WORKSHOP MANUAL Porsche K-Jetronic - members
Contents
1. THERMO TIME SWITCH CHART Resistance in ohms from terminal from terminal from terminal Design Number Temperature Gto Ground WtoGround GtoW 45 C 9 5s below 104 F 30 40 0 30 40 above 122 F 55 85 120 160 55 85 35 8 below 86 F 25 40 25 40 above 104 F 50 80 50 80 18 C 8 s below 55 50 70 50 70 above 73 50 70 50 70 15 8 below 50 F 50 70 infinite above 68 F 50 70 infinite infinite Cold Start Valve Disconnect the electric plug from the cold start valve Remove the cold start valve from the intake manifold Hold the cold start valve in a graduate A rubber hose may be required to reach the graduate Temporarily connect one start valve terminal to ground and the other terminal to the terminal of the ignition coil Bridge the electric safety circuit see Electric Wiring Diagram Turn the ignition on for not more than 30 seconds If the cold start valve does not spray replace the cold start valve Caution Keep the cold start valve and connecting wires away from the battery terminal to prevent sparking Turn the ignition off and disconnect the temporary electrical wires from the cold start valve Wipe the cold start valve dry With the electric safety circuit still bridged switch the ignition on for one minute If the cold start valve drips or leaks replace the cold start valve 18 ROBERT BOSCH Porsche K Jetronic WARM UP REGULATOR2. 36 ROBERT BOSCH Porsche K Jetronic ELECTRIC WIRING DIAGRAM 1 Relay 2 Throttle Valve Switch 3 Start 4 Warm up Regulator 5 Electric Fuel Pump 6 Thermo time Switch 911 911 1974 75 27 911 1973 2 41 Bridging the electric safety circuit Remove the relay from the mounting bracket Bridge the circuit with a fused 8 amp jumper between terminals 30 51 and 87 see Component Location NOTE The fuel pump relay and warm up regulator relay are not mounted in the same place on all vehicles Be sure to remove the fuel pump relay to bridge the safety circuit 1 Electric Fuel Pump 2 Warm up Regulator 3 Thermovaive iliary Air Valve nition Distributor hermo time Switch L Air Flow Sensor Switch D Electronic Relay 911 911S 911SC since 1976 5 7 Bridging the electric safety circuit The electric safety circuit be bridged by disconnecting the air flow sensor plug or by bridging terminals 30 and 87a with a fused 8 amp jumper wire K Jetronic Porsche ROBERT BOSCH 37 gd ELECTRIC WIRING DIAGRAM 924 1 Electronic Relay 2 Start Valve 3 Thermo time Switch 4 Electric Fuel Pump 5 Warm up Regulator 6 Auxiliary Air Device 7 Air Flow Sensor Contact 928 oa iz ww Central Electrics Base Assembly ump Relay No XVII Pumps Warm up Regulator Auxiliary Air
3. Valve needle 7 Seal ring Screw plug Screw plug 14 Flat seal ring 1 2 3 4 5 6 7 8 10 11 12 13 from fuel distributor b from warm up regulator 5 4 7 8 12 4 fuel return SYSTEM PRESSURE REGULATOR with push valve WARM UP REGULATOR REPAIR 911 Removal Remove intake hose 1 from the auxiliary fan housing Loosen hose clamps 2 and 3 and remove the hoses from the auxiliary fan housing Note 911SC models require removal of a plastic rivet in each hose Loosening screw 4 and tilting the fan motor upwards will make the hose removal easier Installation Replace the warm up regulator as re quired and reassemble in the reverse order K Jetronic Porsche ROBERT BOSCH 35 INJECTOR REMOVAL 928 The injectors are held in place by a rubber bushing mounted in a threaded sleeve To remove the threaded sleeve turn the fixed hex part of the injector as shown THROTTLE ACTIVATED VALVE Removal Remove the venturi assembly from the intake manifold Remove the throttle activated valve from the throttle shaft Installation Install the new throttle activated valve on the throttle shaft Replace the venturi assembly on the intake manifold Adjust the warm control pressure idle value see Warm Up Regulator with Full Load Enrichment Warm Control Pressure WITH Throttle Activated Valve Tighten both fastening screws
4. 30 40 AMBIENT TEMPERATURE 0 438 140 053 WARM CONTROL PRESSURE 0 438 140 053 Without vacuum With 390 450 mm Hg vacuum applied 0 438 140 063 Without vacuum With 340 420 mm Hg vacuum applied SYSTEM PRESSURE Checking Value 5 2 5 8 bar Setting Value 5 3 5 5 bar LEAKAGE TEST Minimum pressure after 10 minutes 1 7 bar Minimum pressure after 20 minutes 1 5 bar 3 8 ei c z 8 o 10 20 30 40 AMBIENT TEMPERATURE 0 438 140 063 2 8 3 2 bar 3 4 3 8 bar 2 8 3 2 bar 3 4 3 8 bar INJECTION VALVE OPENING PRESSURE 3 0 4 1 bar Idle speed CO specifications are given on the emissions decal in the vehicle engine compartment K Jetronic Porsche ROBERT BOSCH 45 mmm ROBERT BOSCH SALES CORPORATION ROBERT BOSCH Member of the Bosch Group 2800 South 25th Avenue Broadview Illinois 60153 Telephone 312 865 5200 JETRONIC SERVICE MANUAL 1979 Supplement K Jetronie This packet contains the main title page equipment lists and warranty information for the K volume of your Jetronie Service Manual Use the main eontents page on the back of the main title page to correctly place all information in the manual When a new page replaces an old page the new page will have a revision date 12 79 at the bottom of the page Always keep the page with the latest revision The older page should be discar
5. 0 6 Nm 3 5 5 3 in Ibs Be careful not to overtighten the check valve and damage the deli cate plastic threads Caution On 1976 and later Porsche 911 models the fastening screws which secure the protective plate also fasten part of the front axle support and stabilizer bar Be sure to tighten the protective plate socket head screws to 47 Nm 35 ft Ibs and the protective plate self locking nuts to 28 Nm 21 ft Ibs Self locking nuts which have been reused several times should be replaced with new ones 34 ROBERT BOSCH Porsche K Jetronic PRESSURE REGULATOR REPAIR Clean the fuel distributor especially around the sys tem pressure regulator Remove the screw plug large screw plug and push valve if fitted shim spring and screw plug f needle valve Replace the O ring behind the control 2 bank piston Be careful not to damage the needle valve fuel distributor spring Control piston during removal and assembly Install the control piston spring shim push valve if fitted and the screw plug using a new gasket Tighten the screw plug to 13 15 Nm 10 11 ft Ibs Check the system pressure and adjust as necessary The needle valve and large screw plug on push valve type distributors are only replaced together as a unit SYSTEM PRESSURE REGULATOR without push valve Fuel distributor housing www Spring Retainer 1 2 3 6 10 29 13 Retaining ring 7 Spring hims
6. 030 007 023 030 320i 320i models use Vacuum Limiter 0280 160305 CAL 0280 162 102 HA Electro Air Valve 0 280 160 402 Fuel Pump Relay 0 332 204 401 CAL California models HA High Altitude 12 79 4 ROBERT BOSCH K Jetronic KJetronic Equipment BMW wissen TIME CCUMULATOR REGULATOR AIR VALVE VALVE SWITCH 0438170 0438140 0280140 0280170 0280130 007 014 104 405 214 982 007 014 104 405 214 982 007 014 104 405 214 982 007 014 0280 160 402 405 214 982 007 014 0280 160 402 405 214 982 007 014 0280 160402 405 214 12 79 K Jetronic ROBERT BOSCH 5 el MERCEDES BENZ KJetronic Equipment MIXTURE AIR CONTROL FUEL FLOW INJECTION YEAR UNIT DISTRIBUTOR SENSOR VALVE 0 438 040 0438 100 0438 120 0437 502 011 1977 0438060014 032 280 SE CE 1978 0438 060 014 011 032 010 1979 0438 060014 011 032 010 450 SL SLC 1977 003 012 062 010 450 SEL SE All models use diaphram damper 0 280 161 007 CAL California models HA High Altitude 12 79 6 ROBERT BOSCH K Jetronic n M M MM KJetronic Equipment MERCEDES BENZ 45 ae Eg PUMP FILTER ACCUMULATOR REGULATOR AIR VALVE VALVE SWITCH 0580 254 0450905 0438 170 0 438 140 0280 140 0280
7. 110 260 1978 0332015001 0 332 015 009 and 0 332 204 110 12 79 K Jetronic ROBERT BOSCH 15 ummm
8. 7 3 1 bar With engine vacuum at idle 2 7 3 1 bar With engine vacuum at 1800 RPM 3 4 3 8 bar 1977 model Without vacuum 2 7 3 1 bar With engine vacuum at idle 3 4 3 8 bar SYSTEM PRESSURE Checking Value 4 5 5 2 bar Setting Value 4 7 4 9 bar f LEAKAGE TEST Minimum pressure after 10 minutes 1 7 bar Minimum pressure after 20 minutes 1 5 bar INJECTION VALVE OPENING PRESSURE 2 5 3 6 bar Idle speed and CO specifications are given the emissions decal in the vehicle engine compartment K Jetronic Porsche ROBERT BOSCH 43 TEST SHEET 911 SC FUEL PUMP min 1000 cc in 30 seconds COLD CONTROL PRESSURE bar 3 0 25 i a 15 o 1 0 0 5 o 10 20 30 40 AMBIENT TEMPERATURE 0 438 140 045 WARM CONTROL PRESSURE Without vacuum 2 7 3 1 bar With engine idle vacuum 3 2 3 6 bar SYSTEM PRESSURE Checking Value 4 5 5 2 bar Setting Value 4 7 4 9 bar LEAKAGE TEST Minimum pressure after 10 minutes 1 7 bar Minimum pressure after 20 minutes 1 5 bar INJECTION VALVE OPENING PRESSURE 2 5 3 6 bar Idle speed and CO specifications are given on the emissions decal in the vehicle engine compartment 44 ROBERT BOSCH Porsche K Jetronic RL EOS TEST SHEET 928 FUEL PUMP min 1360 cc in 30 seconds COLD CONTROL PRESSURE bar c 2 a E o 2 8 o 10 20
9. CONTROL PRESSURE Porsche uses several warm up regulators on its vehi cles The testing procedure and test specifications are different for each type of warm up regulator Find the warm up regulator type to be tested from the ones listed below and proceed with the test instructions for that specific type Standard Warm Up Regulator Connect pressure tes ter KDEP 1034 see Mounting Pressure Tester Use the test specification for the specific warm up reg ulator Cold Control Pressure The engine must be cold not run for several hours preferably overnight Discon nect the plug from the warm up regulator Open both valve screws on the three way valve of the pressure tester Bridge the safety circuit see Electric Wiring Diagram Switch the ignition on to run the electric fuel pump and read the cold control pressure on the gauge The pressure must be within the tolerance band given on to pressure gauge the appropriate test specification graph Turn the ignition off Warm Contro Pressure Engine temperature is not important Attach the plug to the warm up regulator Bridge the safety circuit Open both valve screws on the pressure tester as shown Switch the ignition on to operate the electric fuel pump When the pressure stops increasing read warm control pressure on the gauge The warm control pressure must be within the tolerance given on the test sheet Turn the ignition off to warm up regulator from
10. FLOW INJECTION YEAR UNIT DISTRIBUTOR SENSOR VALVE 0438 040 0 438 100 0438 120 0 437 502 142 144 145 242 244 245 242 244 245 CAL 1976 0 438 060 008 006 016 005 1977 0 438 060 008 006 016 005 262 264 265 om 1978 0498060019 088 CAL 056 CAL 005 1979 0438 060 019 033 056 013 kit 2 437 001 001 is required to install new fuel distributor 0 438 100 005 in 1974 Volvo LAMBDA COMPONENTS LambdaSensor Frequency Valve Control Unit 0258001 0280150 0280800 240 Series 1977 CAL 001 300 001 1978 CAL 004 300 001 1979 004 300 260 Series 1978CAL 005 300 003 1979 005 300 005 High Altitude Automatic Transmission CAL California Models 12 79 14 ROBERT BOSCH K Jetronic KJetronic Equipment VOLVO 996 001 001 004 100 100 996 006 001 014 106 404 996 010 001 014 106 404 996 010 007 Pe 100 404 996 010 007 004 100 404 E 996 021 007 004 Man 404 996 010 007 004 100 404 996 010 007 004 100 404 996 021 007 004 aan 404 996 010 001 018 202 400 996 010 007 021 HA 202 400 996 010 014 021 CAL 202 400 996 021 021 004 202 400 FUEL PUMP RELAY 240 1975 1976 1977 0332204125 1978 0332015 009 and 0 332 204 110 240CAL 1976 1977 0 332 204 5 1978 0332 015 001 0 332015 009 and 0 332 204 110 260 1976 1977 0 332 204 125 1978 0332015 009 and 0 332 204
11. Plunger Movement Engine temperature must be above 20 C 68 F Remove the air filter from the air flow sensor Bridge the electric safety circuit see Electric Wiring Diagram Switch the ignition on for 10 seconds to apply control pressure to the plunger Fully push the sensor plate down by hand to its maximum deflection as shown Even resistance must be felt over the entire lever movement If not theair flow sensor plate is not moving freely see below Now pull the sensor plate up rapidly almost back to its rest position The plunger will not follow the rapidly moving sensor plate but the shock of the plunger hitting the sensor plate lever when it does come down must be felt If this cannot be felt the plunger is not moving freely see below Fully push the air flow sensor plate down to its maximum deflection When released the sensor plate must fall back to its rest position after bouncing once or twice on the spring stop If not the air flow sensor plate is not moving freely see below If the air flow sensor plate does not move freely loosen the mounting screws around the air flow sensor housing to check if housing warpage is caus ing the lever to bind If necessary replace the gasket under the air flow sensor and uniformly tighten the fastening screws If the plunger does not move freely remove the fuel distributor from the air flow sensor see Fue Dis tributor Repair Remove the plunger from the fuel
12. distributor If it is necessary to blow compressed air in the control pressure connection hole to free the plunger hold the plunger with your hand as shown to prevent the plunger from falling out of the fuel dis tributor Clean the plunger with an appropriate solvent If the plunger still binds in its barrel replace the fuel distributor 14 ROBERT BOSCH Porsche K Jetronic _ _ _ gt 2 68 2 Air Flow Sensor Plate Position Remove the air filter from the air flow sensor The sensor plate must be flat The chamfered edge of the sensor plate must face down The word top or five punch marks are stamped on the top of the sensor plate The sensor plate must pass through the narrowest part of the funnel without touching the sides If the sensor plate touches the sides of the funnel loosen the sensor plate fastening screw Insert the appropri ate guide ring see 700 List Hold the fastening screw as shown to prevent the sensor plate from moving down When the guide ring is in place tighten the fastening screw to 5 0 5 5 Nm 3 7 4 0 ft Ibs Then loosen the screw and retorque to the same value The air flow sensor plate must not now be able to be turned by hand Bridge the electric safety circuit see Electric Wiring Diagram Switch the igniti
13. screws attach both pressure lines to connection 1 of the tester valve Screw connector piece KDEP 1034 10 2 into the con trol outlet hole of the fuel distributor Attach connec tion 3 of the tester valve to the connection piece in the fuel distributor Attach connection 2 to the pressure gauge with the other connecting hose Bleed the tester as indicated below For 911 models without throttle activated valve Clean the fuel fittings on the control pressure line at the fuel distributor Unscrew the control pressure line from the fuel distributor Using adapter KDEP 1034 10 3 attach the control pressure line to connection 3 of the valve tester Unscrew the fitting left in the control pressure outlet of the fuel distributor and install connecting piece KDEP 1034 10 2 in its place Using a connecting hose attach connection 1 of the tester valve to the connect ing piece in the fuel distributor Attach connection 2 to the pressure gauge with the other connecting hose Bleed the tester as indicated below 30 ROBERT BOSCH Porsche K Jetronic For 924 models Clean the fuel fittings for the control pressure line on the fuel distributor Unscrew the control pressure line from the fuel distributor and attach the line to connection 1 on the tester valve as shown Attach connection 3 of the tester valve to the fuel distributor with the connecting hose Attach con nection 3 of the tester valve to the fuel distributor with the con
14. technical instruction booklet Fue Injection Con tinuous Injection System CIS at the back of the manual describes the components and operation of the K Jetronic fuel injection system in detail A thorough understanding of the various compo nents is required before working on K Jetronic fuel systems Before trouble shooting testing or adjusting the K Jetronic fuel injection system the ignition sys tem and the mechanical system of the engine compression valve timing etc must be within specification and operating properly Verify that these systems are in proper working order before proceeding further K Jetronic fuel systems have an electric safety circuit which prevents the electric fuel pump and other electrical devices from operating unless the engine is running or being started The electric safety circuit can be bridged to apply voltage to any electrical component without running or starting the engine This procedure can be found in the Electric Wiring Diagram section of the manual In addition 911SC models use a thermo valve which enriches the fuel mixture during starting by blocking the warm up regulator vacuum which de creases control pressure After starting the valve opens by means of an electric heating element Several component tests Auxiliary Air Valve and Warm up Regulator require that the engine is cold For cold tests the engine must not have been run for several hours preferably overnight Most v
15. up Regulator Incorrect system pressure see System Pressure Fuel system pressure leakage see Fue Leaks Injection valve s leaking opening pressure too low see Testing Injectors Unequal fuel delivery between cylinders see Comparative Test Basic idle and or CO adjustment incorrect see d e and CO Adjustment Throttle plate does not open completely 10 ROBERT BOSCH Porsche K Jetronic VACUUM LEAKS There must be no air leaks in the air intake system Any air drawn into the engine without passing 4 through the air flow sensor will cause a lean air fuel mixture condition and improper engine operation To test for air leaks remove the outlet hose from the auxiliary air valve and pressurize the hose with com pressed air Hold the throttle plate open and coat all air fittings arrows below with soapy water Bubbles indicate a leak Replace any defective hoses gaskets or seals K Jetronic Porsche ROBERT BOSCH 11 AIR FLOW SENSOR updraft only Sensor Plate Plunger Movement Engine temperature must be above 20 C 68 F Remove the rubber boot from the air flow sensor Bridge the electric safety circuit see Electric Wiring Diagram Switch the igni tion on for 10 seconds to apply control pressure to the plunger Fully lift the sensor plate up by hand to its maximum deflection as shown Even resistance must be felt over the en
16. 01 217 994 005 001 020 107 401 217 978 021 014 020 107 401 217 985 021 010 020 107 401 217 994 005 001 032 107 401 217 978 021 014 032 107 401 217 978 021 010 032 107 401 217 978 021 014 051 107 401 217 978 021 010 020 107 401 217 978 021 010 032 107 401 217 978 021 010 051 107 401 217 LAMBDA COMPONENTS Lambda Sensor Frequency Valve Control Unit 0258001 0280150 0280800 99 1977 001 300 002 1978 001 300 002 1979 012 300 002 99Turbo 1978 001 300 004 900CAL 1979 012 300 002 900 Turbo 1979 012 300 004 12 79 K Jetronic ROBERT BOSCH 11 TTT VOLKSWAGEN K Jetronic Ey ROON DISTRIBUTOR SENSOR 0 502 1976 006 007 008 007 1977 020 021 033 007 Dasher 1978 052 043 CAL 088 CAL 015 061 054 Rabbit Scirocco 1978 020 021 033 015 All Dasher models with manual transmission use vacuum limiter 0 280 160 116 Rabbit and Scirocco models with manual transmission use vacuum limiter 0 280 160 122 or 0 280 162 106 HA 12 79 12 ROBERT BOSCH K Jetronic KJetronic Equipment VOLKSWAGEN 992 003 001 107 401 214 980 003 007 Be 107 402 214 980 025 019 011 107 402 214 980 025 019 011 107 402 214 980 014 007 011 107 402 214 980 021 019 Ge 107 402 214 980 021 019 011 107 402 214 12 79 K Jetronic ROBERT BOSCH 13 Ne VOLVO KJetronic Equipment us ESTEE CONTROL FUEL
17. 170 0280 130 984 004 004 nene OSEE 403 975 004 004 Sie 037 403 027 975 004 004 031 CAL 037 403 041 HA 984 004 004 015 032 403 2 975 004 004 Sie 032 403 975 004 004 049 HA 032 403 975 004 004 061 032 403 E 984 004 004 010 032 403 975 004 004 dires 032 403 975 004 004 060 032 403 12 79 K Jetronic ROBERT BOSCH 7 EEE PORSCHE Equipment MIXTURE AIR CONTROL FUEL FLOW INJECTION MODEL YEAR UNIT DISTRIBUTOR SENSOR VALVE 0 438 040 0 438 100 0 438 120 0437 502 911T 1973 001 017 002 002 1974 003 017 004 004 911 1975 005 006 004 004 911S 1976 005 006 004 004 1977 005 006 004 004 1978 018 031 070 004 911 SC 1979 018 031 070 004 1976 011 016 024 009 1977 011 016 024 009 Turbo 1978 022 037 085 009 1979 022 037 085 009 1976 0438 040 012 005 022 013 1977 0438 040 047 039 066 013 924 1978 0438 040 047 039 066 013 1979 0438 040 063 005 103 013 1978 0438 080 004 027 049 012 928 lt 1979 0438 080 009 027 107 012 AC HT 1973 Throttle Valve 0438 160 001 911SC 19770n Vacuum Limiter 0280 160 111 1 from 9 77 thru Vacuum Limiter 0280 160 102 Electro Air Valve 0280 160 400 2 from 3 78 thru ane 911 1974 Throttle 0438 160 001 1974 77 Vacuum Limiter 0280 160 111 12 79 8 ROBERT BOSCH K Jetronic KJetronic Equipment PORSCHE C 998 0450 903 007 015 008 02
18. 5 998 007 015 008 102 991 033 015 009 402 985 003 015 017 200 402 985 016 009 033 206 402 984 021 009 045 209 409 984 021 009 045 209 409 990 009 005 022 205 401 990 009 005 022 205 401 dud 009 005 054 212 400 009 005 054 214 400 976 003 015 011 100 401 214 976 021 015 011 100 401 223 976 021 015 011 100 401 223 984 021 024 011 100 401 223 984 and 019 ae 211 402 214 984 and 025 063 211 402 214 SE tree SE SS 1979 Solenoid Valve 0280 170 500 12 79 K Jetronic ROBERT BOSCH 9 22 SAAB KJetronic Equipment MIXTURE AIR CONTROL FUEL FLOW INJECTION YEAR UNIT DISTRIBUTOR SENSOR VALVE 0438 040 0438100 0438120 0437 502 007 005 009 004 1975 1976 007 005 009 004 99 GL GLE 99 EMS 1977 007 005 A 004 1978 049 023 071 004 1979 049 023 071 004 1977 028 018 050 004 99 GL GLE 99 EMS 1978 051 032 073 004 CAL 1979 051 032 073 004 1978 051 032 073 004 99 Turbo 1979 049 023 071 004 900 900 1979 051 032 073 004 CAL 1979 051 032 073 004 900 Turbo 1976 and 1977 99 Series use fuel pump relay 0 332 204 125 CAL models 12 79 10 ROBERT BOSCH K Jetronic E LL Un M KJetronic Equipment SAAB Au befier avin OANE 005 001 013 107 401 214 994 005 001 013 107 4
19. 976 005 005 007 008 008 100 005 007 1978 0438 050 001 024 040 015 1979 0438 050 001 060 040 015 1979 0438 050 005 062 052 015 Fox models use vacuum limiter 0 280 160 116 MT or 0 280 162 104 HA MT 5000 models use vacuum limiter 0 280 160 126 MT MT Manual Transmission AT Automatic Transmission HA High Altitude CAL California models 12 79 2 ROBERT BOSCH K Jetronic KJetronic Equipment AUDI d THERMO L FUEL WARM UP AUXILIARY COLD START CCUMULATOR REGULATOR AIRVALVE is 0438140 0280140 o280170 0290130 992 011 007 011 100 ED 992 011 007 011 100 406 214 980 011 007 011 100 406 214 992 003 007 011 107 401 214 992 003 007 011 107 401 214 980 003 007 011 107 402 214 980 025 019 ew 107 402 214 980 025 019 011 107 402 214 980 025 019 Sew 107 402 214 980 028 019 048 107 402 214 980 025 019 034 104 400 214 970 025 019 034 104 400 214 970 028 019 048 400 214 LAMBDA COMPONENTS Lambda Sensor Valve Control Unit 0258001 0280150 0280800 FoxCAL 1979 013 300 011 5000 CAL 1979 013 300 007 009 MT 12 79 K Jetronic ROBERT BOSCH 3 Je BMW KJetronic Equipment MIXTURE AIR CONTROL FUEL FLOW INJECTION MODEL YEAR UNIT DISTRIBUTOR SENSOR VALVE 0438 040 0 438 100 0 438 120 0 437 502 023 030 1977 1978 019 023
20. Device Starting Motor Alternator Thermo time Switch tors for Ignition Transformer o N Ignition Distributor Ignition Transformer 4 D Si Fuse ei wie 06 Plug connections at central electrics base assembly 07 0 T5 pin plug in engine compartment Bridging the electric safety circuit Remove relay No XVII located in the lower part of the passenger compartment see Component Location 38 ROBERT BOSCH Porsche K Jetronic SERVICE PARTS LIST Porsche Illustration Number Description Bosch Part No 1 Fillister Head Screw 911 2910 022 174 924 2910 022 172 Washer 2916 710 649 Shim 1 mm 2430 000 090 5mm 2430 000 094 Spring 2434 611 030 O ring 2430 210 003 Seal 911 2430 210 013 924 2430210036 K Jetronic Porsche ROBERT BOSCH 39 TEST SHEET 924 FUEL PUMP min 750 cc in 30 seconds COLD CONTROL PRESSURE CONTROL PRESSURE 20 30 40 AMBIENT TEMPERATURE 0 438 140 011 WARM CONTROL PRESSURE 3 4 3 8 bar SYSTEM PRESSURE Checking Value 4 5 5 2 bar Setting Value 4 7 4 9 bar LEAKAGE TEST Minimum pressure after 10 minutes 1 7 bar Minimum pressure after 20 minutes 1 5 bar INJECTION VALVE OPENING PRESSURE 2 5 3 6 bar Idle speed and CO specifications are given the emissions decal in the vehicle engine compartment 40 ROBERT BOSCH Porsche K Je
21. ERY CHART Cylinders Setting Point Delivery comin 4 5 6 8 120 0 120 0 131 0 140 0 140 0 153 0 160 0 160 0 175 0 Test Results Any injector which does not fall within the specified value should be switched with an injec tor from another cylinder which does fall within the specified value the suspected injector is now within specification replace the fuel distributor If the suspected injector is still not within the specified tolerance replace the injector K Jetronic Porsche ROBERT BOSCH 25 eg Idle screw t Jd IDLE SPEED AND CO ADJUSTMENT 911 with throttle activated valve Preparation Pressure tester KDEP 1034 must be re moved from the vehicle The electric safety circuit must NOT be bridged The engine must be warm If any fuel lines have been opened warm the engine under load to purge the lines of air Idle speed and CO specifications are given on the emissions decal in the vehicle engine compartment Vehicles with Secondary Air Pump Remove and plug the pressure hose on the air pump Vehicles with Vacuum Limiter Remove and plug the air hose which connects with the T connection above the throttle plate Idle Speed Adjustment Turn the idle bypass screw arrow to adjust idle speed CO Adjustment Make the CO adjustment im mediately after a test drive engine at operating tem perature Install the CO sensor in the tailpipe Re move the se
22. K Jetronic COMPONENT LOCATION 911T 911 911S through model 1975 Mixture Control Unit 1 Injectors 2 The Start Valve located on back Fuel Accumulator 1 Fuel Filter 2 of intake manifold below the venturi assembly The Thermo time Switch is located on engine block below the secondary air pump Bridging Electric Safety Circuit Electric Fuel Pump Secondary Air Pump Pressure Hose arrow K Jetronic Porsche ROBERT BOSCH 5 COMPONENT LOCATION 911 911 911SC beginning model 1976 Mixture Control Unit with Air Filter Removed 1 Throttle Valve sembly 2 Intake Housing 3 Secondary Air Pump 4 Secondary Air Pump Pressure Hose arrow Fuel Pump Protective Cover above Fuel Pump Fuel Pump Test Point arrow CO Test Point for Vehicles with Catalytic Con below verter 6 ROBERT BOSCH Porsche K Jetronic LOCATION 924 1 Start Valve hidden 2 Warm up Regulator 3 Auxiliary Air Valve 4 Injectors 5 Fuel Filter 6 Mixture Control Unit Thermo time Switch arrow as viewed from Fuel Accumulators 1 Fuel Pump 2 Noise underneath engine Dampers 3 since 1977 arrow Fuel Pump and Fuel Accumulator 1976 model Fuel Pump Test Point arrow Secondary Air Pump Pressure Hose arrow K Jetronic Porsche ROBERT BOSCH 7 COMPONENT LOCATION 928 Start Valve 1 Auxiliary Air Valve 2 Thermo time Switch Injecto
23. WORKSHOP MANUAL Porsche K Jetronic ROBERT BOSCH CONTENTS Introduction ee eser NNN NENNEN EEN NEEN NEEN 3 Test Equipment 4 Component Location 5 Vacuum Diagram 9 Trouble Shooting Chart 10 00 11 Component Tests Air Flow Sensor 12 Auxiliary Air Valve 16 Mer 17 Cold Start 18 Warm Up Regulator 19 System Pressure 22 Leakage Test 23 Testing 23 Tost 24 Idle Speed CO Adjustment 26 Mounting Pressure 30 Component Repair Fuel Distributor Repair 911 914 32 Fuel Distributor Repair 928 33 Fuel Pump Repair 34 Pressure Regulator Repair 35 Warm up Regulator Repair 911 35 Injector Removal 928 36 Throttle Activated Valve 36 Electric Wiring Diagram 37 Parts kist p POTEO EEA E AE 39 Test Sheet een deg IILAMPER Gu ep NER 40 A 2 ROBERT BOSCH Porsche K Jetronic INTRODUCTION Testing Procedures The construction and opera tion of the K Jetronic CIS fuel injection system is different from other fuel injection systems The
24. aling plug from the air flow sensor hous ing Using wrench KDEP 1035 turn the CO mixture screw out counterclockwise to a value leaner than specification Then turn the mixture screw in clockwise to bring the CO value into specification Always adjust from the lean side when setting CO After each adjustment remove the wrench and accel erate the engine to stabilize the mixture Acce erating the engine with the wrench in place could bend the air flow sensor lever When the CO adjustment is correct reconnect the pressure hose to the secondary air pump The CO value must now be less than 196 If not clean the air filter on the secondary air pump with compressed air Install the plug in the air flow sensor housing and install the vacuum limiter air hose if fitted Testing Throttle Activated Valve The 1973 74 911S uses a throttle activated valve to energize the start valve Test the valve by attaching an ohmmeter to the two electrical connections on the throttle activated valve In the idle position the ohmmeter must read infinity circuit open When the hand throttle between the seats is pulled all the way out the ohmmeter must read zero resistance circuit closed If not adjust the throttle activated valve Adjusting Throttle Activated Valve Insert a 2 mm thick feeler gauge between the idle stop screw and the stop boss Holding the stop screw against the feeler gauge turn the stop screw until the throttle circuit just clos
25. an appropriate fitting M 14 x 1 5 to the outlet on the fuel distributor Hold the line coming from the fuel distributor in a 1500 cc or larger graduate Inflexible metal fuel lines may require a rubber hose to reach the graduate Remove the electric plug from the warm up regulator and the auxiliary air valve Bridge the electric safety circuit see Electric Wiring Diagram Turn the ignition on for the amount of time specified Point for Fue Pump on the test sheet If fuel quantity is not within specification check for sufficient voltage supply to the fuel pump minimum 11 5 volts or a dirty fuel filter If all the above are satisfactory replace the electric fuel pump K Jetronic Porsche ROBERT BOSCH 17 COLD START SYSTEM Thermo Time Switch This instruction applies only to Robert Bosch thermo time switches Remove the thermo time switch from the engine Engine coolent will spill out when the switch is re moved from the engine Find the design number stamped on the flats of the thermo time switch hous ing Use the design number to find the appropriate test values from the thermo time switch chart below Using an ohmmeter check the resistance at both temperatures indicated on the thermo time switch chart Use warm water to heat the switch required If any resistance does not fall within the specified tolerance replace the thermo time switch
26. cuit Open both valve screws on the pressure tester as C Atmosphere shown Switch the ignition on to run the electric fuel pump Apply the vacuum indicated on the test sheet if any to the warm up regulator with a vacuum pump as shown When the pressure stops increasing read the warm control pressure on the gauge The warm control pressure must be within the tolerance given on the test sheet Turn the ignition off Warm Control Pressure WITH Throttle Activated Valve Test warm control pressure with the warm up regulator plug attached Position throttle plate against idle stop Switch the ignition on to run the electric fuel pump When the pressure stops increasing read the warm control pressure on the gauge the warm control pressure is not within the tolerance given for idle on the test sheet remove both fastening screws on the throttle activated valve and turn the valve in the area of the slots If the idle value cannot be obtained replace the throttle activated valve and readjust to the value given for idle on the test sheet Position the throttle plate by hand about halfway If the pressure does not rise to the partial load value given on the test sheet replace the warm up reg ulator Completely open the throttle to the full load position If the pressure does not drop to the full load value given on the test sheet replace the throttle activated valve and recheck the idle pressure If the warm control pressure does no
27. ded as it may contain information which is no longer valid New pages which do not replace old pages are simply inserted at the appropriate place in each volume ROBERT BOSCH SALES CORPORATION Automotive Service Department Packet J 793 Headquarters Broadview Illinois AIRMAIL Box 66008 O Hare IL 60666 Cable ROBOSPARK BROADVIEWILLINOIS TELEX 72 8466 Regional Offices Paramus New Jersey Atlanta San Francisco Los Angeles and ROBERT BOSCH are trademarks of Robert Bosch GmbH Stuttgart Germany ROBERT BOSCH K JETRONIC SERVICE MANUAL S 2800 SOUTH 25TH AVENUE BROADVIEW ILLINOIS 60153 60 BAYLIS ROAD MELVILLE NEW YORK 11746 345 EAST GRAND AVENUE SOUTH SAN FRANCISCO CALIFORNIA 94080 4131 A DIRECTORS ROW HOUSTON TEXAS 77018 6300 ARIZONA CIRCLE LOS ANGELES CALIFORNIA 90045 20100 CIVIC CENTER DRIVE SUITE 316 SOUTHFIELD MICHIGAN 48076 CONTENTS K Jetronic Pictorial General Information Limited Warranty Policy Warranty Procedure Manufacturing Dates Conversion to Metric Units Metric Conversion Chart Equipment Lists Workshop Manuals Audi BMW Mercedes Benz Porsche Saab Volkswagen Volvo Service Bulletins 12 79 EQUIPMENT LISTS K Jetronic ROBERT BOSCH AUDI K Jetronic Equipment MIXTURE AIR CONTROL FUEL FLOW INJECTION MODEL YEAR UNIT DISTRIBUTOR SENSOR VALVE 0438040 0438100 0438120 0437502 005 007 008 1975 005 1
28. ed and install the exhaust pipe screw plug if fitted 28 ROBERT BOSCH Porsche K Jetronic IDLE SPEED AND ADJUSTMENT 928 Preparation Pressure tester KDEP 1034 must be re moved from the vehicle The electric safety circuit must NOT be bridged The engine must be warm oil temperature 80 90 C If any fuel lines have been opened warm the engine under load to purge the lines of air Idle speed and CO specifications are given on the emissions decal in the vehicle engine com partment Remove the upper part of the air filter 4 clamps Remove the right hand air intake hose to expose the secondary air pump Then remove and plug the pressure hose on the secondary air pump Replace the upper part of the air filter and the air intake hose NOTE When adjusting idle and CO make the adjust ments quickly to prevent the intake tubes from over heating Idle Speed Adjustment Turn the idle bypass screw in front of the intake manifold to adjust idle speed as shown above CO Adjustment Install the CO sensor in the tailpipe Insert mm spherical tip hex wrench see 700 List in the funnel shaped opening of the air filter housing as shown below until the tip of the wrench engages in the top of the spring loaded sealing plug arrow Push the sealing plug down about 18 mm until the plug engages with the idle mixture screw Now turn the idle mixture screw counterclockwise to a value leaner than specification The
29. ehicles since 1978 have fuel distributors which use push valves in the system pressure regulator to maintain pressure Several component tests require special testing procedures for fuel distributors with push valves The Fue Pump sec tion describes in detail how to identify a fuel dis tributor with a push valve in the system pressure regulator Thoroughly clean the fuel fittings before removing any fuel lines Dirt must not enter the fuel system under any circumstances Do NOT bend the steel fuel lines When removing fuel lines always hold the hex fitting on the component with one wrench while loosening the fuel line with another wrench Do not bend the steel type fuel lines K Jetronic Porsche Always use new gaskets seals and O rings when installing components or fuel lines When installing the mixture control unit tighten the fastening screws uniformly Whenever work is performed on the fuel injection system the idle and CO must be adjusted How to use this manual Use the trouble shooting chart to find the cause s for a given symptom The cause column will indicate what component s should be tested Each component test instruction is a complete instruction One component may be checked by following the test instructions for the specific component or the entire system can be checked by following all the component instructions in order The 700 List and Component Location sections will help identify the necessary t
30. es zero resistance on the ohmmeter It must be possible to press the throttle activated valve switch lever a minimum of 0 5 mm farther downward Then check again that the electric circuit is closed zero resistance when the hand throttle lever is fully pulled 26 ROBERT BOSC Porsche K Jetronic IDLE SPEED AND ADJUSTMENT 911 since 1976 Preparation Pressure tester KDEP 1034 must be re moved from the vehicle The electric safety circuit must be bridged The engine must be warm If any fuel lines have been opened warm the engine ER under load to purge the lines of air Idle speed and CO specifications are given on the emissions decal in the vehicle engine compartment On 911SC models N t make sure the oil tank cover is sealing properly A Idle by pass SN leaking oil tank cover will allow unmetered intake air screw j NND J Ss to enter the engine EN Vehicles with Secondary Air Pump Remove and plug the hose on the secondary air pump check valve as shown Vehicles with Vacuum Limiter Remove and plug the ADJUSTING SCREWS air hose which connects with the T connection je above the throttle plate Idle Speed Adjustment Turn the idle bypass screw arrow to adjust idle speed CO Adjustment Install the CO sensor in the tailpipe If the vehicle has a catalytic converter install the sensor in the screw plug hole ahead of the converter Th
31. for exact position of fuel pump components Clean all fuel fittings and clamp the inlet hose to prevent fuel from escaping before removing any fuel pump components On 1973 74 Porsche 911 models remove the inlet hose from the union fitting after loosening the hose clamp On 1975 Porsche 911 models with polyamide fuel lines remove the fuel pump together with the com plete fuel line The inlet fuel line should be removed from the pump on the bench Hold the pump by hand NOT in a vise Torque the union fitting to exactly 16 20 Nm 12 15 ft Ibs Steel Housing with Side Fuel Fitting Clean the fuel fittings on the electric fuel pump Remove and thor oughly clean the fuel pump Mount the clamp for the fuel pump in a vise as shown Do NOT clamp the fuel pump housing itself in a vise Unscrew the check valve from the side of the pump No dirt must enter the pump Install a new check valve using a new gasket and tighten to exactly 16 20 Nm 12 15 ft Ibs Aluminum Housing with Internal Check Valve The check valve on fuel pumps with internal check valves cannot be replaced If the check valve is leaking the complete fuel pump must be replaced Aluminum Housing with Threaded Check Valve Clean the fuel fittings and remove the fuel pump Unscrew the valve insert using a special slotted screwdriver 9 mm wide blade 4 mm wide slot No dirt must enter the pump Install a new check valve using a new O ring and tighten to 0 4
32. from the local airport or weather bureau NOT the corrected barometric pressure reported to the public when reading the warm control pressure graph on the test sheet Bridge the safety circuit Open both valve screws on the pressure tester as shown Switch the ignition on to run the electric fuel pump Apply the vacuum indicated on the test sheet if any to the warm up regulator with a vacuum pump as shown When the pressure stops increasing read the a 8 1034 Fili ere warm control pressure on the gauge The warm control pressure must be within the tolerance given Opening Both Valve Screws on the test sheet use upper curve when testing WITH ring control pressure vacuum Turn ignition off measuring p If the warm control pressure does not fall within the specified tolerance test the supply voltage approxi mately 14 volts available to the warm up regulator If sufficient voltage is available to the warm up reg ulator and the warm control pressure still does not fall within the specified tolerance check the vacuum source for a leak If the high control pressures required for high al titudes cannot be obtained increase system pressure to the high side of the tolerance band see System Pressure If warm control pressure cannot be brought into specification replace the warm up regulator K Jetronic Porsche ROBERT BOSCH 21 to pressure gauge Closing Valve Screw to Wa
33. fuel distributor KDEP 1034 If the warm control pressure does not fall within the specified tolerance test the supply voltage approxi Opening Both Valve Screws mately 14 volts available to the warm up regulator measuring control pressure If sufficient voltage is available to the warm up reg ulator and the warm control pressure still does not fall within the specified tolerance replace the warm up regulator K Jetronic Porsche ROBERT BOSCH 19 ged Warm Up Regulator with Full Load Enrichment nect pressure tester KDEP 1034 see Mounting Pres sure Tester Use the test specification for the specific warm up regulator Cold Contro Pressure The engine must be cold not run for several hours preferably overnight unless otherwise indicated on the test sheet Disconnect the plug from the warm up regulator Open both valve screws on the three way valve of the pressure tester Bridge the safety circuit see E ectric Wiring Diagram Switch the ignition on to run the electric fuel pump Apply the vacuum indicated on the test sheet if any to the warm up regulator with a vacuum pump as shown The cold control pressure indicated on the gauge must be within the tolerance band shown on the appropriate test specification graph Turn the igni tion off Warm Contro Pressure Test warm control pressure with the warm up regulator plug attached Engine temperature is not important Bridge the safety cir
34. he supply voltage approxi mately 11 5 volts ignition off available to the auxil iary air valve at the electric plug If sufficient voltage is available to the auxiliary air valve and the valve still does not close replace the auxiliary air valve 16 ROBERT BOSCH Porsche K Jetronic FUEL PUMP The test point for fuel pump operation depends on the type of fuel distributor Fuel distributors WITH push valves most vehicles since 1978 have two fuel lines connecting with the warm up regulator Fuel dis tributors WITHOUT push valves have only one fuel line connecting directly to the warm up regulator the other fuel line connects to and returns to the gas tank Determine whether the vehicle to be tested is fitted with or without a push valve before proceeding further Disconnect the return fuel line leading to the gas tank at the appropriate test point as indicated below for the specific vehicle Test Point for 911 Disconnect the union fitting on the fuel return line from the fuel distributor see Compo nent Location Connect a temporary hose with an appropriate fitting M 14 x 1 5 to the line coming from the fuel distributor Test Point for 924 Clean and disconnect the union fitting located above the front axle see Component Location Test Point for 928 Disconnect the fuel line from the fuel distributor which leads to the gas tank see Component Location Connect a temporary fuel line with
35. ic Air Flow Sensor Plate Position Remove the rubber boot from the air flow sensor The sensor plate must be flat and pass through the narrowest part of the funnel without touching the sides If the sensor plate touches the sides of the funnel loosen the sensor plate fastening screw Insert the appropriate guide ring see List Hold the fasten ing screw with pliers to prevent the plate from moving down as shown When the guide ring is in place tighten the fastening screw to 5 0 5 5 Nm 3 7 4 0 ft Ibs Then loosen the screw and retorque the fasten ing screw again to the same value The air flow sensor plate must not now be able to be turned by hand Bridge the electric safety circuit see Electric Wiring Diagram Switch the ignition on for 10 seconds to apply control pressure to the plunger The upper edge of the sensor plate should be flush with the beginning of the upper cone as shown The upper edge of the sensor plate may be as much as 0 5 mm below the beginning of the upper cone but must NOT project up into the cone at all Adjust the sensor plate position by removing the air filter and bending the wire loop on the spring stop arrow or turning the adjusting screw 1 Tighten the lock nut before rechecking the sensor plate position K Jetronic Porsche ROBERT BOSCH 13 MMMEM RRoo AIR FLOW SENSOR downdraft only Sensor Plate
36. ilter as shown above Vehicles with Exhaust Gas Recirculation Remove and plug the vacuum hose on the EGR valve Vehicles with Secondary Air Pump Remove and plug the pressure hose on the air pump Vehicles with Vacuum Limiter Remove and plug the air hose which connects with the T connection above the throttle plate Idle Speed Adjustment Turn the idle bypass screw arrow to adjust idle speed The throttle plate position adjusting screws are sealed atthe factory and must not be altered CO Adjustment Install the CO sensor in the tailpipe If the vehicle has a catalytic converter install the sensor 3 in the screw plug hole 1 ahead of the converter This hole must be sealed around the sensor when reading the CO meter Remove the sealing plug from the air flow sensor housing Using wrench KDEP 1035 turn the CO mix ture screw out counterclockwise to a value leaner than specification Then turn the mixture screw in clockwise to bring the CO value into specification Always adjust from the lean side when setting CO After each adjustment remove the wrench and accel erate the engine to stabilize the mixture Acce erating the engine with the wrench in place could bend the air flow sensor lever When the CO adjustment is correct install the plug in the air flow sensor housing install the EGR vacuum hose if fitted install the secondary air pump pres sure hose if fitted install the vacuum limiter air hose if fitt
37. is hole must be sealed around the sensor when reading the CO meter Remove the sealing plug from the air flow sensor housing Using wrench KDEP 1035 as shown below turn the CO mixture screw out counterclockwise to a value leaner than specification Then turn the mix ture screw in clockwise to bring the CO value into specification Always adjust from the lean side when setting CO After each adjustment remove the wrench and accelerate the engine to stabilize the mix ture Accelerating the engine with the wrench in place could bend the air flow sensor lever When the CO adjustment is correct install the plug in the air flow sensor housing install the secondary air pump pressure hose if fitted install the vacuum limiter air hose if fitted and install the exhaust pipe screw plug if fitted K Jetronic Porsche ROBERT BOSCH 27 IDLE SPEED AND CO ADJUSTMENT 924 Preparation Pressure tester KDEP 1034 must be re moved from the vehicle The electric safety circuit must NOT be bridged The engine must be warm oil temperature approximately 80 C If any fuel lines have been opened warm the engine under load to purge the lines of air Idle speed and CO specifications are given on the emissions decal in the vehicle engine compartment Both throttle plate rest positions are set and sealed at the factory The adjusting screws must not be ad justed Clamp the hose between the carbon canister and the air f
38. iston in front of the shim is matched to the housing and is not replaceable If the fuel distributor is fitted WITHOUT a push valve remove the screw plug and change the adjusting shim as required A 0 1 mm increase in shim thickness will increase system pressure 0 15 bar 2 2 PSI Use a new copper gasket when installing the screw plug Tighten the screw plug to 13 15 Nm 10 11 ft Ibs Vote The piston in front of the shim is matched to the housing and is not replaceable Fuel distributor housing O ring 7 Control piston 7 Spring Retainer 7 Retaining ring 7 Spring 7 Shims 10 Valve needle 11 Seal ring 12 Screw plug 13 Screw plug 14 Flat seal ring ONOTawWN a from fuel distributor b from warm up regulator fuel return 22 ROBERT BOSCH Porsche K Jetronic LEAKAGE TEST The engine must be warm but not hot Connect pressure tester KDEP 1034 see Mounting Pressure Tester Bridge the electric safety circuit see Electric Wiring Diagram Open both valve screws on the three way valve as shown Turn the ignition on When warm control pressure is reached turn the ignition off After the specified time the control pressure must NOT be less than the value given on the test sheet for eakage test control pressure drops too quickly close the valve leading to the warm up regulator and repeat the leakage test If closing the valve leading to the warm up regulator brings the pres
39. n turn the mixture screw clockwise to bring the CO value into specifica tion Always adjust from the lean side when setting CO After each adjustment remove the wrench and accel erate the engine to stabilize the mixture and cool the intake tubes When the hex wrench is withdrawn the spring loaded sealing plug seals the opening to prevent unmetered air from entering the engine Accelerating the engine with the wrench in place could bend the air flow sensor lever When the CO adjustment is correct install the secon dary air pump pressure hose K Jetronic Porsche ROBERT BOSCH 29 MOUNTING PRESSURE TESTER Preparation Pressure tester KDEP 1034 was initially supplied with a three way changeover valve operated by a single lever In newer models this lever is replaced by a directional control valve with two hol low screws The connections on the directional con trol valve and the changeover valve are numbered the same Fuel Distributor The pressure tester is connected in the control pres sure line between the warm up regulator and the fuel distributor as shown Warm up Regulator For 911S models with throttle activated valve Clean the fuel fittings on the warm up regulator At the fuel distributor unscrew both the control pressure line coming from the throttle activated valve and the control pressure line coming from the warm up reg ulator Using adapter KDEP 1034 10 1 and one of the original hollow
40. necting hose Attach connection 2 to the pressure gauge with the other connecting hose Bleed the tester as indicated below For 928 models Clean the fuel fittings on the control pressure line at the warm up regulator Remove the control pressure line from the warm up regulator Using the hose included in connecting parts set KDEP 1034 11 connect the warm up regulator outlet with connection 1 of the tester valve Attach the two piece connector included in connect ing parts set KDEP 1034 11 to the control pressure line Using the tester hose connect the control pres sure line to connection 3 of the tester valve Attach connection 2 to the pressure gauge with the other connecting hose Bleed the tester as indicated below Bleeding the Tester Disconnect the electric plug from the warm up regulator and the auxiliary air valve With the tester hoses fully extended let the gauge hang down under its own weight so that the gauge is lower than the fuel lines Bridge the electric safety circuit and switch the igni tion on to run the fuel pump If the changeover valve is used move the control lever back and forth about five times between position 2 and 3 remaining in each position about 10 seconds If the directional control valve is used open and close hollow screw number 1 about five times remaining in each position approximately 10 seconds Turn the ignition off Hang the gauge from one of the struts under the engine hood or
41. on on for 10 seconds to apply control pressure to the plunger The upper edge of the sensor plate should be flush with the beginning of the upper cone as shown The upper edge of the sensor plate may project up as much as 0 5 mm above the beginning of the upper cone but the lower edge of the sensor plate above the chamfer must not project down into the lower cone at all If the sensor plate is too high very carefully tap the guide pin arrow deeper into the housing Caution Make this adjustment very carefully Adjustment sev eral times in both directions will loosen the press fit of the pin possibly causing engine damage K Jetronic Porsche ROBERT BOSCH 15 AUXILIARY AIR VALVE Cold Operation Test the auxiliary air valve first with the engine cold not run for several hours preferably overnight Disconnect the electric plug from the aux iliary air valve and from the warm up regulator Re move both air hoses from the auxiliary air valve Using a flashlight and a mirror look through the valve as shown When the engine is cold the valve must be open If not replace the auxiliary air valve Warm Operation Attach the electric plug to the auxil iary air valve Bridge the electric safety circuit see Electric Wiring Diagram Turn the ignition on The auxiliary air valve must be completely closed within 10 minutes If the auxiliary air valve does not completely close within 10 minutes test t
42. ools and help locate vehicle components to be tested Specific compo nent removal and installation information can be found in Mounting the Pressure Tester and Com ponent Repair The Electric Wiring Diagram section shows how to bridge the electric safety circuit to apply voltage to electrical components without run ning the engine Replacement parts lists and com plete test specifications can be found at the end of the workshop manual ROBERT BOSCH 3 TEST EQUIPMENT TOOL PART NUMBER APPLICATION Pressure Tester KDEP 1034 tests all working pressures Connecting Parts KDEP 1034 10 pressure tester fuel line adapters KDEP 1034 10 3 for various engines KDEP 1034 11 Wrench KDEP 1035 adjusts idle mixture CO all except 2 manufacturer tool adjusts idle mixture CO for 928 Guide Rings KDEP 1040 10 for 80 mm diameter sensor plates KDEP 1040 14 for 110 mm diameter sensor plates Comparative Tester KDJE 7451 tests injectors and fuel distributor for equal delivery Accessory Set KDJE 7451 25 for use with KDJE 7451 when engine is fitted with steel fuel lines Valve Tester KDJE 7452 tests injectors 1500 cc Graduate commercially available measures fuel pump delivery Tachometer commercially available measures engine speed for idle and CO adjustment CO meter commercially available measures CO for fuel mixture adjust ment Vacuum Pump commercially available for testing full load enriched warm up regulators 4 ROBERT BOSCH Porsche
43. other suitable support and proceed with the appropriate pressure test ROBERT BOSCH 31 K Jetronic Porsche FUEL DISTRIBUTOR REPAIR 911 924 Removal Clean all the fuel fittings on the fuel dis tributor Remove all fuel connections Unscrew the three fastening screws and remove the fuel dis tributor from the air flow sensor housing or throttle valve housing Be careful not to let the plunger fall out Keep shims and springs together Installation When installing the 911 air flow sensor housing on the intake manifold tighten the fastening screws until each spring is compressed then loosen each screw one turn Rinse the plunger in an appropriate solvent and reinstall the plunger in the fuel distributor Install the fuel distributor on the air flow sensor using a new gasket as shown Tighten the fastening screws to exactly 3 2 3 8 Nm 2 4 2 8 ft Ibs Attach all fuel lines except one arrow to the fuel distributor using new gaskets Bridge the electric safety circuit see Electric Wiring Diagram Turn the idle mixture screw in clockwise slowly without pushing on the air flow sensor lever until fuel just starts to come out the open fuel outlet Then turn the screw out counterclockwise turn Reconnect the fuel line to the fuel distributor Run the engine until it reaches operating temperature and make the final mixture adjustments as indicated in Idle and CO Adjustment 32 ROBERT BOSCH Porsche K Je
44. r 4 Warm up Regulator 5 Fuel Pump Protective Cover above Fuel Fuel Accumulator and Fuel Filter located in Pump No 1 below right rear wheel well Fuel Pump No 2 located under right rear Fuel Pump Test Point arrow Bridging Electric Safety Circuit relay No XVII fender arrow 8 ROBERT BOSCH Porsche K Jetronic VACUUM DIAGRAM 911 since 1976 5 Warm up Regulator 6 Ignition Distributor 7 Exhaust Gas Recirculation Valve only California 8 Changeover Dump Valve 9 Vacuum Limiter ium Takeoff for Auxiliary Air Valve and Auxiliary Air Device Takeoff Power assisted System K Jetronic Porsche ROBERT BOSCH 9 TROUBLE SHOOTING CHART Cause s Vacuum system leaking see Vacuum Leaks Air flow sensor plate and or control plunger not moving smoothly see Air Flow Sensor Movement Air flow sensor plate stop incorrectly set see Air Flow Sensor Gin Auxiliary air valve does not open see Auxiliary Air Valve Auxiliary air valve does not close see Auxiliary Air Valve Electric fuel pump not operating see Fue Pump Defective cold start system see Co d Start System Leaking cold start valve see Co d Start System Incorrect cold control pressure see Warm up Regulator Warm control pressure too high see Warm up Regulator Warm control pressure too low see Warm
45. rm up Regulator measuring system pressure screw plug copper gasket ev shim fuel distributor spring Control piston SYSTEM PRESSURE REGULATOR without push valve 547 8 12 14 SYSTEM PRESSURE REGULATOR with push valve SYSTEM PRESSURE Testing System Pressure Engine temperature is not important Connect pressure tester KDEP 1034 as indicated in Mounting Pressure Tester Bridge the electric safety circuit see Electric Wiring Diagram Close the pressure tester valve screw leading to the warm up regulator as shown Turn the ignition on Read the system pressure on the gauge and compare this reading with the value Shown on the test sheet If system pressure is lower than the value given on the test sheet test the fue pump If the fuel pump is within specification adjust the system pressure as indicated below If system pressure is higher than the value shown on the test sheet check the gas tank return line for a restriction If there is no restriction in the return line adjust the system pressure Adjusting System Pressure If the fuel distributor is fitted WITH a push valve unscrew the large screw plug with attached push valve assembly Change the adjusting shim as required A 0 1 mm increase in shim thickness will increase system pressure 0 15 bar 2 2 PSI Use a new O ring and copper gasket when reinstalling the large screw plug and push valve Note The p
46. sor plate to the setting point value Push each button again Every injector must now be within the tolerance given for delivery on the d e Delivery Chart not see Test Results below IDLE DELIVERY CHART Cylinders Setting Point Delivery ccimin 4 5 6 6 0 6 0 6 8 8 6 0 6 0 7 0 ROBERT BOSCH Porsche K Jetronic Part Load Test Turn the load range knob to the right to read the right rotameter tube Press button number 1 Move the sensor plate by hand until the right rotameter tube shows the value given for setting point on the Part Load Delivery Chart Fix the sensor plate in this position Push each button until the lowest delivery is obtained and then readjust the sensor plate to the setting point value Push each button again Every injector must now be within the tolerance given for delivery on the Part Load Delivery Chart not see Test Results below PART LOAD DELIVERY CHART Cylinders Setting Point Delivery ccimin ccimin 4 5 6 8 40 0 40 0 44 0 Full Load Test Move the sensor plate to its maximum deflection Push each button until the highest delivery is obtained and then readjust the sensor plate until the rotameter tube reads the next lower setting point value on the Fu Load Delivery Chart Push each button again Every injector must be within the appropriate tolerance given for delivery on the Full Load Delivery Chart not see Test Results below FULL LOAD DELIV
47. sure into specification replace the push valve or for fuel distributors without push valves re place the warm up regulator and or throttle activated valve if fitted see Component Repair If closing the valve leading to the warm up regulator does NOT bring the pressure into specification there is a leak in the system pressure circuit Check the cold start valve for leakage see Co d Start Valve Test the injectors for leakage see Testing njectors If neces sary replace the check valve on the electric fuel pump and or the control piston O ring on the system pres sure regulator in the fuel distributor see Fue Dis tributor Repair TESTING INJECTORS Remove the injectors from the engine Connect each injector to valve tester KDJE 7452 as indicated in the operating instructions included with the tester Injec tors should be tested for opening pressure leakage and spray pattern Replace any defective injectors to pressure gauge from fuel distributor KDEP 1034 regulator Opening Both Valve Screws measuring control pressure to pressure gauge from fuel distributor to warm up regulator KDEP 1034 Closing Valve Screw to Warm up Regulator measuring system pressure K Jetronic Porsche ROBERT BOSCH 23 Load Range Knob Injector Buttons Gas Tank Return Hose COMPARATIVE TEST Setting up the tester Comparative tester KDJE 7451 is
48. t fall within the specified tolerance test the supply voltage approxi mately 14 volts available to the warm up regulator If sufficient voltage is available to the warm up reg ulator and the warm control pressure still does not 20 ROBERT BOSCH Porsche K Jetronic fall within the specified tolerance check the vacuum source for a leak gt gt Atmosphere warm control pressure cannot be brought into specification replace the warm up regulator Warm Up Regulator with Full Load and Altitude Compensator Connect pressure tester KDEP 1034 see Mounting Pressure Tester Use the test specifica tion for the specific warm up regulator Cold Control Pressure The engine must be cold not run for several hours preferably overnight unless otherwise indicated on the test sheet Disconnect the plug from the warm up regulator Open both valve screws on the three way valve of the pressure tester Bridge the safety circuit see Electric Wiring Diagram Switch the ignition on to run the electric fuel pump Apply the vacuum indicated on the test sheet if any to the warm up regulator with a vacuum pump as shown The cold control pressure indicated on the gauge must be within the tolerance band shown on the appropriate test specification graph Turn the ignition off to pressure gauge Warm Control Pressure Test warm control pressure with the warm up regulator plug attached and the engine warm Use station pressure
49. tire lever movement If not the air flow sensor plate is not moving freely see below Now push the sensor plate down rapidly almost back to its rest position The plunger will not follow the rapidly moving sensor plate but the shock of the plunger hitting the sensor plate lever when it does come down must be felt If this cannot be felt the plunger is not moving freely see below Fully lift the air flow sensor plate up to its maximum deflection When released the sensor plate must fall back to its rest position after bouncing once or twice on the spring stop If not the air flow sensor plate is not moving freely see below If the air flow sensor plate does not move freely loosen the mounting screws around the air flow sensor housing to check if housing warpage is caus ing the lever to bind If necessary replace the gasket under the air flow sensor and uniformly tighten the fastening screws If the plunger does not move freely remove the fuel distributor from the air flow sensor see Fue Dis tributor Repair Remove the plunger from the fuel distributor If it is necessary to blow compressed air in the control pressure connection hole to free the plunger hold the plunger with your hand as shown to prevent the plunger from falling out of the fuel dis tributor Clean the plunger with an appropriate solvent If the plunger still binds in its barrel replace the fuel distributor 12 ROBERT BOSCH Porsche K Jetron
50. tronic FUEL DISTRIBUTOR REPAIR 928 Removal Remove both intake hoses and the upper part of the air filter 4 clamps Remove the pressure screw in the intake manifold Remove the fastening screws in the air filter bowl arrows Then remove the filter bowl to the right Clean all the fuel fittings on the fuel distributor Remove all fuel connections Unscrew the three fastening screws and remove the fuel dis tributor from the air flow sensor Be careful not to let the plunger fall out Installation Rinse the plunger in an appropriate solvent and reinstall the plunger in the fuel dis tributor Install the fuel distributor on the air flow sensor using a new gasket as shown Tighten the fastening screws to exactly 3 2 3 8 Nm 2 4 2 8 ft Ibs Attach all fuel lines except one arrow to the fuel distributor using new gaskets Bridge the electric safety circuit see Electric Wiring Diagram Turn the idle mixture screw in clockwise slowly without pushing on the air flow sensor lever until fuel just starts to come out the open fuel outlet Then turn the screw out counterclockwise turn Reconnect the fuel line to the fuel distributor Run the engine until it reaches operating temperature and make the final mixture adjustments as indicated in Idle and CO Adjustment K Jetronic Porsche ROBERT BOSCH 33 FUEL PUMP REPAIR Remove any dirt protection plates to expose the fuel pump See Component Location
51. tronic OOOO TEST SHEET 911T mm FUEL PUMP min 750 cc in 30 seconds COLD CONTROL PRESSURE CONTROL PRESSURE AMBIENT TEMPERATURE 0 438 140 001 WARM CONTROL PRESSURE throttle plate adjustment Idle checking value 2 8 3 0 bar setting value 2 85 2 96 bar Part load 3 4 3 8 bar Full load 2 6 3 0 bar SYSTEM PRESSURE Checking Value 4 5 5 2 bar Setting Value 4 7 4 9 bar LEAKAGE TEST Minimum pressure after 20 minutes 1 0 bar INJECTION VALVE OPENING PRESSURE 2 5 3 5 bar with 0 6 bar maximum variation in set Idle speed and CO specifications are given on the emissions decal in the vehicle engine compartment K Jetronic Porsche ROBERT BOSCH 41 gh 911 911 TEST SHEET min 850 cc in 30 seconds FUEL PUMP COLD CONTROL PRESSURE 55 10H1NOO 38095384 TONLNOD AMBIENT TEMPERATURE AMBIENT TEMPERATURE 0 438 140 009 0 438 140 008 CKA 7 38098384 10H1NOO AMBIENT TEMPERATURE 0 438 140 017 033 K Jetronic Porsche 42 ROBERT BOSCH WARM CONTROL PRESSURE 1974 75 model with throttle activated valve Idle checking value 2 8 3 0 bar setting value 2 85 2 95 bar R Part load 3 4 3 8 bar Full load 2 6 3 0 bar 1974 75 model with vacuum enriched full load warm up regulator Without vacuum 2 7 3 1 bar With idle speed vacuum 3 4 3 8 bar 1976 model Without vacuum 2
52. used to measure equal delivery between injectors The comparative test will also determine whether a problem involves an injector or the fuel distributor Set the tester on a solid surface next to the vehicle Level the tester and install the return hose in the gas tank If inflexible steel fuel lines are used on the vehicle remove the steel lines from both the injector and the fuel distributor and replace them with flexible adapter hoses from accessory kit KDJE 5471 25 Remove the injectors from the engine and insert each injector in order into the tester fuel lines Tighten the knurled coupling to secure each injector Remove the rubber boot updraft or air filter downdraft from the upper part of the air flow sensor Bridge the electric safety circuit see Electric Wiring Diagram Switch the ignition on to operate the fuel pump Move the sensor plate to its maximum deflection Press each of the eight buttons while turning the load range knob back and forth until the rotameter tubes are completely bled Return the sensor plate to its rest position Idle Test Turn the load range knob to the left to read the left rotameter tube Press button number 1 Move the air flow sensor plate by hand until the left rotameter tube shows the value given for setting point on the d e Delivery Chart Fix the sensor plate in this position Push each button one after the other until the lowest delivery is obtained and then readjust the sen
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