malibu mystery

[paparker]

I have a 98 Malibu, which is showing some confusing symptoms.
1. When accelerating, the car has a loss of power, and hesitates through the acceleration. Upon stopping, placing the car in park and depressing the accelerator, the engine does not miss, running beautifully, so the problem exposes itself only when the engine is under load.

This problem has only happened in the middle of a day of errands, when the engine is already warm. If I let the car sit for a couple hours to cool off, it will start right up, no problems.

2. When attempting to start the car, the starter will turn the engine, but the engine does not start, exactly what you might hear if the engine was not getting fuel or spark. I have verified that the fuel pump is working, when this no-start situation is present.

This problem also only happens when the car is warm, and will go away when the car cools.

I believe the two problems are related, and am currently suspecting either the ignition module or the fuel pressure regulator. Does anyone have advice or experience in these two symptoms? I am currently looking for a way to test the function of the fuel pressure regulator. Any advice?
Thanks in advance!

-parker

[DaYtOnAt2]

My best educated guess would be the TPS as it is electrical and highly affected by heat. I have not had this same problem on my malibu but the exact same symptoms led me to replacing a relatives TPS on their 2000 explorer. I know it sounds unrelated but you'd be surprised...For what it's worth...

[wpbharry]

Will be curious to see what diagnosis you come up with. That, and several other problems (like the ignition lock cylinder having gone for the 7th or 8th time), led me to ditch my '98 LS in June for new wheels.

[paparker]

Thanks Daytonat2, for your advice. What is a TPS? My guess is throttle position sensor. Is this correct? If so, do you suggest any test I could do when I'm having the problem to diagnose the TPS?

Thanks!

I'll let everyone know my progress.

-parker

[DaYtOnAt2]

Unless you have a scanner there is really no way of knowing what the TPS is reading. What you were doing at the time it happened before is about the closest thing to field testing without a scanner. Yup,TPS=Throttle Position Sensor. Shouldn't be all that expensive and is really simple to replace with hand tools.

[muzikluver]

you may also want to check your air filter and IAT sensor conections