1993 GMC Sierra 4.l V6, TBI. Service engine light comes on. Code 12 on diagnostic. The engine will not stay running when cold and the truck lurches when accelerating. I changed the air filter and fuel filter, no change. I replaced the fuel pressure regulator and the problem went away for a few months. I think the one of the fuel injectors is bad or not getting power. I need to know how to test the injectors.
The fuel injectors are working. I miss counted the flashes. It is code 32, not 42.The fuel injectors are working. I miss counted the flashes. It is code 32, not 42.
code 42 means the EST (electronic spark timing) control did not change when the ECM (engine computer) applied bypass voltage to the ignition module. which means that your igniton module timing did not change when the computer bypassed it. you may have a problem there (ignition module), did the injectors look good? spray?code 42 means the EST (electronic spark timing) control did not change when the ECM (engine computer) applied bypass voltage to the ignition module. which means that your igniton module timing did not change when the computer bypassed it. you may have a problem there (ignition module), did the injectors look good? spray?
remove the air breather and look in throttle bore (carefully) while engine is running, do both injectors squirt a cone shaped stream? if not I would remove them and clean them with a good carburator cleaner. have you checked the IAC (idle air control) valve? code 12 means it is in the diagnostic moderemove the air breather and look in throttle bore (carefully) while engine is running, do both injectors squirt a cone shaped stream? if not I would remove them and clean them with a good carburator cleaner. have you checked the IAC (idle air control) valve? code 12 means it is in the diagnostic mode
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Ok code 32 is the EGR (exhaust gas recirculation) this does not mean that the EGR valve is bad right off, check it and see if it is stuck in the open position, remove the vacuum line see if it moves, it should not. It is supposed to open at highway speed to recirculate exhaust gases and burn them, if the valve is stuck open the engine will not idle because it upsets the air mixture too much, if you remove the valve and see its open, then replace it.
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Hook up a professional grade scan tool and read DTC'S - diagnostic trouble codes. then get service repair info. www.alldatadiy.com and do the diagnostic tests for that code. Thats how a professional tech does it.
Have you checked to be sure the idle air control is working properly and also the engine temp control sw. The iac only comes on to maintain the idle when the engine is cold. The ect sw monitors the outside temp and tells the computer how much fuel to put to the engine. Hope this helps.
Low pressure from fuel pump, when the pump is cold the pressure increases, as it warms up the pressure drops (this happens in a pump that is going out) the normal pressure should be at 40 with the key on and engine not running, when started the pressure should stay around 36, any less it won't idle and may run as long as you hold the pedal down. The injectors are opened electronicaly, so as long as there is fuel flow the engine gets fuel to run.So check the fuel pump, soundslike you need a new one
could be o2 sensor you need to have it scanned get code if you go to any local autopart store they will scan it for free and give you a print out of your code
Oxygen sensor[s],map sensor and fuel pressure regulator.Although you should have a check engine light "on" with any sensor malfunction.I would look at fuel lines for a leak under vehicle.
Disconnect the battery for a minuit and turn on the light's to power down any electrical power. Reconnect the battery and that should clear the "servie engine light soon",but if there are any DTC codes, the "Service engine light" will come back on.
On board diagnostic (OBD) was designed on vehicles equipped with electronic fuel injection so you can generally retrieve the codes yourself. No need buying a scanner or running to any parts stores to check the Engine Light. This system is called obd1 and applies to most vehicles made before 1995 for domestics and 1993 on imports. For GM domestic vehicles made before 1995, the diagnostic connector is located under the dash panel by the driver side. To get the check engine codes to flash in your dash panel, use a jumper wire or a paper clip and connect terminals A and B of the diagnostic connector. Turn your ignition key on with engine off and the codes should start to blink. All codes should start with code 12 which is one long flash followed by 2 short flashes. This code 12 means the diagnostic system is normal and will repeat itself continuously if there are no trouble codes. Otherwise, code 12 will flash 3 times before flashing the fault codes. the codes can be erased or cleared by disconnecting the battery negative terminal for 1 minute and reconnect. Just make sure to check your service manual in case you have electronic equipment such as radio or clock that needs reprogramming in which battery disconnection is not recommended. Finally after performing repairs on the culprit code, always go for a road test to confirm if the problem is fixed. Good luck and hope this help, here is a link to the DTC codes.http://www.gmtuners.com/OBD1_DTC.htm
I meant code 42
The fuel injectors are working. I miss counted the flashes. It is code 32, not 42.
I haven’t had a chance to look at the EGR yet, but your suggestion seems right. I think I’m on the right track with it now.
Thanks
code 42 means the EST (electronic spark timing) control did not change when the ECM (engine computer) applied bypass voltage to the ignition module. which means that your igniton module timing did not change when the computer bypassed it. you may have a problem there (ignition module), did the injectors look good? spray?
remove the air breather and look in throttle bore (carefully) while engine is running, do both injectors squirt a cone shaped stream? if not I would remove them and clean them with a good carburator cleaner. have you checked the IAC (idle air control) valve? code 12 means it is in the diagnostic mode
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