TomcoTechtips
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1.2. MNK 4 al 4 Fir dn AMAWA ad odpi opa Z TM ISSUE 2 How to get the car to tell you what s wrong Changing technology doesn t always mean that your job will be more difficult it does mean it will be different For instance if the car s performance is poor it may not be due to plugs or points It could be one of the new performance controls such as EGR valves O Sensors coolant temperature sensors or ported vacuum switches Actually today s newer cars with their on board computers or electronic control modules ECMs make it easier to diagnose perfor mance problems than ever before And believe it or not one of the most important tools you need is a paper clip If you know where to put the paper clip you can literally get new GM cars to tell you what s wrong with them What we will do here is give you a brief by the numbers way to read the on board computers s self diagnostic system for Chrysler and GM Each is a little different We will also give you a listing of the service codes for these car makers This listing will give you a leg up on solving performance problems on today s newer Cars GENERAL MOTORS 1 Locate the Assembly Line Connecting Link ALCL You will probably find it under the dash This is where the computer at the assem bly plant hooks up to the car to check out the systems 2 Turn the ignition key to the ON position but do not start the engine 3 Place the ends of a paper cli
3. the intake manifold or air filter housing Measures air fuel mixture temperature Signals computer to adjust injector for damage and corrosion when trouble codes indicate problem in this circuit Failure symptoms Check Engine light is oncontinuously hesitation poor mileage or strong exhaust odor w TOMCO solutions 1s d to performance oxXYGENSENSOR Locatedon exhaust manifold Measures amount of oxygenin exaust Signals on board computer to adjust fuel mixture Check and replace according to manufacturer s spectations Bad oxygen sensor may cause Check Engine lightto light up poor performance reduced fuel economy andwill damage catalytic converter FUEL INJECTOR Located in the TBI assembly Meters and atomizes fuel delivered to engine Inspect every 25 000 30 000 miles for proper spray pattern and leakage Failure symptoms Nostart flooding hesitations exhaust odor IDLE AIR CONTROL Located on TBI unit or throttle body PFI engines Minimizes the variation in engine speed under various idle load conditions Check for proper idle control free pintle movement and corrosion on con nectors every 25 000 30 000 miles Failure systems Stalling high idle speeds Check Engine lighton continuously EGR VALVE POSITION SENSOR Located on back of EGR valve Signals computer to adjust EGR valve opening Inspect when driveabilty problems occur Check for corrosion on terminals every 25 000 30 000 miles Failu
4. all codes in memory have been displayed FORD Since mid year 1978 models Ford has used several different versions of two basic engine control computer system the electronic Engine Control EEC series and the Micro processor Control Unit MCU system Some early versions did not have self diagnosis capabilities The Latter systems can be checked using an analog pointer type voltmeter or scan tool These systems will be covered in a future issue of TOMCO TECH TIPS The following chart lists the service codes and the components or circuits they indicate for Chrysler and GM We have condensed many pages of information in order to give you this basic trouble shooting tool Specific service codes may be found in service manuals for each model and year This chart is valuable to get you headed the right direction and it is much handier than searching through large service manuals ECM TROUBLE CODE CHART SERVICE CODE 0 1 8 11 12 13 14 15 16 17 19 21 22 23 24 25 26 27 28 31 32 33 34 35 36 37 41 42 43 44 45 46 47 CHRYSLER Oxygen Feedback Sys Lean Oxygen Feedback Sys Rich Knock Circuit Distributor Signal Battery Feed to Logic Module Disconnected Recently MAP Sensor vacuum MAP Sensor electrical Vehicle Speed Sensor Battery Voltage Sensing Detonation Sensor Engine Cooling Sys O2 Sensor ECT Sensor Charge Temp Sensor Throttle Body T
5. emp Sensor P Auto Idle Speed Control n Injector 1 amp 2 Fuel Injector Driver Injector 3 amp 4 Fuel Control Canister Purge Solenoid Circuit Power Loss Lamp Power Limit Lamp A C Wide Open Throttle Cut Relay Circuit EGR Solenoid Speed Contol Solnoid Speed Control Servo Radiator Fan Relay Circuit Wastegate Conrol Solenoid Trans Lockup Solenoid Baro Read Solenoid Shift Indicator Lamp Battery Charging Sys Altemator Field Control Ignition amp Fuel Control Interface Spark Control Logic Module Battery Temp Overboost Battery Voltage Sensing Battery Voltage Sensing Auto Shut Down Relay GM No Distributor Ref Pulse or Engine Speed Active O2 Sensor Circuit Coolant Sensor High Coolant Sensor Low TPS Idle amp WOT Switch Error TPS Fuel cut off Solenoid M C Circuit Solenoid MAT Sensor Air Fuel Solenoid Vehicle Speed Sensor MAT Sensor Air Switch Solenoid Wastegate Elec Sig Open Waste gate Hi MAP Overboost MAP Low EGR Baro Sensor EVRV EGR Mass Alr Flow Sensor MAP Sensor Mass Air Flow Sensor MAP Sensor Differential Pres Vacuum ISC Idle Air Control Burnoff Diagnostics No Distrib Ref Signal Cam Sensor Failed Cylinder Selsect Error EST Monitor Error By Pass Line Error Electronic Spark Control Dist or C 3 Sys Error Fuel Cutoff Solenoid Electronic Spark Control Lean Exhaust 44 amp 45 O2 Sensor Rich Exhaust 44 amp 45 O2 Sensor New EVP Se
6. nsor helps eliminate sudden acceleration problems Some 1983 through 1986 fuel injected Ford cars with 3 8 or 5 0 liter engines and automatic transmission are experiencing sudden acceleration The problem is believed to be caused by the failure of the EGR valve position The sensor in question is an early design for which Ford now has a new specifi cation Tomco Inc now offers an EGR valve position sensor with an improved design which conforms to Ford s latest specifcations Our design has greater durability anda longer service life If you find one of the old models on a car you are servicing it should be replaced with the new design A note of caution There are replacement EGR valve position sensors in the aftermarket which are the very same units in question That is they have the old design which is no longer specified by Ford You will know when you come across one of of these because the serial number has been ground off the top of the housing New Tomco Inc EVP Sensor on left is white and has a rounded housing Old model on right has square housing Also notice that the old model on the right has had the serial number machined off Do not install an EVP Sensor that looks like this How to service the GM TBI pressure regulator There is no need to replace the pressure regulator on GM TBI units Tomco Inc offers a kit that allows you to safely service this component The kit also reduces your parts cos
7. p in the A and B terminals of the vehicle s ALCL Fig A This will GM DIAGNOSTIC TERMINIAL ALCL CONNECTOR 1980 1 24 3L 1981 f i By simply inserting the two open ends of a paper clip in the proper teminal of the ALCL on GM cars the mechanic can start the trouble code sequence The ECM may be damaged ifthe wrong terminals are used When in doubt consult the proper service manual GROUND activate the system and the Check Engine light will begin to flash Each flash is a digit in a code number it will flash once pause then flash twice This code is 12 and it will flash the code three times 4 Read the flashing codes After the three code 12 s the light will begin to flash service codes for components or systems which have malfunctioned in the last 50 starts These codes will be repeated three times each If no malfunction exits the code 12 will flash until you remove the paper clip CHRYSLER You don t even need a paper clip to get service codes from Chrysler cars 1 Turn the ignition key ON OFF ON OFF on within 5 seconds This activates the system and the POWER LOSS lamp will light up for two seconds immediately after this it will begin flashing the service codes always starting with code 88 2 Count the flashes made by the POWER LOSS light Each one is two digits like GM There is a short pause between digits and a 4 second pause between codes The light will continue to flash until
8. re symptoms Poor fuel economy sudden acceleration hesitation IDLE SPEED CONTROL Attached to carburetor or TBI unit Adjusts throttle opening to maintain proper idle speed Inspect and adjust during tune up 25 000 30 000 miles Check for corrosion onterminals Failure symptoms Engine stalling and or dieseling EGR VALVES Located on exhaust manifold EGR valves recirculate exhaust gas to intake manifold to cool peak combustion temperature Reduce NOX emissions Inspect ever 12 000 to 15 000 miles Bad EGR valve may cause roughidle overheating loss of power and poor fuel economy PORTED VACUUM SWITCH Located in vehicle cooling system Controls various vacuum actuated components including EGR valve Inspect for damage every 6 000 to 8 000 miles Testif engine overheats Damaged or broken swtches cause poor perform ance reduced fuel economy surging and engine knock Q COOLANT TEMPERATURE SENSOR Located in vehicle coolant system Major component of computer controlled engines Measures engine temperature Signals computer to adjust fuel mixture Inspectevery 12 000 to 15 000 miles Bad sensors may cause poor perform ance reduced fuel economy and hard starting NEW EGR VALVE TESTER AVAILABLE FROM TOMCO This hand heldtester allows positive testing of all types of EGR valves It is easy to use inexpensive and operates on shop air Itcomes with complete instructions and storage case TOMC O Ginc
9. t while allowing you to bill more labor Kit 3 272 contains two long screws When dismantling a pressure regulator first remove only two short screws Now remove the long screws which contol the extension of the regula tor spring This allows the housing to be opened safely These screws also position the stamped housing as the heavy regulator spring is compressed and the short screws are installed during reas sembly Also included are instruc tions and a special thread com pound to prevent the screws from loosening This kit complements our TBI repair kit 5525 which contains gaskets seals pressure regulator diaphragm and filter Complete instructions are included Q THROTTLE POSITION SENSOR Outside of most carburetors and TBI units inside some GM carbs Signals computer how much air is being con sumed Check operation adjust voltage and inspect for corrision on connectors every 25 000 30 000 miles Failure symptoms Hesitations tip in surge engine pinging no torque converter lock up Check Engine lightis on SEND FOR NEW ENGINE PERFORMANCE CONTOL TAPE Get an overview of engine performance controls in this 40 minute tape Use it as an update for yourself or your mechanics The tape covers location function and troubleshooting tips for the 10 engine performance controls pictured on this page Italso demon strates the new EGR valve tester AIR CHARGE amp MANIFOLD AIR TEMPERATURE SENSOR Locatedin
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