1991 Cavalier Hesitation

[Frustrated_Steve]

I am the proud(?) owner of a 1991 Cavalier VL 2.2, that has made me quite frustrated as of late. My car recently acquired a stalling problem which caused me to replace the IAC, TPS, spark plugs, plug wires, air filter, and fuel filter. After the problem persisted, I changed the ignition control module. That seemed to be the end of my stalling problem...enter hesitation problem.

I decided to celebrate the rebirth of my car by taking it on a short 150km drive to another city. Once I had been driving at highway speeds (110kms/hour) for about 15 minutes, the car started to hesitate and buck when the engine was under any noticeable load. I also noticed that the engine seemed to be idling a little higher than what I was used to. This may be unrelated, but the 'shift' light also flashes on and off while the engine is bucking even while coasting in neutral. As soon as this problem was noticed, the car was turned around for a long shameful drive home.

All the way home my car continued to hesitate, buck and jerk me around in my car. Once I was back in the city, the problem persisted at lower speeds (50-60kms/hour). It never did stall on the way home which was a small victory in my mind. I was still not impressed to say the least!

I was thinking that the problem may be the fuel pump. Is there any way of testing the fuel pump while in the tank? I would rather not change it if the problem is something else. I have yet to see the 'Check Engine' light come on (unless while starting the car - the light does work). Tomorrow, I plan on replacing the O2 sensor, and checking the gap on the new spark plugs I have installed.

Does anybody have any other ideas as to what may be the culprit? Any information would be greatly appreciated.

Steve

[z24-xavier]

hmm... could be alot of things.. control module, coils, crank position sensor, timing belt (ohc or ohv?), vaccuum leak... it's really hard to say about the fuel pump, but i know you can get a fuel pressure tester at most parts houses.. hey that could be another idea.. fuel pressure regulator?

[Frustrated_Steve]

I am going to replace the coils tomorrow, just in case. I checked my EGR valve, and it does need to be replaced. Could this be the problem?

[boarder_punk]

Yes, the EGR could definitely be a part of the cause.

You can also get a Digital Multi-Meter and an Amp Clamp and use that around the wiring to the fuel pump to see if the fuel pump is drawing the correct amount of amperage (sorry I can't tell you the specs on that off the top of my head, you should be able to find it in a service manual though).

Another thing is you could check the injector (Throttle Body Injection...1 injector I am assuming?).

[Frustrated_Steve]

Thank you for confirming my suspicion regarding the EGR valve. You are correct, I have one injector. I will check that too. Checking the amperage draw is also a great idea. Looks like I have another busy day ahead of me! Thanks for the input, I will let you know how it all checked out.

Steve

[teg_b18c1]

My buddy had the same problems it was the coil pack.

[bossdj__]

That sounds almost exactly what the '94 jeep i had started doing. Would run fine for about 15 mins then shift light, bucking and so on, lasted a few mins up to almost an hour until check engine light came on. Turned out to be the O2 sensor, the Ecu was starving the engine to comp for the amount of air that wasn't really there or something i guess.

[94VL]

I had an S10 that did similar things...it was a bad ECU.After a certain amount of time,it would act up.The only things that know time is the ECU and the fuel pump (heats up),however a fuel pump would not make the shift light come on and off.