Could be a bad fuel injector, or much worse- a burnt valve. If it's not ignition-related, it's either fuel or mechanical. You'll need to narrow it down to one cylinder if you can. If not one offending cylinder, could be a bad O2 sensor. Others here will probably offer more accurate diagnoses, but that's where I would start. Good luck.
Chris
90 & 94 GXE'sChris,
Thanks for the quick info. Do you have any suggestions on how to narrow this down without throwing random parts at it? I did unplug the battery for 30 mins, reconnected and same issue. I suspect something electrical as the vehicle literally developed this problem overnight while parked. Thanks again for the input.
Derek
Chris H wrote:
How old is the fuel filter? Replace it if it's old. Since you have spark at each plug, the other necessities are fuel and air. Check the air filter, and then check the injectors.
You can use a piece of rubber hose to listen to each cylinder as the engine runs, and each injector should make a "pfft pfft" sound. Another test is to unplug each injector (engine off) and put an ohm meter across the two leads. I don't know what it should read, but they should all be the same. If one is wildly different, it's probably bad. But, you should have a Check Engine light if one of the injectors has failed. You could also unplug each injector and see if the car's performance changes. If one is bad, and you pull another cable, you'll probably stall the car.
Bill G '91 SE Auto
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