15 Engine load signals are supplied by the fuel injection system control unit 19 Engine temperature is indicated by the temperature sensor 23 Closure of the throttle is indicated by the throttle switch 24 The ignition pulse is interrupted by the control unit at a speed of approx 6300 r min The control unit can vary the timing from approx 60 before TDC to approx after TDC 55 Group 28 Ignition systems Design and function System descriptions EZ 115K 147 116 EZ 115K No 1 cylinder detector Since the B280 engine is equipped with twin knock sensors one for each bank of cylinders the control unit must be able to distinguish between the two in order to determine which cylinder is knocking For this purpose the high tension lead to No 1 cylinder is fined with an inductive detector 15 The device consists of a coil 16 wound on a core 17 surrounding the ignition lead 18 The current pulse induced in the coil by the HT current in the lead as the cylinder fires is the signal used by t
20. descriptions Functional test program The system monitors the operation of certain components and swilches by operation of the items in question When the component or switch is operated in accordance with a set procedure the LED displays a 3 digit code in confirma tion Failure to display a code indicates that the control unit has failed to detect operation of the component switch In this event the fault may tie either in the item itself or in the associated wiring and connections The functional test program provides an ideal means of checking that the switches are correctly wired e g on com pletion of repair work on Ihe engine As an example it may be used to check whether the speed position pick up andJ or wiring is intact if the engine fails 10 slart Some major differences The EZ 116K1Rex 1 diagnostic system differs from other EZ K systems in the following respects when used to per form the same type of faull tracing 64 The use of a test diode is unnecessary This has been superseded by the diagnostic unit which in effect is an ex tension of Ihe ignition system The engine must be switched off during fautt tracing Since the diagnostic system can display a greater number of faull codes it covers a wider range of potential faults enabling them 10 be identified more quickly The system includes a fault free code All fault codes are of Ihe 3 digit type The lechnician decides when the nexi faull code is to
21. following procedure provides a systematic check and inspection of the complete ignition system If the engine can be started commence fault tracing with the test diode to establish the source of the fault Otherwise proceed to page 136 Fault tracing with tast diode Connect test diode special tool 5280 to test terminal on left hand wheel housing yellow red leadl Connect red lead to battery positive terminal Switch on ignition Diode should light Start engine in crease speed to above 3000 r min and reduce to ap prox 1000 r min This will initiate internal diagnostics One flash Max timing retardation 9 B Two flashes Low battery voltage Three flashes Fault in control unit knock sensor circuit Replace control unit Four nashes Fault in knock sensor or wiring See H19 page 1461 Five flashes Faulty load signal from fuel system con trol unit 135 Group 28 Ignition systems Fault tracing EZ 1 02K 136 Symptom Engine does not start Fault tracing First check whether or not the fault is in the ignition system by checking for a spark at one of the plugs Disconnect a plug lead connect it to a spare plug and operate the starter motor N B Ensure sparking does not take place in vicinity of other wiring Spark present Ves Engine or fuel system fault No Check for spark at ignition coil Connect an ignition lead and plug directly to the coil Ground the plug and operate the starter mot
22. for computation oftim ing Connection for screen of lead from speed position pick up 413 12 13 14 15 Grounds screen of lead from knock sensor 218 Receives signal from knock sensor 218 for retardation of timing in cylinder affected by knock Spare Spare Group 28 Ignition systems Design and function System descriptions N 23 j 10 e n 17 J J B r 12 16 5 42 L EMNEN 7 ab ABC REX 1 Banery t98 Throttle switch 2 Ignition switch 218 Knock sensor 5 Distributor 260 Rex l control unit 6 Spark plug 413 Speed position pick up 12 7 Check engine warning lamp 420 Power stagelignition coil 84 Coolanttemperalure sensor 473 Regina control unit 86 Speedometer 482 Diagnostic unit 16 Transmits ignition pulses to power stage ignition coil 420 Power stage interrupts supply to coil when signal 17 18 19 20 21 22 23 24 25 Po a b OU 62 goes low 0 V Transmits engine speed signals to Regina control unit 473 terminal 1 Spare Spare Grounds control unit 260 Spare Spare Receives engine speed and crankshaft position signals from speedlposition pick up 4131for computation of tim ing Spare Spare wer stagelignition coil connections Grounds power stageJignition coil 4201 signal ground Receives ignition pulses from control unit 260 lerminal16 Control unit permits charging of coil through power stage white signal remains hi
23. high performance under fluctuating conditions Neither may these requirements be permitted to vary even following an extended period of driving Timing curve symbols Both figures illustrate the manner in which the timing angle al varies with the engine speed n and the vacuum pi in the intake manifold The angle a increases with speed in other words ignition ofthe fuel air mixture takes place earlier as the speed rises The angle also increases with the vacuum in the intake manifold i e as the engine load falls and the fuel air charge supplied to the engine becomes smaller Contact breaker ignition systems A Contact breaker ignition systems control the timing with the aid of a centrifugal governor 1 and a vacuum ad vance unit 2 Being a speed dependent device the governor advances the ignition as the speed increases while the vacuum advance unit retards it as the engine load increases in response to the vacuum signal from the intake manifold The two devices operate independently within a tolerance band of approx 2 4 Overall this means that the system controls the timing within a tolerance range of approx 4 8 since the setting is the sum of the angles in dicated by the two curves Furthermore the variation which results from wear of the breaker points affects the over all timing Electronic ignition systems B The control unit 3 of an electronic ignition system by contrast is programmed with a series of spec
24. in the cap is altered by this procedure The TZ 28H system employs a distributor with a vacuum advance unit to supply engine load information Group 28 Ignition systems Design and function Speed and crankshaft position information Speed and crankshaft position information Hall generator Function and location The Hall generator 1 supplies the control unit with information on engine speed and crankshaft position The de vice is mounted inside the distributor cap Construction The generator is based on the principle of the Halt effect whereby the flow of current in a semiconductor is deflected if the component is exposed to a magnetic field This causes a potential difference i e an excess of electrons on one side of the semiconductor and a deficiency on the other producing a voltage known as the Hall voltage Following amplification this voltage is employed by the control unit as a signal to control the timing The Hall generator 1 is a U shaped element with an opening for the trigger rotor 2 The number of rotor vanes is the same as the number of cylinders in the engine The generator consists of a Hall le element 3 comprising a Hall effect detector and a transistor amplifier A magnet 4 with a three pole connector 5 is located on the opposite side of the rotor to the Hall IC element The connector terminals are connected respectively to a 12 V supply a 5 V reference signal from the control unit 01 and g
25. information by an air mass meter located in the intake system A measure of the quantity of air supplied to the engine the air mass meter signal is transmitted to the LH Jetronic control unit in which it is converted and used to determine the quantity of fuel to be injected and then to the ignition system control unit Differences Within the EZ K group the individual systems are distinguished by the timing curves used for different engine var iants by whether a Hall generator or inductive speed position pick up is used and by when the ignition compensa tion functions are activated Group 28 Ignition systems Design and function Overview Review of electronic ignition systems Il EZ l02K was introduced in 1984 in conjunction with the launch of the 760 Turbo with the 823 FT engine and IH 2 1 fuel injection system on the American market EZ 102K is equipped with a thermostat which transmits a signal to one of the control unit terminals when the engine temperature becomes excessive commanding it to advance the timing if the throWe is closed The first EZ K system to be used by Volvo EZ 102K remained in production only for a year before being superseded by more up to date variants according as the new family of engines was introduced EZ 117K is very similarto EZ 102K in configuration although designed for the 8230 F and 8230 FT engines with the IH Jetronic 2 2 fuel injection system The system was introduced with the new family of engine
26. is a feature of EZ 117K on the B230FT engine and of all variants of EZ 11SK and EZ4 16K The function is activated only within a certain speed and load range in addition to which acertain average knock controlled retar dation must already have been applied in all cylinders The following conditions are required for the intervention of the knock controlled fuel enrichment function on the various ignition systems engines EZ M7K on B230FT 6 retardation in all cylinders in response to knock detector signals EZ 115K on B280E F Retardation of at least 10 in all cylinders in response to knock detector signals at engine speeds above 3800 r min and above a certain minimum load EZ 116K on 8 234 F Retardation of at least 3 40in all cylinders in response to knock detector signals at engine speeds above 3800 r min and above a certain minimum load 39 Group 28 Ignition systems Design and function Compensation functions 147 102 Throttle switchlidling air control switch Function and location The throttle switch 1 supplies a signal to the ignition system control unit when the throttle is fully closed The signal is used to enable the control unit 4 to select a timing setting which is suitable for idling and engine braking condi tions The throttle switch detects the throttle position 2 by measuring the rotation of the spindle 3 Signal Throttle closure for example under idling and engine braking conditions gr
27. is more accurate than that supplied by a vacuum line from the intake manifold In addition the air mass meter responds more quickly and is not subject to measurement errors caused by variations in air den sity In other words it is independent of air temperature and height above sea leveL Should the fuel system control unit fail for any reason to supply the ignition system control unit with a load signal the latter will compute the timing on the basis that max load conditions prevail when the throttle has opened 26 Group 28 Ignition systems Design and function Regina fuel injection REGINA REX I Regina fuel injection system General The injection system control unit 1 supplies the ignition system control unit 2 with information on engine load acting in other words as a sensor for the latter The gas pressure in the cylinders during the compression stroke will rise as a greater charge of fuel air mixture is supplied to the engine and the ignition system will retard the timing according as engine load increases Signals The electronic pressure sensor 3 and air temperature sensor 4 supply voltage signals to the Regina control unit 1 Taken together these signals provide a measure of engine load and are processed by the Regina control unit to compute the quantity of fuel to be injected Once the load signals have been converted into digital form i e into square wave pulses they are transmitted to the
28. reference point The angular pitch between two adjacent short teeth y is 6 0 3607 60 The con trol unit identifies TDC as the point 90 after the passage of the long tooth The type 6011 toothed profile is used on the EZ 116K system This means that the control unit applies a factor of 16 to improve the resolution of the pick up signal In effect the control unit can adjust the timing in steps of 0 375 The EZ 15K ignition system for B280 engines is designed for a flywheel with a type 6013 toothed profile The pro file is provided with 60 drilled holes and 3 long teeth each of which is twice the length of a short tooth In other words the profile is provided with 54 60 3x2 short leeth and 3 long teeth as the crankshaft position reference points The angular pitch between two adjacent short teeth ZO is 6 0 360 760 The three long teeth are located 120 apart langle cl The control unit identifies TOC as the point 60 after the passage of a reference tooth The control unit applies a factor of 16to improve the resolution of the pick up signal In other words the unit can adjust the timing in steps of 0 375 Group 28 Ignition systems Design and function Engine oad information 147 092 Engine load information Intake manifold vacuum The control unit is supplied with information on engine load through the vacuum line 1 from the intake manifold load information through vacuum line When the engine load is lo
29. sufficient amount without any significant risk of further knock EZ K systems 8re equipped with 8 similar knock control function 36 Group 28 Ignition systems Design and function Compensation functions Adaptive timing retardation Background function If normal engine load is exceeded for longer than usual for example when the car is driven up along incline is pull ing atrailer or is running on low grade fuel knock controlled retardation will intervene more often The adaptive re tardation function on the other hand retards the timing by a small amount for a longer period to reduce the risk of knock at specific combinations of engine speed and load Meaning roughly self learning the term adaptive is used to describe the fact that the control unit after a time tearns that running conditions have changed more or less permanently The function is applied individually to each cylinder Conditions On the upper curve green the upper position on the vertical axis represents a combination of engine speed and load which experience has shown to be particularly susceptible to knock The horizontal axis is the time scale cali brated in this case in tens of minutes If the control unit detects that the load speed increase is of a permanent nature Le that it has lasted for a specific time it will adopt the adaptive retardation mode when knock occurs Activation The lower curve illustrates the practical effect
30. to flash rapidly If not proceed to N11 N18 N7 Operate throttle control in engine compartment lamp should first go out and then display code 334 in dicating that throttle switch is operating correctly in idling position See N22 if code is not displayed but lamp continues to flash rapidly N6 Operate starter motor I amp should first go out and then display code 141 in dicating that pulse generator signal is okay See N24 if code is not displayed but lamp continues to flash rapidly Switch off ignition Group 28 Ignition systems 146 715 Fault tracing Hex Engine does not start NB Check control unit and power stage ground connections Ground leads brown and black should be tightened securely to terminals on intake manifold N9 Check for spark at spark plugs Caution Fuel system control unit may be destroyed if spark strikes injector or unit wiring Disconnect HT lead from one spark plug and connect to spare plug Ground plug and operate starter motor If powerful blue white spark is present Fault is located in engine or fuel system NIO tf spark is weak or absent Connect plug and HT lead directly to ignition coil HT terminal Ground plug and operate starter motor If spark is still weak or absent fault is located in igni tion coil or ignition system LT circuit see N11 N36 If powerful blue white spark is now present check rotor distributor cap and HT leads Replace as
31. 0 4110 Grounds screen of lead from No 1 cylinder detector 416 7 26 Receives signals from speed position pick up 413 7 25 Grounds screen of lead from knock sensor Il RH 2 18 7 24 Receives signal from knock sensor II RH 218 7 24 Power stage connections c RGOmN Controls current in ignition coil 4 21 1 primary winding Grounds power stage 419 4115 Grounds screen of lead from control unit 2601 41101 terminal 16 Receives supply from battery 1 1 1 across ignition switch 21 3 1 Receives ignition pulses from control unit 260 4110 57 Group 28 Ignition systems Design and function System descriptions 147 III EZ 116K B234F B204E and B230F The control unit 1 computes the optimum timing on the basis of information from the various sensors The power stage 2 makes and breaks the current in the primary winding of the ignition coil 3 in response to ignition pulses from the control unit The high tension current thereby induced in the secondary is supplied to the appropriate spark plug 5 by the distributor 4 The control unit also supplies signals to the diagnostic unit 7 used for fault tracing and monitoring purposes The ignition setting computed by the control unit is based on the following information Engine speed and crankshaft position are indicated by the speed position pick up 6 Engine knock is detected by the knock sensor 8 The fuel injection system 1H 2
32. 0 FIFT EZ cif 07 99 2z2z E f A N oecte2z2g29znmunaxau gay C gt Wan 7 ad lt S 2 Ng 7T ANY NN NY KOY WY o v Y GR l B EZ 117K Ignition system 8230 FIFT 1 Battery 202 Climate control A Connector RH A post 2 Ignition switch 217 Fuel system control unit 8 Connector LH A post 4 Ignition coil 218 Knock sensor C Connector 81 LH wheel houling 5 Distributor 224 Radiator fan thermostat o Ground terminal on intake m nifold 6 Spark plugs 260 Control unit E Connector t RH wheel housing 11 Fusebox 267 Test connector F Connector at LH wheel housing 29 Positive terminal board 293 Idling compensation relay 81 AC pressure switch 419 Power stage 86 Rev counter 156 Radiator fan motor 198 Throttle switch 200 AC compressor solenoid A miyor 2 y 2 pm R SB M R SB x ups C EZ 118K Ignition system 8230 K 8200 230 E ed SSA v 4 Eum KS a oar r Das PO LN fa d P Se Ets SENS 218 7 7 RW B 230K y 4l 3 2 BN l OR BI S8 BN ON EZ 118K Ignition system B230K B200 230 E 1 Battery 224 Radiator fan thermostat 2 Ignition switch 260 Control unit 4 Ignition coil 267 Test connector 5 Distributor 271 fuel cut off solenoid 6 Spark plugs 272 Microswitch 11 Fusebox 273 Temperature sensor 29 Positive terminal board 293 Idling compensation relay 81 AC pressure switch 419 Po
33. Rex I control unit 2 The digital signal consists of current pulses 5 of a duration 6 proportional to the engine load Should the load signal from the Regina control unit be lost for any reason the ignition system control unit will compute the tim ing on the basis of max load conditions provided that the idling switch is not closed 27 Group 28 Ignirion sysrems Design and function Compensation functions Compensation functions Theory of knock Knock is caused by detonation of the fuel air mixture in the combustion chamber What is knock Detonation may occur either aher las in Alar before as in 51 the plug has delivered a spark In either case the mixe ture is ignited at two or more points in the chamber and combustion progresses from these points le This results in the simultaneous propagation of two or more flame fronts causing abnormally rapid and uncontrolled combustion accompanied by an explosive rise in pressure which produces the typical metallic sound known as pinking or knock Compression knock A In the case in which knock occurs aher the plug has delivered a spark detonation is caused by the fact that the flame front initiated by the spark compresses and heats the unignited mixture to the point at which detonation is unavoidable A relatively high engine load is required to produce this type of knock Glow ignition knock B In the type of knock which occurs before the plug has
34. Z 117K Control unit 1 336 505 1 1 346 469 8 Power stage 1 332 584 0 1 332 584 0 Knock sensor 1 367 644 0 1 367 644 0 Throttle switch 1 306 938 0 1 306 938 0 EZ 118K Control unit 1 336 800 6 1 336 503 6 1 336 506 9 135196 3 Power stage 1 332 584 0 1 332 584 0 1 332 584 0 1 332 584 0 Knock sensor 1 367 644 0 1 367 644 0 1367 644 0 1 367 644 0 Temperature sensa 1 332 396 0 1 332 396 9 Microswitch 1 357 943 8 1 357 943 8 1367 734 9 1 367 734 9 EZ 116K 8230F 8204E 8234F Control unit 3 501 688 0 Calif 1 367 178 9 3517608 8 3 517 402 8 USAIEU USA Fed Power stage 3501 921 5 3501 921 5 3 501 921 5 Knock sensors 1 367 644 0 1 367 644 0 1 367 644 0 Temperature sensa 1 346 030 8 1 346 030 8 1 346 030 8 Throttle switch 3517 068 7 3517 068 7 3517 068 7 Speed position pick up 389 399 7 13893997 1 389 399 7 Diagnostic unit 1 398 703 7 1 398 703 7 1 398 703 7 Rex I Control unit 1 389 567 7 Power stage 1367 438 7 Knock sensor 1367 644 0 Temperature sensor 1 346030 B Speed position pick up 1389399 7 Throttle switch 1 389 558 6 Diagnostic unit 1398703 7 78 Group 28 Ignition systems Breakerless ignition systems Contents Procedure Ignition coil and ignition leads A1 A3 Distributor general 81 811 Distributor cap and rotor arm Sessa fis 83 84 Tirming advarce tte Seis nel men M cp IPTE Zine sate 85 811 Static ti mingsz sss EE eke kc 9 9 9 uuuu 9 85 Centrif
35. age connections oso Controls primary current in ignition coil 4 Grounds power stage 41 9 Grounds screen of lead from control unit 260 terminal 16 Receives power from battery 1 across ignition switch 2 Receives ignition pulses from control unit 260 59 Group 28 Ignition systems Design and function System descriptions Control unit connections 1s 2 oo 11 Moos Transmits signals to diagnostic unit 482 when fault tracing Signals are transmined by diagnostic unit when ap propriate diagnostic functions are selected Receives engine temperature signal from temperature sensor 84 for timing compensation if required Control unit supplies one of NTC resistors in sensor with constant voltage and measures resulting voltage level in ternally Grounds connection when certain types of fault are present in system Grounding closes circuit to combined in strument illuminating Check engine warning lamp 1217 Spare Receives supply from battery 1 for self diagnostic program memory Receives supply from battery 1 across ignition switch 2 terminal 15 Receives signal from throttle switch 198 when throttle is fully closed Control unit respond by selecting timing curve which is speed dependent only Receives engine load signal from Regina control unit 473 for computation of timing Receives engine speed and crankshaft position signals from speed position pick up 413
36. aks the current in the primary winding of the ignition coil 6 at the correct instant generating a high tension current in the secondary The HT pulse is fed to the distributor 7 for delivery to the appropriate spark plug 81 Apart from the rotor the distributor contains no mechanical or electronic components its sole function being to dis tribute the high tension current to the correct plug At idling speeds of less than 1000 r min the control unit advances the timing by 5 to prevent a drop in speed when the AC system is switched on or when a drive position is selected on an automatic model 45 Group 28 Ignition systems Design and function System descriptions 147 106 Control unit connections 1 Supplies speed signals to rev counter 86 2 Connects control unit 406 to ground 3 Receives supply from battery 1 via ignition switch 21 4 Receives engine speed and crankshaft position signals from speed position pick up 407 5 Receives engine speed and crankshaft position signals from speed position pick up 407 6 Receives signal from idling advance relay 293 on cars with automatic transmission and or AC 7 Spare 8 Spare 9 Connected to radio interference suppression capacitor D 46 Group 28 Ignition systems Design and function System descriptions EZ 102K EZ 102K 823FT 760 1984 with 823FT The sensors supply the control unit 1 with a serie
37. ance at distributor speed r s 0 eee ee se tuus r mmin eo diit igi B28 F Total advance distributor degrees 22 ioe Advance commences at distributor speed ris Soli r minl Settings 5 at distributor speed rns RE ew PLI i CUMIN ae Ox Sid Po sca ee Sect E Stale 10 at distributor speed r s KAT nun a A Lr E Max advance at distributor speed rls M MIN 2 2 sii B230A Total advance distributor degrees ficiis Advance commences at distributor speed r s Scu r m in 74 12 535 1 25 6 7 9 2 400 500 20 26 1200 1560 33 3 39 2000 2340 26 7 16001 12 5x1 5 6 7 11 7 400 700 12 S 16 770 960 17 5 22 3 1050 13401 40 24001 13x1 7 5 9 6 450 575 12 15 15 4 750 9251 23 3 32 5 1400 1950 40 2400 ESI 8 5 10 500 600 12 4 15 3 740 920 30 50 1800 3000 33 3 2000 12 5x1 5 7 5 10 5 450 630 Group 28 Ignition systems Settings 50 at distributor speed ris r min 10 at distributor speed rls r m n Max advance at distributor speed rAs rlmin sess E Vacuum advance unit B19E B23E Direction of advance Total advance Advance commences at vacuum mm Hg Settings 50 at vacuum mm Hg 2 at vacuum mm Hg Max advance at vacuum mm Hg Direction of advance T
38. arding the ignition increases the exhaust gas and coolant temper atures The lower cylinder temperature is due to the reduced pressure of the mixture when it is ignited while the rise in exhaust gas temperature is due to scavenging of the gases closer to the exhaust valve opening point The higher coolant temperature is attributable to the fact that less of the energy content of the fuel is converted into mechanical work a higher proportion being dissipated in the form of thermal losses As a result a higher quantity of heat is transferred more quickly to the cylinder wall exhaust gas port intake manifold and coolant passages Timing compensation on cold engine Temperature compensation of the timing on a cold engine usually involves advancing the timing to shorten the warm up period However temperature controlled functions which retard the timing in a cold engine are also used One of the effects ofthis is to bring the catalytic converter up to working temperature more quickly while another is to increase the coolant temperature accelerating the defrosting action of the climate control system The temperature sensor signals may also be used by the control unit to determine when the knock sensor signal should be switched in Blocking this signal when the engine is cold ensures that the control unit is unaffected by spu rious signals caused by the mechanical noise typically emilled by the engine as it warms up Timing compensation on hot engine
39. be displayed The system includes a functional test program providing afasl and reliable means of checking that certain switch es have been reconnected correctly following repair work on the engine Switching off the ignition and Slopping the engine is not sufficienllO erase the memory In this case the memory can be erased on completion of work only by operaling the pushbutton in a predetermined sequence Group 28 Ignition systems Design and function System descriptions 25 05 05 05 o5 0 5 n 05 KLAS MN a EZ 116K OHNE The following preliminary steps must be carried out to ensure that the LED displays the codes The coding cable must be connected to socket 6 The ignition must be switched on without starting the engine i e the key must be turned to switch position Il Pushbutton A must then be pushed once or twice for not longer than 3 seconds One operation activates the self diagnostic function and two operations the functional test program The following fault codes are displayed when the self diagnostic function is selected 1 1 1 No faults 1 4 2 Internal control unit fault engine runs with timing retarded to fail safe setting 1 4 3 Faulty knock sensor engine runs with timing retarded to fail safe setting 1 4 4 No load signal from fuel system control unit 2 1 4 Faulty speed position pick up signal 2 2 4 Faulty temperature sensor signal engine runs as though hotl 2 3 4 Faulty throttle switch si
40. ch enable the control unitto ad just the timing to compensate for unusual running conditions Thus sensors F H may be regarded as providing the ignition system with compensation functions In the event of engine knock the phenomenon whereby the fuel air mixture is ignited by a source other than the spark plug the knock sensor Fl mounted on the engine will transmit a signal to the control unit commanding it to retard the ignition Complete closure ofthe throttle is indicated by a throt tle switchlidling switch G When the engine is idling the control unit regulates the timing in accordance with an idling program to ensure optimum comfort while the timing under engine braking conditions is controlled to mini mize exhaust emissions The signal supplied to the control unit by the temperature sensorhhermostat enables the unit to apply the appropriate timing compensation when the engine temperature is unusually high or low Group 28 Ignition systems Design and function Overview IGNITION SYSTEM ENGINE YEAR TSZ 4 B28A 82 85 TSZ 4 B28 E 82 86 TSZ 4 B28F 82 86 TZ 28H B 19 E 84 TZ 28H B23 E B4 TZ 28H B 230 A 85 86 MOTRON C B 23 ET BA MOTRONIC 8200 ET 85 MOTRONIC B 230 ET 85 RENIX F B 200 K 85 REX I B 230 F 89 EZ 102K B 23 FT 84 USA EZ 117K 8230 F 85 88 EZ 117K B 230 FT 85 EZ 118K B 200 E 85 EZ 118K B 230 E 85 EZ 118K B 230 K 85 86 EZ 18K B 230 K 87 EZ 11 5K B 280 E 87 EZ 115K B 280 F 87 EZ 1 16K B 234 F 88 EZ 116K B 230
41. ch oc cur in the combustion chamber During the combustion process the temperature rises at intervals to a value of perhaps 2500 C andthe pressure to approx 60bar 870 psi Almost immediately during the induction stroke the plug comes in contact with the cold uncompressed fuell air mixture which is likely to be at the same temperature as the outside air To ensure operation within the correct operating temperature range spark plugs are made with different heat rat ings or ranges for different engine types If the operating temperature is too low i e below about 400 C the plug will rapidly become coated with combustion residues This type of fouling weakens the spark and causes the en gine to miss On the other hand if the operating temperature is too high over approx 1000 C the fuellair mixture may be ignited by the incandescent plug surfaces initiating uncontrolled combustion Every engine manufacturer specifies the appropriate heat rating on the basis of parameters such as specific engine output probable running conditions and climatic conditions A plug with a high heat rating has a greater thermal retention capacity and conducts less heat away from the com bustion chamber This type is normally used on low speed engines operating at relatively low combustion tem peratures Plugs of this type are also known as hot plugs and are provided with a long insulator nose as shown in Fig 1 A spark plug with a low heat rat
42. configurationS 16 Power stage and ignition Coil ps aruas ns ssis ec ce te eee eee 17 DISthIDUIOl s 2 c0222 Sees ics fil eemzniecnifcideunueierig xs e crus nus 19 Speed and crankshaft position information Hall geherator 5245 Bele oe als em ded payee gi ced err RAenb obs haan eh eer rea aaa 220 Speed position pick up and flywheel configuration 22 Load information Induction manifold vacum reitse nei lw mor i Pach ewsaten eiii eni AD Fuel injection system control unit orn onec dons ET f chad 26 Compensation functions lheory of knock 0070 bessere ed eu asse ee Sneath ion ARIS 28 KnoCle sens Ol oon ates fe oer dtt ce Sis etudes sea St fyc tese E E 30 Kriock Control au Inm UT eR Utm cux TENE CNET RN ei seine 32 Knock controlled fuel enrichment EA Sgt ee ates Scat ees tens 39 Throttle switchlidling switch 0 0 22022 eee eee eee Cosson os Pies Pla wed 40 Temperature Sensor 22 eee ee eee eee eee MeL old PLU eL LL CET LP 4 System descriptions TSA C PUR haere ce carb apes m 43 TZ 28b ems tenis TEASE e 44 ReniX Fe caos daa a hebr te Rte Se ease SO ue intent a ADEA S Idea 45 EZN02K vac cose ess Shera Ors Bese Det ce rc vem ee eat LE E ED QUE 47 EZ4A 17K LE nai edan ts ao E nave Dance ene e oe yea Soc auc weceees QP EZA TBK seias eart attend ous E T E curd Pesci siue a Dti E T Pee lees 51 rA S edis idus e obse ele ed uS usen ageless marri
43. creases the risk of knock the control unit incorporates a function which re tards the timing sharply for a brief period under these conditions The function of load controlled retardation is to re duce the likelihood of knock when the accelerator is suddenly depressed Background High engine load equivalent to the injection of a large quantity of mixture is a prerequisite to the occurrence of the more common types of knock Thus for example when the accelerator is suddenly depressed the control unit may be unable by virtue of its design to retard the ignition quickly enough by an amount equivalent to the load increase For this reason certain cars may be subject to what is known as transitional knock if driven in too high a gear with the accelerator to the floor Sharp retardation To overcome this problem the control unit incorporates a program controlled function which retards the normal timing by 8 in response to a load signallfrom the fuel control unit indicating a sudden pressure drop in the in take manifold Rapid re advance The control unit then restores the timing very rapidly to the normal value o This is carried out in steps of 1 every five engine revolutions both values approximate regardless of whether the higher load condition is of longer dur ation Should the rapid pressure drop be followed by full opening ofthe throttle the control unit will have sufficient time to again retard the basic timing by a
44. delivered a spark detonation of the mixture may be due to incandescent carbon particles or gasket edges fouled spark plugs or other areas of the combustion chamber which absorb heat more easily IThis phenomenon is sometimes known as glow ignition Effects of knock C The abnormal pressure rise which accompanies knock subjects the piston gudgeon pin connecting rod crank shah and bearings to abnormally high mechanical stresses Furthermore the temperature rise caused by the phe nomenon is so high that the cylinder wall piston and spark plug may easily suffer damage while the energy con tent of the fuel is poorly utilized The unusual engine resonance caused by knock is detected by a knock sensor mounted on the cylinder block The sensor signal is transmitted to the control unit 28 Group 28 Ignirion sysrems Design and function Compensation functions Knock threshold Under certain conditions however the combination of high perlormance and low fuel consumption demands that the engine runs as close as possible to the knock threshold The closer the timing curve to the threshold Ihe higher the efficiency of fuel utilization In other words the knock threshold is not a fixed limit but varies depending on run ning conditions Methods of preventing knock Knock may be prevented by retarding the ignition Since detonation of the mixture occurs when the piston is closer to TOC the pressure and temperature in the cylinder are t
45. device consists of a diaphragm a magnet and a semiconductor element The diaphragm is actuated by the vacuum on one side while the other is attached to the magnet The position of the magnet influences the current flow in the semiconductor and as a result the value of the induced Hall voltage Thus the voltage is proportional to the position of the magnet and by extension to the engine load The load sig nal is received by the converter in the control unit and used to compute the timing 25 Group 28 Ignition systems Design and function Engine load information Fuel injection system control unit LH 2 1 LH 2 2 LH 2 4 The fuel system control unit 1j supplies the ignition system control unit 2 with information on engine load This based on signals from an air mass meter 3 the quantity of induction air being used as a measure of the load Signal The air mass meter continuously measures the quantity of air drawn into the engine and delivers a variable signal to the injection system control unit in which the signal is converted into digital form and used to compute the quantity of fuel to be injected The signal is also relayed to the ignition system control unit The digital signal consists of a series of current pulses 4 of a duration 5 proportional to the load Advantages This type of load information is used in E2 K systems with LH Jetronic fuel injection and Rex l systems with the Regi na injection system and
46. e is relatively long The in terval is equivalent to approx 80 revolutions at an engine speed of about 6000 r min At low engine speed the corresponding interval is about half that at high speed lapprox 35 revolutions at an engine speed of about 1000 rlmin The re advance rates vary across the speed range becoming slower as engine speed increases 34 Group 28 ignition systems Design and function Compensation functions Reason for different re advance rates Faster re advance rates are possible in the lower speed ranges since ignition then takes place when the piston is closer to TDC and the risk of knock is consequently lower Fast re advance is more advantageous since it serves to increase the mean value of the timing angle As already described advancing the timing point improves the effi ciency of fuel utilization Slower re advance rates are chosen at higher speeds since ignition then takes place relatively early as the piston moves upwards towards Toe and the attendant risk of knock is greater Increasing the rate of re advance under these conditions would greatly increase the likelihood of recurring knock EZ K systems employ more or less the same method of varying the re advance rates following knock controlled retardation 35 Group 28 Ignition systems Design and function Compensation functions o p 147 098 Load controlled retardation Function Since a sudden increase in load greatly in
47. ed elisenibida 55 EZI dG Kata scree uet Ease D E m oases 58 REX ee are N O E Rd 60 Diagnostic system EZ 116K and Rex l 63 Contents Group 28 Ignition systems Contents Test equipment leen tieu bee ILLIUS toate ow cor o Sleds Mele weemes 68 Instructors deri teen dt aoa a we ee ed ea daea tede ete siasdveny 09 Specifications DLE LL c E EL M 71 78 Breakerless ignition systems E T P e dore ANERER 79 Fault tracing nassen sire monad uus PT aa e e at an r aoa Rie a A ea eae sel OD Aenbx E 22 cs m eea Osaa ura o Se Eee Se Age coe eke ee Aes in E EZ 117 118K Mu n eer POE eee ee Rect Aes PIENE eI E eL 169 EZ 116K 187 BAexasseicSe zau weg Seine bo Red aes eater ges tes OSs ws egasecenpegue ciel See Service Manual Fault tracing repair and maintenance Section 2 23 B23 B 200 B 230 ET Engines 740 760 Turbo for details of Motronic systems Order No TP 30949 1 Index page 227 Order No TP 31397 1 Supersedes TPI31059 1 USA We reserve the right to make changes without prior notification 9 VOLVO NORTH AMERICA CORPORATION Group 28 Ignition systems Introduction Introduction Comprehensive development work by Volvo has resulted in the design of engines boasting high performance low fuel consumption cleaner exhaust gases a high standard of reliability and simplified service procedures The ever increasing use of microelectronics for the control and regulation of ignition
48. en the various tem perature dependent timing adjustments must be made Before considering the beneficial effects of temperature compensation on the timing some effort should be made to gain an understanding of the effects of variations in timing on the cylinder exhaust gas and coolant temperatures 41 Group 28 Ignition systems Design and function Compensation functions Theory of temperature compensated timing advance Advancing the ignition timing increases the cylinder temperature while reducing the exhaust gas temperature Un der certain conditions this also yields a reduction in coolant temperature The higher cylinder temperature is due to the higher pressure of the fuel air mixture as it is ignited while the lower exhaust gas temperature is due to the rela tively late scavenging of the gases at the end of the combustion process The lower coolant temperature achieved by advancing the timing when idling is partly due to the fact that the setting is already well retarded and that a relatively high proportion of the fuel does not as a result produce mechanical work the energy being dissipated in the form of heat losses Advancing the timing under these conditions greatly improves the efficiency of combustion increasing the amount of energy converted into mechanical work and reduc ing the amount of heat discharged to the coolant Theory of temperature compensated timing retardation Although it reduces the cylinder temperature ret
49. es the adaptive mode at the end of interval a after a predetermined interval approx 10 mini regardless of load If the load remains high a new adaptive period will commence if knock recurs and the cycle will be repeated from the start of interval a Advantages On average this mode of knock control permits a more advanced timing setting to be used an advantage in terms of combustion fuel economy and so on due to the fact that fewer knock controlled retardation operations are re quired when the function is activated Stated in simple terms knock is prevented by detecting the increased risk of the phenomenon 38 Group 28 Ignition systems Design and function Compensation functions 147 101 Knock controlled fuel enrichment Knock controlled fuel enrichment means that the injector opening period is extended to enrich the fuel air mixture reducing the combustion temperature and bringing the uncontrolled combustion under control The function is acti vated if the ignition system control unit detects that knock is occurring in all cylinders above a certain threshold value On receiving a signal from the knock sensor 2 and having established that knock is present in all cylinders the con trol unit 1 connects a terminal on the fuel injection system control unit 3 to ground causing the latter to transmit a signal to the injectors 4 to extend the opening period Knock controlled fuel enrichment
50. following terms be clearly understood in order to avoid confusion a Advancing the ignition timing means that the ignition pulse is delivered when the piston is at a point funher from TOC b Retarding the ignition means that the ignition pulse is delivered when the piston is at a point closer to TOC Under normal conditions the aim is to develop peak pressure in the cylinder about 10 after TOC Under idling conditions the timing is advanced to approx 10 15 before TOC to ensure smooth running The foregoing discussion of how the emissions are affected by the ignition timing is somewhat simplified since there are natural ly many other factors which influence the composition of the exhaust gases 10 Group 28 Ignition systems Design and function General 147 080 Ignition systems basic parameters The ignition system control unit must be supplied with certain basic information in order to compute the frequency or rate at which HT ignition pulses must be delivered to the spark plugs when in relation to the position of the par ticular piston before TOG each pulse must be generated and to which plug the pulse is to be delivered The signals required for this purpose are derived from the engine speed A engine load B and crankshaft position G Speed information A The engine speed provides information on the number of ignition pulses which must be generated per unit of time The number of high tension HT pulses de
51. gh 5 V Power stage opens terminal B ground connection when signal goes low 0 VI Resultant high tension generated in ignition coil is distributed by distributor 5 to appropriate spark plug 6 Receives supply from battery 1 across ignition switch 2 Grounded supply ground Transmits signals corresponding to number of ignition pulses to speedometer 86 in combined instrument Group 28 Ignition systems Design and function System descriptions EZ 116K EZ 116K end Rex Oiegnostic system The EZ 116K1Rex 1control unit 1 incorporates adiagnostic circuit which greatly facilitates fault tracing and monitor ing of the system The system features two separate test functions a self diagnostic function whereby the diag nostic circuit continuously monitors the operation of the ignition system and a functional test program which en ables the operation of certain switches to be tested A diagnostic unit 2l mounted beside the left hand suspension strut housing in the engine compartment is used to communicate with the diagnostic circuit in the control unit Oi8gnostic unit The diagnostic unit is provided with acoding cable 3 which is used to select the system ignition or fuel injection to be tested by inserting the plug in the appropriate socket under the cover 4 The sockets are numbered from 1 to 7 the ignition system being tested using socket No 6 The pushbutton A on top of the unit is used to select the de sired
52. gh power and dangerous voltage levels in both the low and high tension circuits Dangerous voltages are present at all points of the system including connectors etc Switch off the ignition when connecting and disconnecting test instru ments when disconnecting and reconnecting the control unit connector when disconnecting and reconnecting the ignition coil and spark plug leads Battery Do not disconnect the leads when the engine is run ning Disconnect the leads when using a boost charger Do not use a boost charger or a voltage source higher than 16 V when jump starting Control unit Remove the control unit e g when carrying out a stoving operation The unit must not be heated above 80 C Disconnect the control unit connectOr when carrying out electric arc welding Remove the control unit when carrying out electric arc welding in its vicinity Do not replace the control unit without checking all wiring and components otherwise the replacement unit may suffer the same damage Battery It is essential that the battery voltage be normal i e not too lowl when testing the various components A battery charger may be connected as required during testing Max permissible charging current voltage 12 A and 16 V NOTE Do not use a boost charger Group 28 Ignition systems Group 28 Ignition system Firing order B28 B280 Other engines Breakerless 1 6 3 5 2 4 1 3 4 2
53. gnal engine runs with timing retarded to fail safe setting Once a fault code has been displayed the pushbutton must be operated again to display the next code In this case a repeat of the previous code indicates that only one fault is stored in the memory The memory function must be erased when any faults present have been corrected Since the memory accommodates a maximum of three faults further faults if any cannot be displayed until the first three have been corrected and the memory erased This is car ried out as follows Switch on the ignition without starting the engine i e turn key to position Il Depress pushbutton A for at least 5 seconds Wait for the LED to light approx 4 5 secondsl Operate pushbutton A once more for at least 5 seconds Start and run the engine up to normal working temperature Stop the engine switch on the ignition and operate pushbutton A to check that no further faults are present in the memory The LED should display the code 1 1 1 The functional test program is selected by operating pushbutton A twice after the preliminary steps have been car ried out The LED will flash continuously at a frequency of approx 6 flashes per second indicating that the control unit is in the functional test mode The following acknowledgement codes may then be displayed 3 3 4 Throttle switch 1 4 1 Speed position pick up The acknowledgement code indicating that the throttle switch and its wiring connect
54. gnition coil Reassemble control unit connec tor and reconnect to unit Reconnect ignition coillpower stage connectors Check that no new fault codes are displayed I Ignition system 8230F Rex Rex l Ignition system 8230 F 1 Battery 2 Ignition switch 5 Distributor 6 Spark plugs 11 Fusebox 12 Combined instrument CEL 29 Positive terminal board 84 Temperature sensor 86 Rev counter 198 Throttle switch 218 Knock sensor 260 Control unit 413 Pulse generator 420 Power stage ignition coil 473 Fuel system control unit 482 Diagnostic unit OU onmo Connector RH A post Connector LH A post Connector 8t LH wheel housing single pole Ground terminal on intake manifold Connector at bulkhead Connector at LH wheel housing Connector at RH wheel housing 420 BL 3 e BN W sv w mr Bn w 473122 i A 12 7 Index Index Adaptive timing retardation NS ed ses i S Hall generator 20 21 98 102 128 130 141 144 Ballast resistor Ignition coil 69 72 77 78 81 AJEJF 6 cylinder engines 81 107 Ignition coil power stage 17 18 Basic parameters 11 13 Ignition timing table 71 84 Centrifugal advance 74 75 97 109 Knock control 0 2 02 eee eee ri iin 28 38 Control unit 14 16 77 78 Knock controlled fuel enrichment 39 Diagnostic system 0 2 0 004 63 67 Knock sensor 30 31 Distributor 19 73 82 83 87 102 Lubrication Distributor tester 96
55. hat the engine is idling B Certain models equipped with air conditioning are provided with a function which advances the timing when the AC compressor is switched in thereby preventing a fall in idling speed while maintaining the capacity of the AC system The timing advance terminal on the control unit 1 is connected to the electromagnetic clutch circuit on the com pressor 23 and receives a 12 V supply when the pressure switch 124 closes to energize the clutch The control unit then advances the timing if the idling switch 19 also indicates that the engine is idling On the B 230 K engine the above compensation functions intervene only if the engine temperature exceeds 75 C on 1985 86 variants or 85 C on 1987 and later variants Idling compensation operated bv the ignition system control unit is not required on engines on which the idling valve is connect ed to the fuel system control unit CIS system or to a special CIS control unit On engines of this type the CIS valve ensures that extra air 85 well as additional luel is supplied to the engine to compensate for the increased load 52 Group 28 Ignition systems Design and function System descriptions EZ 118K EZ 118K Fuel cut off B 230 K variants only The control unit 1 supplies a signal to the solenoid valve 25 under engine braking conditions when the engine speed is high provided that the idling switch 19 simultaneously indicates that the th
56. he control unit to maintain the cor rect firing order at all times The signal is also used to identify an individual cylinder affected by knock enabling the control unit to retard the ignition in the cylinder affected 56 Group 28 Ignition systems Design and function System descriptions x TU 419 4 zu 11i EZ 115K Control unit connections Receives signal from temperature sensor 84 7 16 Transmits fault signals to test terminal 417 17 4 when test diode is connected Transmits knock controlled fuel enrichment signal to fuel system control unit 217 418 2 3 4 6 7 8 10 Receives supply from battery 1 1 1 across ignition switch 2 31 1 Receives idling signal from throttle switch 198 3 49 Receives toad signal from air mass meter 284 7 17 via fuel system control unit 217 418 Receives signals from speed position pick up 413 7 25 dios 22 13 16 17 la 19 20 21 23 24 25 Grounds screen of lead from speed position pick up 4131 7125 Grounds screen of lead from knock sensor IH 218 7 23 Receives signal from knock sensor IH 2181 7123 Transmits ignition pulses to power stage 419 4115 Transmits speed information to fuel system control unit 217 1418 Receives signal from No 1 cylinder detector 416 7126 Receives signal from No 1 cylinder detector 416 7126 Grounds control unit 26
57. he primary circuit of the coil 18 Group 28 Ignition systems Design and function Components 147 087 Distributor Function The function of the distributor is to conduct the high tension pulse from the ignition coil to the appropriate spark plug A distributor fitted with a Hall generator also provides information on engine speed with the aid of the trigger rotor driven by the distributor shaft Construction and variants The distributor consists of a cap 1 rotor arm 2 shaft 3 and in applicable cases a Hall generator 4 and trigger rotor 5 Older systems employ either contact breaker points or some form of pulse generator A Vertical distributors are driven by an intermediate shaft through bevel gearing B Horizontal distributors are driven directly from the camshaft minimizing the play in the transmission mechan ism This in turn affords more accurate control of the timing in systems in which speed information is supplied by a Hall generator 700 series models from 1985 on with the exception of the 740 with the B230A engine are fitted with camshaft driven units In the case of distributors which are not equipped with a Hall generator and as a result are fitted only with a rotor arm the timing cannot be varied by rotating the unit In systems of this type since crankshaft position signals are supplied by an inductive pick up at the flywheel only the position of the rotor in relation to the contacts
58. hereby lowered reducing the risk of detonation Knock is also prevented by enriching the mixture which has the effect of reducing the combustion temperature Knock may be caused by the following Use of a fuel with an octane rating which is too low for the compression ratio of Ihe engine Incorrect fuel air ratio If the mixture is too lean the temperature In the combustion chamber will be high despite a conslant com pression ratio A lean mixture may be due 10 a factor such as tow fuel pressure or air leakage into the induction system Excessively high combustion temperature Carbon deposits in Ihe combustion chamber will reduce the rate of heat dissipation resulting in high temperature and creating the risk of glow Ignitlon DefiCient cooling due for example to a faulty water pump radiator or thermostat or to rust lime deposits in the cooling passages Will have the same effect Incorrect or worn spark plugs The fisk of detonation will be greatly mcreased if the plug IS of the wrong type i e if the heat rating is incorrect or is it IS fouled Faulty timing The resistance to knock Will be impaired if ignition takes place too early since the cylinder pressure and tem perature will be higher under these conditions A sudden increase in engine speed What is known as transitional knock will occur if the engine speed and load are suddenly in creased If the engine is running under normal conditions of speed and
59. ific settings for a number of defined speeds and engine loads This means that the timing can be controlled to an accuracy as high 8S 8 fraction of a degree and that each ignition pulse is delivered as close as possible to the optimum point This high level of accuracy is achieved partly by the fact that the control unit interpolates between the programmed speed and load points In other words it is capable of computing an intermediate setting Furthermore the timing can be computed over a wider range and is not restricted by the type of linear functions typical of a centrifugal gov ernor The timing is computed with the aid of sensors which determine the engine load and speed This information is transmitted electrically to the control unit electronics in which details of a number of different speed and load com binations together with the appropriate timing settings are stored Prior to each ignition pulse the control unit com putes a setting which is perfectly matched to the engine running conditions prevailing at the precise instant Adjustments required by the various timing compensation functions are added to the three dimensional map 13 Group 28 Ignition systems Design and function Components Components Control unit The control unit in an electronic ignition system continuously computes the optimum timing based on information supplied by the various sensors which combine to provide the unit with an extremely accura
60. ill refuses to start commence fault tracing with operations N5 N6 and proceed to N8 NIO N2 Check timing Correct value 10 2 before TOC NOTE Timing cannot be adjusted N3 If timing is incorrect 1 Check throttle switch see NS and N7 2 Check that pulse generator leads are wired correctly to connector at bulkhead see wiring diagram 3 Open diagnostic unit cover and connect lead to socket 6 Switch on ignition Select control function 1 and display fault codes if any Press pushbutton for more than 1 second and count number of flashes Record and press again to display next fault code 3 in all Consult table N4 for interpretation of fault codes Code 111 indicates that no faults are present Check fuel system If lamp does not light when button is pressed or if no fault code is displayed proceed to NII N17 215 Group 28 Ignition systems Fault tracing Rex 145 615 TETERE TERETE DEXEXEXE 3 3 e 146 716 3 sees 3 secs y MM X FTE IEE C 3 1 4 1 216 N4 Control function 1 111 No fault 142 Control unit fault Replace unit 143 Knock sensor signal absent See N25 144 Fuel system load signal absent See N23 214 Pulse generator signal absent intermittently See N24 224 Engine temperature sensor faulty See N21 Control function 2 N5 Switch on ignition Depress button on diagnostic unit twice each time for more than 1 second lamp should commence
61. in the intake manifold 40 Group 28 Ignition systems Design and function Compensation functions Temperature sensor Function and location The control unit 1 compensates the timing for engine temperature with the aid of the temperature sensor 2 This function is used to adjust the timing at temperatures deviating from the normal operating range i e outside approx 80 C to 100 C The temperature sensor is normally mounted in the cylinder head and is completely immersed in the coolant Construction The temperature sensor consists of aconnector 3 and a body 4 provided with a male thread and enclosing one or two temperature sensitive resistors 5 with a negative temperature coefficient NTC On most fuel injected engines the device is equipped with two resistors one of which is connected to the fuel system control unit to provide a fuel enrichment signal when the engine is cold and the other to the ignition system control unit Twin resistor temper ature sensors are normally grounded to the cylinder block while the single resistor type is grounded through the control unit Signal The resistance of the temperature sensor varies in direct proponion to the coolant temperature falling as the tem perature rises Since the control unit continuously supplies the sensor with a constant current the variation in resist ance is reflected by the voltage drop across the device enabling the control unit to determine wh
62. ing has a lower thermal retention capacity and conducts a greater amount of heat away from the combustion chamber This type is normally used on engines with high specific outputs operating at relatively high combustion temperatures Plugs of this type are also known as cold plugs and feature a short in sulator nose as shown in Fig 2 Fitting a plug with the recommended heat rating will ensure that the correct working temperature is reached quick ly without the risk of overheating This also assumes that the tightening torque is within the specified limits since the thermal conductivity will be dependent on the degree of contact between the cylinder head and plug The spark gap should also be checked an excessive gap will cause the engine to miss 12 Group 28 Ignition systems Design and function General Contact breaker versus electronic systems Figure Al shows the timing curve for a contact breaker ignition system while BI illustrates the settings with which an electronic system is programmed in the form of a three dimensional map In each case both engine speed and load are taken into account when determining the setting However in contrast with the electronic system which computes the timing the contact breaker system controls it within a specified range The timing must be controlled to a high degree of accuracy to meet the demands of the modern engine for the clean est possible exhaust emissions maximum fuel economy and
63. ions are intact is displayed by pressing the accelerator to the floor The speed position pick up acknowledgement code is then displayed by releas ing the accelerator and starting the engine 65 Group 28 Ignition systems Design and function System descriptions 147 123 Diagnostic unit Construction and signals The above figures illustrate the construction of the diagnostic unit 1 its connections and the sequence of events which occurs in the course of communication between the unit and the ignition system control unit 2 during fault tracing Construction and connections Picture AI The diagnostic unit consists of an LED B a resistor R and a normally open switch pushbutton A Terminal 8 is connected to ground when the switch is closed A connection point for the coding cable 3 is provided between the resistor and switch Socket No 6 is connected to terminal 1 on the ignition system control unit Grounding ofterminal 1 is monitored by a signal transistor 4 actually a transistor network although symbolized by a single component in the figures which alternately opens and closes the ground connection across control unit ter mina 20 The signal transistor is controlled by the diagnostic circuit 5 in the control unit The battery supplies power to control unit terminal 5 and to the diagnostic circuit in the control unit This ensures that the memory is not erased when the ignition is switched off Preliminary steps
64. is essential to ensure that the working temperature is maintained within ac ceptable limits The heat is generated by the power circuit which acts as the working section of the power stage making the control circuits vulnerable to destruction In systems in which the power stage is integral with the con trol unit the former is mounted on the inside of the control unit frame to ensure adequate cooling Ignition coil The primary winding of the ignition coil in an electronic ignition system which generates extremely high voltages up to a continuous 30 kV compared with an average of 15 18 kV in a conventional coil has a relatively low resist ance Consequently coils of this type are fitted with a plug 4 which opens to relieve the pressure in the unit in the event of overheating and prevent deformation NOTE The plug muat be fitted with a protective cap in the case of acoil installed vertically in the engine compartment 17 Group 28 Ignition systems Design and function Components General Since it is not technically practical to use the control unitto regulate the relatively high current in the ignition coil pri mary this function is performed by a power stage which employs control signals from the control unit to vary both the charging time of the coil and the instant at which it delivers its high tension pulse The power stage opens and closes the primary circuit inducing a high tension voltage in the secondary each time the p
65. it 217 Connected to ground by throttle switch 198 when throttle is closed Transmits fault signals to test terminal 267 when fault tracing with test diode Receives engine speed and crankshaft position signal from Hall generator in distributor 5 Receives signal from knock sensor 218 Transmits ignition pulses to power stage 133 10 Receives 12 V supply on closure of thermostat 224 11 Grounds conlrol unit 260 12 Grounds screen of lead from Hall generator in distributor 5 13 Supplies power to Hall generator in distributor 5 14 Receives load signal from fuel system control unit 217 15 Grounds screen of knock sensor 218 lead Oone Na Power stage connections Controls current in ignition coil 4 primary winding Grounded Grounds screen of lead connected to terminal 5 Receives power from battery 1 across ignition switch 2 Receives ignition pulses from control unit 260 akhWNM 48 Group 28 Ignition systems Design and function System descriptions EZ 117K EZ 117K B230FIFT 740 B230 HFT 760 B230FT The control unit 1 computes the optimum timing based on signals from the various sensors and transmits ignition pulses to the power stage 2 at exactly the right instant At this point the power stage interrupts the current in the primary winding ofthe ignition coil 3 The high tension current induced in the secondary is delivered to the appro priate spark pl
66. livered by the piezoelectric crystal consists of acontinuous variable voltage of a frequency correspond ing to the engine vibrations The signal is fed to the control unit which computes a mean or reference value Sensing of signals The control unit is programmed specifically to detect signals of the frequency generated by knock approx 7 5 kHz The unit is provided with a measurement window in effect a specific range of crankshaft angles within which the unit is open to receive signals from the knock sensor approx 15 before TOC to approx 55 after TOC Immediately on detecting knock in a cylinder the device generates a signal which deviates significantly from the computed refer ence signal This is interpreted by the control unit as confirmation that knock has occurred After an interval of three ignition pulses in the case of 4 cylinder engines the control unit retards the ignition thereby correcting the condi tion in the individual cylinder concerned 30 Group 28 Ignition systems Design and function Compensation functions Variants The three different types of knock sensor used are illustrated above Type B is used on EZ 102K and on EZ 117K and EZ 118K systems from 1985 to 1986 Type C is used on EZ 116K systems from 1987 on as well as on EZ 117K and EZ 118K and on Rex from 1989 0n A refinement of type B this variant is fined with a sleeve 5 which ensures that the mounting force is less easil
67. livered to the plugs must be increased as the engine speed rises The speed signal is the most vital piece of information supplied to the control unit For example the engine cannot be started in this signal is unavailable The control unit also uses the engine speed to determine the point at which the ignition pulse must be delivered in relation to the position of the piston before TOG Ignition must take place earlier at higher speeds since the upward and downward movement of the pistons is faster under these conditions As a result the time available for combus tion of the fuel air mixture is less and the timing must be advanced to ensure that the mixture is burned as complete ly as possible Load information B Except in turbocharged engines the engine load varies with the vacuum in the intake manifold At low loads the throttle is only partially open and the flow of induction air is low resulting in a high vacuum At higher loads the throttle opens wider and more air is supplied to the engine Under these conditions the vacuum in the manifold ap proaches closer to atmospheric pressure as the load is increased It follows from this that a greater quantity of fuel air mixture is available for combustion as engine load increases and that the higher volume of gas produced rein forces the pressure due to compression Since the rate of combustion is accelerated by higher gas compression the timing is retarded as engine load is increased At
68. load with the timing fairly wel advanced sudden de pression of the accelerator will produce an instantaneous increase in the quantity of mixture admitted before the system has had time to adjust the timing accordingly For a brief period therefore the timing will be too advanced for the amount of mixture in the cylinders One of the functions with which the control unit is programmed limits the scope of timing adjustment to a spec ified number of degrees per crankshaft revolution 29 Group 28 Ignition systems Design and function Compensation functions 147 095 Knock sensor Function The knock sensor 1 is used to detect engine knock enabling the control unit 2 to take the appropriate action by re tarding the ignition Construction The knock sensor see picture C consists of a casing 3 housing a piezoelectric crystal 4 mounted on a threaded sleeve 5 between two connector strips 6 One side of the assembly is fitted with a damping weight 7 and spring washer 8 secured by a nut 9 Operation Mounted on the cylinder block the sensor detects the vibration caused by knock Since the device employs a piezo electric crystal lin which a potential gradient is set up when the material is subjected to strain the sensor develops its own signal The vibrations caused by knock produce an instantaneous pressure on the bottom of the sensor which responds by generating an output voltage Signal The signal de
69. load signal Ihe control unit modifies the timing on the basis of the speed signals which it receives and oper ates in accordance with the pre programmed full load timing selling when the idling switch has opened If the knock sensor signal is lost the conlrol unit computes the timing setting on Ihe basis of a fail safe retardation of approx 10 The control unil electronics must not be exposed to excessively high temperatures For example removal of the unit prior to the completion of the stoving process during manufacture may result in its destruction Because of its sensitivity to temperature the unit is normally installed in a location well protected from engine heal 15 Group 28 Ignition systems Design and function Components Control unit power stage and ignition coil configurations The control unit power stage and ignition coil configuration may take one of four different forms As a general rule the control unit delivers ignition pulses to the power stage which controls the current in the pri mary winding of the ignition coil in response to signals from the various sensors and pick ups A high tension volt age is induced in the secondary and fed to the distributor which delivers it to the appropriate spark plug generating a spark across the eleClrodes and igniting the fuel air mixture A The control unit power stage and ignition coil may all be separate components This applies to EZ K systems B The cont
70. low engine loads on the other hand the timing may be advanced to compensate for the lower rate of combustion and to improve fuel utilization Crankshaft position information C The crankshaft position i e angle provides information on the position of each piston in relation to TOC This in formation is essential to the system control functions which compute the timing continuously on this basis Group 28 Ignition systems Design and function General Fig 1 Hot plug Fig 2 Cold plug Spark plugs Use of the correct type of spark plug correctly installed and replaced at the recommended intervals is essential to the satisfactory operation of the ignition system Assuming the engine to be in good condition ad herence to these recommendations will ensure maximum plug life making the component one of the most re liable in the ignition system In this context it may be of interest to consider some of the demands imposed on the spark plugs and to discuss a number of concepts As the means used to ignite the mixture in the combustion chamber the spark plug initiates the combustion pro cess The plugs are designed to supply up to approx 25 sparks per second per cylinder at 6000 rlmin in a 4 cylinder engine from a high tension source which in the case of electronic ignition systems often operates at over 30 kV Spark plugs must be capable of withstanding the extremely rapid temperature and pressure fluctuations whi
71. may result Take care to ensure that locking pin does not fall into distributor Remove circlip Hall generator retaining screws plastic pin A securing connector 139 822 129 Group 28 Ignition systems Fault tracing TZ 28H Turn Hall generator counterclockwise as far as pos sible Release and remove vacuum advance unit lift Hall generator unit and connector out of distrib utor 139 776 Reassemble distributor Install Hall generator unit and connector in distributor and secure loosely with two screws Mount circlip Screws are of different lengths Zh 1 28mm 31 2 6 mm 24 325mm 20 139 824 139 821 Turn generator element counterclockwise Hook vacuum advance unit rod over spigot on Hall generator plate J PARARE ge t andata N 130 Group 28 Ignition systems Fault trBcing TZ 28H Insert and tighten all screws Insert connector securing pin 1 Install trigger rotor 2 locking pin 3 circlip 4 Install distributor Ensure that No 1 eylinder is at TOe Turn rotor arm clockwise about BO from mark on dis tributor housing Place distributor in position Rotor arm should now be aligned with mark on dis tributor housing Remove rotor arm InstaU moisture shield plastic cover rotor arm distributor cap 131 Group 28 Ignition systems Fault tracing EZ 102K H Fault tracing EZ 102K The
72. meters such as engine load and speed are available for immediate use by the microprocessor Microprocessor c The microprocessor C receives the digital signals from the converter Depending on the signal configuration the device selects the memory program which best meets the needs of the prevailing running conditions 14 Group 28 Ignition systems Design and function Components Output unit D The digital information supplied by the microprocessor is fed 10 the output unit D for conversion into the ignition pulses fed to the power stage This may either be an integral part of the control unit or a separate unit Depending on the program selected at the particular instant the control unit determines the point at which the igni tion pulse must be delivered to the power stage The latter controls the current in the primary winding ofthe ignition coil in response to the signals from the output unit Voltage stabilizer The control unitis powered by a 12 V supply However since the bahery voltage is too high for the internal integrated circuits a voltage stabilizer is used to produce a stabilized 5 V supply for these Engine speed limitation All control units are programmed with some type of speed limiting function On Bendix systems the control unit normally commands the power stage to reduce the Ignition coil charging period producing a weaker spark which limils the engine output On EZ K systems Ihe conlroi unit uses Ihe po
73. ne does not utilize the full energy content of the fuel Although the concentrations of unde sirable constituents such as HC CO NO and NO are lower under these conditions the engine requires more fuel to deliver the same output producing a greater total volume of exhaust gases Effects on cylinder and exhaust gas temperatures Advancing the ignition i e generating the spark to ignite the fuel air mixture when the piston is further from ToC produces a higher combustion temperature and a lower exhaust gas temperature than when the timing is retarded This is due to the fact that the compression produced by upward movement of the piston reinforces the pressure wave developed by the flame front causing the cylinder pressure and temperature to increase The lower exhaust gas temperature is explained by the somewhat longer interval between the completion of combustion and the open ing of the exhaust valve Retarding the ignition generating the spark when the piston is closer to TDC produces a lower combustion tem per ature but a higher exhaust gas temperature than when the timing is advanced Underthese conditions a higher pro portion of the energy is released during the expansion stroke when the piston is moving downwards reducing the maximum temperature somewhat The higher exhaust gas temperature is explained by the shorter interval between the completion of combustion and the opening of the exhaust valve NOTE It isimportantthatthe
74. nerator in the distributor 5 and ensures that the ignition coil is fully charged between pulses The control unit also features a standing current cut off function which prevents overheating of the ignition coil by interrupting the current if no speed signals are present Control unit connections Controls ignition coil 4 primary current Ground terminal Hall generator ground terminal Power supply 12 V Hall generator power supply 12 VI Receives engine speed and crankshaft position signals from Hall generator Ook ON 44 Group 28 Ignition systems Design and function System descriptions RENIX F RENIX F B200K The above illustration and the following text are based on the B200K engine used in the 740 The system consists of an electronic control unit 1 which is supplied with engine speed and crankshaft position sig nals by an inductive speed position pick up 2 The pick up detects the passage of a number of teeth on the fly wheel 3 The control unit is also supplied with information on engine load through a vacuum line 4 connected to the intake manifold the pressure in which actuates a vacuum advance unit 5 integral with the unit The speed and load signals are processed by the control unit electronics and compared with the timing settings stored in the memory Having used the information to compute the optimum timing the unit transmits control sig nals to an integral power stage which makes and bre
75. ng of the input and output signals the manner in which the components are connected and the function purpose of each is essential to an understanding of the types of fault which may arise and to ensuring that the correct diagnosis is made in each case Sensors and pick ups providing fast and precise information on the prevailing running conditions are vital to ensure that the electronics control the working components of the system reliably and accurately This manual deals with the electronic ignition systems used by Volvo on its 700 series models in terms of design and function as well as fault tracing repair and maintenance The first part of the manual consists of a description of the features components and compensation functions common to the various systems followed by a description of each individual system and some of the special functions peculiar to each The appropriate wiring diagrams are in cluded Group 28 Ignit on systems Design and function Overview Review of electronic ignition systems 147 077 The above figure shows the major components of each of the systems described below Summary Control system The control unit A houses the electronic circuits and the various program functions needed to compute the timing The power stage Bl controls the primary current in the ignition coil in response to control signals from the control unit The power stage may either be an integral part of the control
76. o report a fault stored in the memory or confirm operation of a switch The arrows in this picture indicate that the direction of signal flow is from the control unit to the diagnostic unit The diagnostic circuit controls the operation of the signal transistor To produce a flash the circuit activates the tran sistor connecting terminal 1 on the control unitto ground across terminal 20 Current then flows through the ignition switch and diagnostic unit to control unitterminal 1and to ground across terminal 20 causing the LED to light i e to produce one flash of the particular digiti Immediately after this when the LED has been extinguished the signal transistor opens the terminal 1 ground connection and the cycle is repeated until the three digit code for the partic ular fault or acknowledgement code has been completed If the self diagnostic function has been selected the diagnostic circuit must be supplied with information on when the next fault code isto be displayed The control unit receives this information in the form ofthe new signal which is initiated when the voltage at terminal 1 falls to zero as pushbutton A is again depressed 67 Group 28 Ignition systems Test equipment Test equipment 999 Description application 280 6480 652 9724 992 68 Test diode for connection to diagnostic unit to indicate certain types of fault Voltmeter ammeter for voltage and currenl measurement Multimeter for voltage
77. oe ioe has eee see Sn ete 167 168 EZ 117K1118K EE Sh ashe acre canes 182 186 EZ 116K es act 198 200 213 214 Rex4 oo cece eee esee I E 225 226 227
78. of adaptive timing retardation Representing a period of approx 10 minutes during which the function is activated interval lal is termed the active adaptive zone If the control unit detects that the speedlload increase is of a permanent nature before the adaptive zone is reached the basic timing will be retarded by 1 The function is activated in the event of knock i e the basic timing is retarded as indicated by the start of interval a in the figure In this case the timing is retarded by 4 to 4 or 1 more than under normal knock conditions following which it is re advanced in the usual manner at a rate which varies with engine speed to 1 below the basic setting a _ 0 37 Group 28 Ignition systems Design and function Compensation functions If the load temporarily reverts to normal b during the adaptive retardation period e g if the trailer is uncoupled or the road becomes downhill the timing will be returned to the basic setting a If engine speed and load sub sequently change within the 10 minute period so that conditions once more fall within the knock sensitive zone c the control unit will again automatically retard the timing by 1 without the occurrence of knock If knock persists despite the intervention of the adaptive retardation function the timing will be retarded as usual as indicated by the dashed downward steps i e by 3 each time knock occurs The control unit always leav
79. ofite The greatest care must be taken when replacing the flywheel carrier plate if the component has been dismantled e g as part of gearbox replacement On 4 cylinder engines it is possible to replace the component in the wrong position thereby altering the timing The timing will be altered by approx 3 if the pick up leads are reversed Although the magnitude of the induced voltage will increase with flywheel speed the voltage regulator in the control unit en sures that the voltage supplied to the le circuits remains constant 23 Group 28 Ignition systems Design and function Speed and crankshaft position information Ni 1 he y TOC TOC Flywheel carrier plate profiles The above figures show the three different loothed or drilled crankshaft carrier plate profiles which are used The profiles afe shown in section Unlike the starter motor ring gear which is mounted on the flywheel the profile used for signal generation is usually an integral part of the component Volvo ignition systems are supplied mainly by two manufacturers Bosch of Germany and Bendix France Among other factors this means that several different profiles must be used while the method whereby the control unit de tects and processes the inductive pick up signals may also differ The electronic circuit which may be likened to a frequency divider or multiplier in which the signal is first received and processed also va
80. on signal Engine knock is indicated by a knock sensor 26 Closure of the throttle is indicated by a throttle switch 19 mounted on the throttle cable pulley On models equipped with AC operation of the compressor 28 is indicated by a signal from the electromagnetic clutch The selection of a drive position on automatic models is indicated by a signal from the starting interlock switch 27 via a relay Engine temperature is measured by a temperature sensor 201 in the cylinder head B230K only Group 28 Ignition systems Design and function System descriptions EZ 118K 147 112 EZ 1 18K Idling compensation EZ 118K may be provided with one or two idling compensation functions ifthe car is equipped with automatic trans mission and or air conditioning If either function is activated he control unit will advance the timing at idling by 8 to compensate for the higher engine load A Certain models equipped with automatic transmission are provided with a function which advances the timing when a drive position is selected to compensate for the increased load imposed by the torque converter The starting interlock switch 21 opens the relay coil 22 ground connection when the gear selector is moved to position R D 2or 1 This closes the relay contacts supplying 12 V to the timing advance terminal on the control unit 1 The control unit will advance the timing ifthe idling air control switch 19 also indicates t
81. or Spark at ignition coil Yes Check rotor distributor cap and HT leads Correct faults as required No Ignition system fault Switch off ignition Group 28 Ignition systems Fault tracing EZ 102K Fault tracing EZ 102K HI Check security of ground leads at terminals on intake manifold twin black leads 137 273 H2 Check LT supply to ignition coil and power stage Switch on ignition Measure voltage between ignition 15 coil terminal 15 and ground Voltmeter reading should be approx 12 V If vottage 0 V Open circuit in lead from central electrical unit See wiring diagram 139 788 H3 Disconnect power stage connector Pull back connector sleeve and connect instrument to rear of connector Measurement from front may dam age terminals resulting in looseness and poor contact Check that voltage across each of connector terminals 1 and 4 and ground is approx 12 V Measure individu ally between each terminal and ground gay If vottage 0 V N Open circuit in lead from central electrical unit See 4 wiring diagram Switch off ignition 143 266 137 Group 28 Ignition systems Fault tracing EZ 102K 1 HE 143 266 138 H4 Check ignition coil primary winding and leads Measure resistance between terminals 1 and 4 in power unit connector This is equivalent of measuring resistance across ignition coil terminals 1 and 15 in cluding leads See wiring diagram
82. or signal the control unit can apply timing compensation by retarding the ignition when the engine is cold to achieve faster heating of the coolant and by advancing it when the engine tends to run too hot The system appeared in 1987 with the introduction of the 8280 engine to replace the B28 and is therefore used only on the 760 780 EZ 1 15K is used in combination with LH Jetronic 2 2 on both the E and F variants EZ 116K is a refinement of other EZ K systems However it features advanced self diagnostics which facilitate fault tracing and monitoring The control unit continuously monitors the various sensors and functions and any faults present may be displayed with the aid of a diagnostic unit mounted in the engine compartment EZ 116K was in troduced in 1988 on the 16 valve 8234F engine used in the 740 GIT Unlike other EZ K systems used on 4 cylinder engines in the 700 series EZ 116K is equipped with an inductive speedJposition pick up mounted close to the fly wheel instead of a Hall generator in the distributor The system is used in combination with the very latest fuel in jection system LH Jetronic 2 41 Manufactured by 8endix the Rex I system is equipped with the same type of diagnostic system as EZ 116K Used in conjunction with the Regina fuel injection system Rex was introduced in 1989 on 8230 F engines sold in the USA Compensation functions However most electronic ignition systems are equipped with additional sensors whi
83. otal advance distributor degrees Advance commences at vacuum mm Hg Settings 1 at vacuum mm Hg Max advance at vacuum mm Hg B19ET Direction of advance l l eee llle Leste Total advance Advance commences at vacuum mm Hg tissues Settings 50at vacuum mm Hg 2 at vacuum mm Hg T Max advance at vacuum mm Hg Direction of advance Total advance distributor degrees Advance commences at vacuum mm Hg Settings 1 at vacuum mm Hg Max advance at vacuum mm Hg d B28A E Direction of advance Total advance Advance commences at vacuum mm Hg Settings 50at vacuum mm Hg 2 at vacuum mm Hg gg etree AAS Max advance at vacuum mm Hg Direction of advance Total advance distributor degrees Advance commences at vacuum mm Hg Settings 1 at vacuum mm Hg Max advance at vacuum mm Hg B28F Direction of advance Total advance Advance commences at vacuum mm Hg Settings 50at vacuum mm Hg 2 at vacuum mm Hg Max advance at vacuum mm Hg s Direction of advance Total advance distributor degre rees jean auda Advance commences at vacuum mm Hg Settings 1 at vacuum mm Hg e Max advance at vacuum mm Hg Specifications 16 5 20 5 1000 1250 25 29 1500 1750 31 7 1900 Positive 7 5t1 105 140 2 03 2 70 in Hg 175 215 3 38 4 15 in Hg 235 4 54 in
84. ough lead is intact internal fault is present in one of control units Replace panels and glove compartment 221 Group 28 Ignition systems Fault tracing Hex 146 117 144 811 144 818 144 819 222 N24 Check pulse generator Measure resistance between connector terminals 10 red and 23 blue Resistance should be approx 240 25 ohm Check that screen is connected to terminal 11 N25 Check knock sensor leads Undo knock sensor connector and bridge terminals 1 and 2 Measure resistance between terminal 12 black and 13 green in control unit connector Resistance should be o ohm If resistance is too high o one or both leads is faulty open circuited Remove jumper and measure each lead separately with ohmmeter Replace damaged lead s If leads are intact replace knock sensor Tightening torque 20 5 Nm 1523 5 ft Ib Reconnect knock sensor connector Group 28 Ignition systems Fault tracing Rex l N26 Check ignition coil and power stage 4201 Undo connectors Separate ignition coil from power stage Remove both mounting screws with a Torx TX 215 screwdriver and lift off ignition coil N27 Measure resistance across ignition coil terminals Measure resistance across LT terminals and as il lustrated Resistance should be approx 0 5 ohm Measure resistance between HT terminal and each LT terminal Resistance should be approx
85. ounds one of the switch terminals al lowing a current to flow from one of the terminals on the control unit The ground current is interpreted by the con trol unit to determine on the basis of engine speed information whether the conditions are those of idling or engine braking Idling At speeds close to idling the signal causes the control unit to adopt a fixed ignition setting in accordance with the idling program Since the engine is not required to develop a specific power when idling the timing is determined mainly on the basis of maximum comfort This means that the setting is well retarded between approx 10 and 16 before ToC to minimize the peak i e maximum pressure in the combustion chamber during the combustion phase ensuring smooth steady running Engine braking Since the speed is higher under engine braking conditions the control unit timing characteristic is speed dependent only In general the characteristic represents an optimum compromise between the lowest possible emissions and minimum fuel consumption Most ofthe electronic fuel injection systems used feature a fuel cut off function which intervenes under engine brak ing conditions In this case the fuel system control unit is also supplied with a fUIly closed throttle signal and keeps the injectors fully closed under these conditions Throttle switch types A Practically all fuel injected models in the 700 series are fined with the type of throttle s
86. pprox 10 16 in the case of EZ K systems Ae advance following correction of knock After knock has been eliminated the control unit maintains the retarded setting for a specified number of engine rev olutions depending on the speed applies to EZ K systems before re advancing the ignition in small steps 0 1 1 either until the original characteristic has been restored or until the engine again starts to knock The maximum retardation must not deviate excessively from the basic setting if an excessive rise in exhaust gas temperature is to be avoided Information on engine speed andfor load is also essential to enable the control unit to impose the maximum retarda tion if necessary 32 Group 28 Ignition systems Design and function Compensation functions Timing compensation applied by different ignition systems to correct knock Fig 3 x basic timing as computed a max knock controlled retardation b knock retardation step c re advance step d re advance interval The following is a summary of the compensation values applied by the various systems in the event of knock EZ I02K Max knock controlled retardation Knock retardation step Re advance step Re advance interval EZ I17K Max knock controlled retardation Knock retardation step Re advance step Re advance interval 9 8 2 8 0 35 Specified number of engine revolutions depending on speed 13 B230F 9 8 B230FT 2 8
87. re sensor resistance directly 10 determine whether sensor or lead is faulty Replace sensor or lead as appropriate gH 2 Fe A PEER 143 282 220 137 254 Rex I Regina 146 719 Group 28 Ignition systems Fault tracing Rex J N22 Check throttle switch Measure resistance between control unit connector terminal 7 orange and ground Resistance should be a ohm Depress accelerator until throttle switch opens slightly Resistance should increase to infinity In case of fault Measure throttle switch resistance di rectly to establish whether fault is in wiring or switch itself If necessary Check throttle switch setting Open throttle slightly and listen to switch Click should be heard as idling contacts open immediately throttle opens Adjustment Loosen mounting screws 3 mm Allen screws Turn switch slightly clockwise Turn switch back counterclockwise until click is heard from contacts Tighten screws Check adjustment N23 Check load signal from fuel system control unit Remove panel under right hand side of instrument panel and panel at right hand side of bulkhead Re move glove compartment Undo fuel system control unit connector Measure resistance between ignition system connec tor terminal 8 yellow and fuel system connector ter minal 25 yellow Instrument should read 0 ohm otherwise lead is open circuited Check connectors as per wiring diagram If fault persists alth
88. reo quired 217 Group 28 lenition systems Fault tracing Rex 2 8 138 110 144 807 Inspection end checking N71 Undo control unit connector Caution The ignition must be switched off whenever the connector is disconnected or reconnect ed Remove panel under leh hand side of instrument panel Release connector catch and separate connector from control unit N12 Remove protective cover from connector Caution Never insert instrument probes into front of connector terminals This may cause dam age which will aggravate any faults present Always connect probes to terminals through holes in connector side taking care to avoid unnecessary force Terminal numbers are marked on side of connector N 13 Check that all terminal sockets are at same height in connector Poor contact may result one terminal socket is lower than the others N14 Check bushar 30 supply Measure voltage between control unit connector termi nal 5 brown and ground Reading should be approx 12 V If no reading is indicated check lead between control unit sleeve and busbar 30 supply at fuseholder 143 463 Group 28 Ignition systems Fault tracing Rex l N15 Checking diagnostic unit Switch on ignition Connect test lead to socket 6 Measure voltage between control unit connector termi nail yellow red and ground Instrument should read approx 12 V Depress pushbutton Voltmeter should now read 0
89. ries in design The frequency of the incoming voltage pulses is divided by a certain factor to improve signal resolution This in turn means that the control unil can regulate the timing in more precise steps for example when re advancing the timing after knock in a cylinder has been eliminated A 24 Ignition systems supplied by Bendix employ a type 4412 toothed profile The figure 44 means that the flywheel is provided with 44 drilled holes and the figure 2 that it has two long teeth each equal in length to two shorter teeth In other words the profile is provided with 40 44 2x2 short teeth and two long teeth The angular pitch be tween two adjacent short teeth XO is 8 18 360744 The two long teeth which comprise the crankshaft position reference points are located 180 apart angle a The control unit identifies TDC as the point 90 after the passage of a long tooth The type 44 2 profile is used on Aenix F and Rex l systems In each case the control unit applies a factor of 8 18to improve the signal resolution This means that it can adjust the timing in steps of 1 0 Ignition systems supplied by Bosch for Volvo 4 cylinder engines feature a type 60 1 toothed profile This means that the profile is provided with 60 drilled holes and with one long tooth of twice the length of a short tooth In other words the profile is provided with 58 60 1x2 short teeth and one long tooth which represents the crank shaft position
90. rimary current is in terrupted Construction The power stage 1 and ignition coil 2 are assembled by means of screws enabling the units to be replaced indi vidually The power stage receives control signals from the control unit green lead across the two pole centre con nector 3 which is also used to ground the signal The three pole connector 4 on the right supplies the power stage and ignition coil wilh battery voltage grounds the coil and supplies the rev counter with a signal The connec tor 5 on the left is not used The power stage 1 incorporates the electrical circuits which control the primary current in the ignition coil Mount ed on a bracket in the engine compartment the power stagelignition coil assembly is provided with a large contact area with the suspension strut housing to ensure that the heat generated is diSSipated The ignition coil 2 is of the conventional type with a primary and secondary wiring The high tension induced in the secondary is fed to the distributor from terminal 6 As on most modern ignition systems the HT voltage is ofthe order of 30 kV Standing current protection A function known as standing current protection is provided 10 prevent overheating of the ignition coil when the ig nition is switch ed on with the engine at rest When the engine is stopped the control unit receives no speed signals and delivers a low control signal to the power stage which responds by opening t
91. rized systems RENIX F The name is a trademark of the Bendix company In this system the control unit power stage and ignition coil comprise a single unit Since 985 Renix F has been used on 7405 equipped with the B 200 K engine and Salex carburettor The letters used in the deSignations 01 the various systems are usually derived from the maker s native language while the fig ures usually denote the verSion and or variant designation Group 28 Ignition systems Design and function Overview Review of electronic ignition systems Il Type EZ K and Rex l The illustration shows the main components of type EZ K and Aex l ignition systems Common features An abbreviation of the German term Elektronischer Zundung mit Klopfregulung roughly Electronic ignition with knock sensor the designation EZ K describes a group of systems manufactured by the Bosch company The various systems in the EZ K group are relatively similar in terms of functions and components All feature microprocessor control and incorporate a memory which is programmed with a family of ideal timing curves for the particular en gine Each system also includes a sensor which detects engine knock and retards the ignition in response to a mem ory program which is individual to each cylinder This means that the timing in each cylinder may vary at any given instant As column E indicates systems in this group are normally supplied with engine load
92. rol unit and power stage may be combined in a single unit with a separate ignition coil This applies to TZ 28H C The power stage and ignition coil may be combined with the control unit separate This applies to Rex l O The control unit power stage and ignition coil may comprise a single unit Although the TZ 28H control unit does incorporate a number of CirCUits additional to those used in EZ K power slages ils pri mary function is closer 10 thal of a power stage and the term conlrol unit is somewhat misleading 16 Group 28 Ignition systems Design and function Components Power stage and ignition coil Function of power stage The power stage 1 functions as an electronic switch controlling the current in the ignition coil on command from the control unit 31 The illustration shows the components of an EZ K system In the Renix F system the power stage is integral with the control unit although the principle of operation is the same The function ofthe power stage is analogous to that of the points in a mechanical ignition system in that it alternate ly opens and closes the coil primary ground connection Each time a cylinder fires the power stage interrupts the current in the primary inducing a high tension voltage in the secondary Control signal Once the control unit has computed atiming setting based on the signals from the various sensors the value is con verted into a control signal for the po
93. rottle is closed The solenoid valve operates to cut off the supply of fuel with the aid of a vacuum valve mounted on the carburettor The control unit grounds the solenoid valve thereby activating the fuel cut off function when the engine speed is higher than approx 1650 r min 1610 r min on 1985 86 models and 1700 r min on 1987 and later models and the idling switch is closed The ground connection is opened and the fuel supply is restored when the engine speed has fallen to approx 1550 r min or when the accelerator is depressed The fuel cut off function operates only if the engine temperature is higher than approx 85 C The fuel cut off function reduces the fuel consumption and as a result the volume of exhaust gases The idling switch was transferred from the accelerator pedal to the thronle pulley in 1987 the same year in which the EZ 118K control unit for the B 230 K engine was programmed with new timing Curves as part of the redesign of the combustion chamber On its introduction the new engine was designated B 230 KH the H standing lor Heron In the service literature K engines are now identified bV stating the year for example B 230 K 1987 53 Group 28 Ignition systems Design and function System descriptions EZ 118K 141114 Control unit connections 3 Supplies fault indication signals to test terminal 267 when test diode is connected 4 Supplies power to Hall generator in distributor 5 6 Recei
94. round Signal A In this position the magnetic field is blocked by the trigger rotor vane and the Hall effect is absent No voltage is induced in the Halt IC element and the ground connection remains open As aresult a 5 V signal is present atter minal 01 B In this position the rotor exposes the Hall IC element to the influence of the magnetic field and the resultant Hall voltage is fed to the transistor amplifier The 5 V signal at terminal 0 is then connected to ground across the terminal and the voltage at 0 falls to O V Thus the signal from the Hall generator varies between 0 and 5 V in the form of a square wave signal the control unit deriving its engine speed information from measurement of the duration of the alternating half waves The crankshaft position signal is obtained by adjusting the basic setting of the distributor to coincide with the positive flank of the Hall generator signal i e the half wave generated when the rotor blocks the magnetic field a few crankshaft degrees before TDC 20 At A2 Group 28 Ignition systems Design and function Speed and crankshah position information 5V S OV M A2 Signal increases from 0 to 5 V Control unit starts to compule timing of ne I ignition pulse Signal falls from 5 to 0 V Conlrol unit commences ignition counldown and delivers ignition pulse as computed Positive flank Hall element unaffected by magnetic field Negative flank Hall elemen
95. s manual Should the signals from the knock sensor be lost for any reason most of the control units will retard the ignition by a pre programmed fail safe value 01 approx 10 31 Group 28 Ignition systems Design and function Compensation functions c 1 0 _60 ge 7 0 _ 60 O gO Knock control The knock sensor moniiors the combustion process continuously If knock occurs the device delivers a special sig nal to the control unit which takes corrective action by retarding the ignition in the cylinder affected Knock control characteristic The principle of knock control is more or less the same in the case of all systems equipped with knock sensors Al though the knock control characteristic shown is that for the EZ 115K system the description is generally applica ble The vertical coordinate shows the ignition setting in degrees in relation to the basic timing indicated here by the angle x while the horizontal coordinate is the time scale which normally varies with engine speed Stepped control The control unit continuously computes the optimum timing on the basis of the running conditions On detecting knock the unit retards the ignition by a step of a few degrees 2 3 depending on the system in the cylinder affected If the phenomenon persists the setting is retarded by a further step and so on until the condition has been correct ed The maximum retardation in relation to the basic timing is a
96. s ignition pulses to power stage 4191 17 Transmits speed signal to fuel system IH 2 2 control unit 217 20 Grounds control unit 2601 24 Receives engine speed crankshaft position signal from Hall generator in distributor 5 Power stage connections Controls current in ignition coil 4 primary winding Grounded Grounds screen of lead connected to terminal 5 Receives power from battery 1 across ignition switch 2 Receives ignition pulses from control unit 260 o RON 50 Group 28 Ignition systems Design and function System descriptions EZ 118K EZ 118K B200E B230E and B230K The control unit 11 computes the optimum timing on the basis of information from the various sensors and trans mits the necessary ignition pulses 10 the power stage 21 which controls Ihe current in the primary winding ofthe ig nition coil 3 The high tension current induced in the secondary winding by interruption of the primary is fed to the distributor 4 for delivery to the appropriate spark plug 5 Variants for the B230 K engine also supply signals to a solenoid valve 25 controlling the fuel cut off function under engine braking conditions The timing selting computed by the control unit is based on the following information An engine load signal is supplied by a vacuum line 12 between the control unit and the intake manifold A Hall generator in the distributor 4 supplies an engine speed crankshaft positi
97. s in 1985 The 8230 FT variant features a knock controlled fuel enrichment function Like its predecessor EZ 102K the turbo engine variant is equipped with a thermostat which activates a timing advance function to protect the engine from over heating EZ 118K differs most from the other systems in the group due to the fact that it depends on avacuum connection be tween the intake manifold and control unit to supply engine load information rather than on a load signal supplied by an air mass meter via the fuel system control unit The system also employs an idling switch mounted on the throttle pulley rather than a switch mounted on the throttle housing EZ 118K was introduced in 1985 on the B200 E 8230 E and B230 K engines Two idling compensation functions may be used on all EZ 1 18K variants The 8230 K variants are equipped with a temperature sensor while the control unit operates a solenoid valve which interrupts the fuel supply under engine braking conditions Most ofthe differences are attributable to the fact that the system is used on carburated engines now with Pierburg carburettors and on E engines with the Cl system K Jetronicl EZ 115K has been designed especially for the 8280 engine Its features include two knock sensors one for each bank of cylinders a position detector for No 1 cylinder a knock controlled fuel enrichment function and an inductive speedJposition pick up mounted at the flywheel Depending on the temperature sens
98. s of signals which describe the engine running conditions The control unit uses the signals to compute the optimum timing and transmits the necessary ignition pulses to the power stage 2 which makes and breaks the current in the primary winding of the ignition coil 3 The high tension current thereby induced in the secondary winding is delivered to the appropriate spark plug 4 by the distributor 5 The timing is computed by the control unit on the basis of the following information The Hall generator in the distributor 5 supplies a signal indicating the engine speed and crankshaft position The engine load signal is supplied by the LH 2 1 injection system control unit 9 which in turn is supplied with a load signal by the air mass meter 10 Any tendency ofthe engine to run hot is indicated by a thermostat 8 The throttle must be closed and the engine temperature must be above 103 C before the control unit advances the timing Under these conditions the ther mostat will close and the control unit will both advance the setting by 13 and switch in the electric radiator fan Engine knock is indicated by the knock sensor 7 Throttle closure is indicated by the throttle switch 6 47 Group 28 Ignition systems Design and function System descriptions EZ 102K 147 108 Control unit connections Receives power from battery 1 Ihrough ignition switch 2 Transmits speed signal to fuel system control un
99. t illustration The various signals engine speed crankshaft position and enQine load comprise information which is used by ignition systems of all types to compute the timing Group 28 Ignition systems Design and function Overview Review of electronic ignition systems TSZ An electronic ignition system in which the function performed by contact breaker points in conventional sys tems is carried out by an inductive pulse generator Roughly translated the abbreviation TSZ which stands for Transistor Spolen lundung means Transistorized coil ignition The pulse generator signals are transmitted to a control unit which regulates the coil charging period The system also incorporates a centrifugal generator and a baltast resistor Designated TSl 4 the variant for 6 cylinder engines B28A1EiF was used on 700 series cars from 1982 to 1986 TZ 28H As the designation indicates this is atransistorized system employing a Hall generator to supply the signals used by the control unit to control the primary current in the ignition coil A vacuum advance unit on the distributor varies the timing with engine load Although the system was used on some 700 series models produced in 1984 it was almost completely superseded by other systems in 1985 as the new family of engines entered production Un like other systems discussed in this context TZ 28H is not fully electronic indeed it is usually regarded as one of the group of transisto
100. t influenced by magnetic field A Hall generalor is used on TZ 28H with a 12 V reference signal EZ I02K EZ 117K and EZ 118K systems 21 Group 28 Ignition systems Design and function Speed and crankshaft position information Inductive speed position pick up 147 090 Function and location The purpose of the speed position pick up 1 is to supply the control unit 3 with information on engine speed and crankshah position The pick up is mounted close to the flywheel 2 or carrier plate on automatic models the periphery of which is provided with a series of drilled holes The location of the pick up is such that it is influenced by this configuration of holes Construction A The pick up 1 consists of a permanent magnet 4 a pole tip b which concentrates the magnetic field at the end of the device and acoil 6 The magnet creates a magnetic field which varies in strength depending on whether a hole or tooth is passing the tip Operation An alternating voltage is induced in the pick up coil when one of the projections or teeth on the flywheel passes the tip This variable signal is transmitted by a lead to the control unit In effect therefore the pick up supplies the control unit with a unique alternating voltage an electrical picture of the flywheel from which the unit can determine both the engine speed and crankshah position Signal B The frequency 7 of the signal i e the period between two s
101. te picture of engine run ning conditions The control unit receives immediate notice of any change in the conditions under which the engine is powering the car enabling it to compute a new setting instantaneously Once this has been completed in an oper ation taking as little as a thousandth of a second the unit delivers an ignition pulse to the power stage The control unit consists of a number of electronic components In simplified terms these consist of four main ele ments converter A memory B microprocessor chip C and output unit D Converter A The converter A receives information from the sensors and converts the signals into digital numerical form Some of the sensors supply analogue signals such as the temperature dependent change in resistance typical of a temperature sensor while the signal transmitted by others depends on whether or not a voltage is present as in the case of athrottle switch The sensors may also transmit signals in the form of voltage pulses like an inductive pick up or a variable frequency voltage like a load signal vacuum converter All of these electrical signals whether in the form of a single variable voltage or a series of voltage pulses are converted into standard digital form by the converter the outputs from which are used by the microprocessor and memory Memory B All programs and pre programmed values are stored in the memory B in which all possible values of para
102. test function Oispl8y codes A red LED B is located on the diagnostic unit beside the pushbutton The LED displays a series of flashing codes to indicate any faults which may be present in the system when the appropriate test function has been activated The code 2 1 4 is illustrated in Fig C above As the illustration shows the code consists of a 3 digit number each digit of which is indicated by flashing of the LED in rapid succession at intervals of approx 0 5 seconds The interval be tween each series of flashes which comprises an individual digit is approx 2 5 seconds NOTE Once the self diagnostic function has been selected a fault code will be displayed if a system component or its wiring is faulty On the other hand when the functional test program is selected the LED will display a code confirming that the switch and wiring under test are fault free Self diagnostic function The self diagnostic function monitors the same types of fault as those stored in the control unit memory The con trol unit continuously monitors a number of the components and circuits connected to it detecting and storing any faults which may occur The memory accommodates a total of three different faults although the LED on the diag nostic unit can display up to seven 3 digit fault codes NOTE The memory will be erased and the fault codes cancalled if the battery is disconnectedl 63 Group 28 Ignition systems Design and function System
103. this case that speed and load are constant hence the extremely simplified straight yellow line The vertical axis indicates the extent to which the timing has been retard ed in relation to the normal setting a The horizontal axis indicates the time as defined by a certain number of en gine revolutions Knock retardation is illustrated by the downward steps red and re advance by the smaller upward steps upwards blue The maximum retardation is 15 here denoted by a 15 Knock controlled retardation When the engine is running the control unit computes the optimum ignition timing on the basis of speed and load signals The occurrence of knock in a cylinder is detected by the control unit which retards the ignition by a step of 3 in the cylinder in question If the phenomenon persists the control unit retards the ignition by a further step of 3 In 6 and so on until knock is eliminated Ae advance at different rates Re advance of the ignition to the normal setting a or until knock again occurs takes place at different rates depend ing on engine speed However the steps are equal in magnitude in all cases representing an advance of 1 at atime Once the timing has been retarded to a 3 or morel a the succeeding re advance steps b are performed twice as fast Thus the interval a in the figure is twice as long as b At high engine speed the interval a during which the timing is retarded to a 3 or mor
104. uccessive voltage peaks is a measure of the engine speed To provide a reference signal for the crankshah position one or more teeth one or two in the case of 4 cylinder engines and three on 6 cylinder units on the flywheel carrier plate are made longer than the others The control unit detects the crankshaft position by sensing the interruption in signal 8 which occurs as a long tooth passes the pick up This reference signal is used to determine the top dead centre TOC position Group 28 Ignition systems Design and function Speed and crankshaft position information Advantages Ignition systems employing inductive speed position pick ups or pulse generators as they are also known provide more accurate speed and crankshaft position signals than those equipped w ith Hall generators due to the fact that the former have fewer mechanical components which are invariably subject to some degree of play and that a crankshaft position signal is generated on each revolution of the shaft Inductive speed position pick ups are used on Renix F EZ 115K EZ t 16K and Rex l systems When working in the vicinity of the flywheel care must be taken to avoid striking the pick up with tools or dismantled compo nents The accuracy and reliability of the signal is dependent on maintaining the gap It 0 5 mm between the tip and the toothed profile for which the device is designed In addition the pick up must be mounted at right angles to the pr
105. ug 5 by the distributor 4 The timing is computed by the control unit on the basis of the following information The engine load signal is supplied by the fuel injection system IH 2 21 control unit 12 which in turn is supplied with load signals by the air mass meter A Hall generator in the distributor 4 supplies an engine speed and crankshaft position signaL Knock is indicated by the knock sensor 24 Closure of the throttle is indicated by the throttle switch 19 Any tendency of the engine to overheat is indicated by a thermostat 20 In this event the control unit advances the timing by 13 if the throttle is closed This applies only to B 230 FT variants 49 en Va ptt Ont 1 L EZ 117K Control unit connections 3 Supplies fault indication signals to test terminal 267 when test diode is connected 4 Supplies power to Hall generator in distributor 5 6 Receives supply from battery 1 across ignition switch 2 7 Grounded by throttle switch 198 when throttle is closed 8 Receives load signal from fuel system LH 2 2 control unit 217 9 Receives 12 V supply when thermostat 224 closes B 230 FT only 10 Grounds screen of lead from Hall generator in distributor 5 12 Grounds screen of lead from knock sensor 218 13 Receives signal from knock sensor 2181 15 Transmits knock controlled fuel enrichment signal to injection system control unit 217 B 230 FT only 16 Transmit
106. ugal advance Ol M IL x M ETE o Ignition timing table Vacuum advance 226 cee luu t e ee an 87 810 Timing retardation 811 Distributor overhaul C1 C28 Replacement of vacuum advance unit 1 e2 Replacement of distributor 819 823 C3 C4 Replacement of pulse generator coil 819 823 C5 C11 Replacement of distributor 828 Luuuuu eel 12 21 Replacement of pulse generator coil 828 e C22 e27 Checking air Gaps cesse ll BRL el argos C28 I ubrieGati or sull mede d LUI UE E 8 5 C29 Control unit replecement C30 Distributor testing C81 e34 Replecement of Hall generator 82001230 8280 1 1 c eiue rece ib ua Oli deii JEN 01 09 819E 823E 8290A lt ra e che daa Sedan ian eee 010 016 Wiring diagrams Feult trecing chart TSZ 4 Fault tracing Paee 81 82 86 82 83 86 83 83 84 85 86 87 97 87 87 88 89 90 92 92 94 94 95 95 96 97 98 100 100 102 03 104 79 Group 28 Ignition systems Fault tracing ys E p pde 137 S26 6 cylinder B 28 4 cylinder Group 28 Ignition systems Fault tracing TZ 28H Place distributor into a soft jaw vice Remove rotor arm Remove trigger rotor circlip 139 112 Remove trigger rotor using two round bladed screw drivers dia approx 5 mm 20 Place screwdriver tips under rotor hub and prise care fully upwards NOTE Do not press against rotor vanes or damage
107. um power as ap propriate In the rest of this discussion the term optimum timing shall be taken to mean a setting which takes account of all the factors influenced by the ignition In other words it is a compromise between the demands of high power low fuel consumption and the cleanest possible exhaust emissions The emergence of ever stricter emission standards has been the main factor in the development of ignition systems designed to optimize the combustion process under all running conditions Earlv ignition B Early ignition prevents efficient expansion of the fuel air mixture since the piston is still travelling upwards to wards TOC as the pressure rise occurs generating an abnormally high pressure accompanied by an excessive tem perature rise As a consequence of early ignition part of the unburnt fuel air mixture may ignite spontaneously causing the engine to knock In general early ignition also has an adverse effect on the exhaust emissions The Quantity of unburnt hydrocarbons HC increases while the pressure and temperature rises cause the nitrogen in the trapped air to react with the oxygen to fOfm greater quantities of nitrogen monoxide NO and nitrogen dioxide NO2 ot NO oxides of nitrogen 9 Group 28 Ignition systems Design and function General late ignition C Late ignition reduces engine power since the piston is travelling downwards from ToC when the pressure rise oc curs As a result the engi
108. unit or a separate unit assembled with it The func tion ofthe distributor e is to deliver the high tension pulse induced in the secondary winding of the ignition coil to the correct spark plug The distributor may be driven either by bevel gearing in which case it is installed vertically or directly from the camshaft horizontally installed units In systems in which the rotor arm is the only moving part such as types which employ inductive speed pick ups the liming cannot be varied by altering the position of the distributor Sensors The remaining components in the table D E comprise part of the sensor system Together with the control unit these supply information on prevailing engine running conditions Basic parameters The control unit is supplied with information on engine speed and crankshaft position D either by a Hall generator activated by a trigger rotor with four vanes mounted on the rotor shaft or by an inductive pick up mounted close to the flywheel on manuals or carrier plale automatics In this case the periphery of the flywheel carrier plate is pro vided with a series of holes whose passage is detected by the pick up and indicated in the form of electrical signals The engine load E is measured either by means of a vacuum line anached to the intake manifold or if the engine is equipped with an LH Jetronic fuel injection system i e most engines equipped with EZ K ignition systems by an air mass meter see nex
109. ves supply from battery 1 across ignition switch 2 7 Grounded by idling switch 272 when throttle is closed 9 Receives 12 V supply from AC pressure switch 81 and or idling compensation relay 293 10 Grounds Hall generator in distributor 5 11 Grounds temperature sensor 273 B 230 K only 12 Grounds knock sensor 218 terminal 2 13 Receives signals from knock sensor 218 14 Grounds fuel cut off solenoid valve 271 B230K only 16 Supplies ignition pulses to power stage 419 terminalS 20 Grounds control unit 260 24 Receives engine speed crankshaft position signal from Hall generator in distributor 5 25 Receives engine temperature signal from temperature sensor 273 Power stage connections Controls current in ignition coil 4 primary winding Grounded Grounds screen of lead connected to terminals Receives power from battery 1 across ignition switch 2 Receives ignition pulses from control unit 260 aokWNDM 54 Group 28 fgnition systems Design and function System descriptions 147 115 ein EZ 115K EZ 115K B280EIF The control unit 1 computes the optimum timing on the basis of information from the various sensors and delivers an ignition pulse at exactly the correct instant to the power stage 26 which responds by making and breaking the current in the primary winding ofthe ignition coil 25 The high tension current induced in the secondary winding
110. w the throttle 2 is only panially open and the vacuum in the manifold is high lapprox 60 kPa As the engine load increases the throttle opens further and the vacuum in the manifold gradually falls The ignition system may receive and process the load signal from the intake manifold by one of three basic methods in order to adjust compute the timing setting Vacuum advance unit A On the TZ 28H system the vacuum line is connected to a vacuum advance unit 3 on the distributor The unit houses a diaphragm one side of which is open to the vacuum in the manifold and the other to atmosphere As the vacuum increases at low engine load with a partially open throttle the distributor plate is rotated to advance the timing Electrical vacuum converter B The vacuum line on the Renix F system is connected to a vacuum con erter integral with the control unit Al though each vacuum converter is designed specifically for a particular system the principle of operation is the same in all cases The vacuum is applied to one side of a spring loaded diaphragm 4 the other side of which car ries an iron core 5 moving inside a coil 6 The coil is connected to an oscillator circuit in the control unit the fre quency in which varies with the position of the core and as a result is proportional to engine load Electronic pressure switch C On the EZ 1 18K system the vacuum line IS connected to a pressure switch 7 inside the control unit The
111. wer slage 10 interrupl Ihe spark 10 every second plug The speed limiting function normally inlervenes at aboul 6200 r min In the case of cars equipped with Fengines the speed limiting function controlled by Ihe ignition syslem control unil is set to op erate 81 a higher level than thal controlled by its fuel system counlerpart This prevents unburnl fuel from reaching Ihe catalytic converter with the anendant risk of overheating The control unit memory is programmed with a range of speed and load values The unit improves the accuracy of control by in terpolating between Ihese values performing up to about 10000 computations per minute to ensure that optimum liming is maintained under all conditions As many as 4000 individual settings may be computed as required Built from components such as integrated circuits transistors diodes and capacitors electronic components like the control unit are relatively fragile Since the electronics used in cars are exposed to such a diversity of operating conditions they are subject to particularly arduous demands The equipment mUSI be designed to withstand vibrations moisture wide temperature fluctu ations variable voltages and other sources of outside interference e g from radios to which the electrical system is unavoidably exposed In the case of certain internal faults the control unit regulates the ignition in accordance with a fixed pre programmed timing curve In Ihe absence of a
112. wer stage 86 Rev counter 156 Radiator fan motor 200 AC compressor solenoid 202 Climate control 218 Knock sensor Connector RH A post Connector LH A post Connector at LH wheel housing Ground terminal on intake manifold Connector at LH wheel housing moowp Engine running EZ 116K Ignition system B234F B204 E Az x CE ox Ib EZ 116K Ignition system B234F B204E Battery Ignition switch Ignition coil Distributor Spark plugs 11 Fusebox 29 Positive terminal board Ouve D 84 Temperalure sensor 198 Throttle switch 218 Knock sensor 260 Control unit 413 Pulse generator 419 Power stage 472 Fuel system control unit 482 Diagnostic unit cr ommoou Connector RH A post Connector LH A post Connector at LH wheel housing Ground terminal on intake m nifold Connector at bulkhead Connector at LH wheel housing Connector at RH wheel housing Connector at LH wheel housing Group 28 Ignition systems Fault tracing Rex 1 N Fault tracing Rex l with self diagnostics B230F engine Federal USA The Rex l ignition system features self diagnostics the functions of which are incorporated in the control unit NOTE AII fault codes will be erased if the busbar 30 supply is disconnected The system features three different control functions Checking NI Start and run engine up to working temperature tf engine does not start Check that fuse No 1 is intact If engine st
113. wer stage When this signal goes high 5 VI the power stage permits the igni tion coil to charge When the signal again falls to 0 VI the power stage interrupts the current in the ignition coil pri mary and the stored energy is released in the form of a high tension pulse in the secondary Constant charge In the EZ K and TZ 28H systems the power stage incorporates a circuit which continuously monitors the primary current used to charge the ignition coil and ensures that the charging current remains constant regardless of engine speed or battery voltage This feature is designed to ensure that the ignition coil 2 receives a constant charge at all times irrespective of these parameters As a result the charge in the coil is always a maximum and the ignition volt age remains constantly high Standing current protection To avoid overheating of the ignition coil if the ignition is switched on with the engine at rest the control unit in corporates a circuit which operates the standing current protection function via the power stage Since the control unit no longer receives signals from the Hall generator or speed pick up whichever is applicablel when the engine has been stopped it commands the power stage to interrupt the current in the primary winding of the coil Power stage cooling Since operation of the power stage generates heat the unit is mounted on a heat sink attached to the body Secure contact between the unit and heat sink
114. witch illustrated The switch is mounted on the throttle spindle 3J which actuates a cam plate 5 and an arm 6 The arm operates a microswitch 7 which closes to ground a terminal in the connector 8 Apart from supplying a signal to the control unit when the throttle is closed the type of switch used on some en gine variants incorporates a set of full load contacts 9 which close when the throttle is fully open In this case a full load signal is fed to the fuel system control unit instructing it to extend the injector opening period However this feature is not used on turbocharged engines C The EZ 118K system employs an idling switch 12 mounted on the throttle cable pulley to indicate when the throttle is fully closed The control units use the signal to establish a comfortable timing setting when idling and to activate the fuel cut off function under engine braking conditions The EZ 118K control unit also uses the signal as a condition for advancing the timing for idling speed compensation when a drive position is selected on an automatic model or the AC compressor is switched in t is extremely imponant that the throttle switCh be correctly adjusted before checking the timing to ensure that the idling setting is correctly measured Electronic ignition systems not equipped with a throttle switch or idling air control switch are supplied with information on idling conditions in the form of a signal representing the vacuum
115. y transmitted to the piezoelectric crystal making the unit less sensitive to the effect of the tightening torque Type 0 is used on the EZ 115K system on the B280 engine which is fitted with a knock sensor for each bank of cylinders The only difference between this variant and type C is that the connection lead is integral with the unit Type IC and D sensors are less sensitive to tightening torque than earlier types The design permits the torque to vary from 15 to 25 Nm 1 1 18 ft lb without any adverse effect on the performance of Ihe device Although production of type B was discon tinued in 1986 it is fully interchangeable wilh type C Particular care muSI be taken when fining the older type 01 sensor a torque wrench must be used to lighten Ihe device in position Since the ignition may be retarded in each individual cylinder in the evenl of knock the tlming In each may vary by as much as ap prox 0 15 Apart from the fact that knock control is inherently a major advantage the facility of eliminating it in an individual cylinder means Ihat fuel utilization can be maximized in relation to the knock Ihreshold in each ThIS is importanl since conditions in the various cylinders may differ somewhat in terms of combustion temperature fuel residue deposits on cylinder walls in jector design and so on Relardation of the ignition in each individual cylinder is a feature of all systems equipped with knock sensors dealt with in thi

700 Section 2 (28) Ignition systems

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