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My neighbor has a grand prix that always has the hood up..I dont want to be a busy body but, his idle seems to be what is wrong with the car. When it starts it undulates at idle..it almost stalls then it catches and then it almost stalls...he still drives it so aparently once you get past idle the engine is ok.

I figure its a sensor..TPS or something..anybody have a comment..

Also I am not sure if its the 3.4 or the 3.8 but it looks late 90's vintage..

Any help I can give him??

Find out what engine. I know early 90's 3.1 in the W body required "learning" the IAC when the battery was disconnected. Not sure if that was the same for the 3.4L. Otherwise my guess is to check for a vacuum leak, TPS voltage, etc.

thanks..I figured vac leak or TPS...anyone know what the TPS should read if hooked to a meter? I'll do the search too but anyone know off the top of the head?

Well, if it's a late 90's GP, it'll either have a 3800 (S/C or N/A) or the 3100. 3400 was not an option in those cars.

3100's do have some history with vac lines breaking and MAP/MAS sensors going bad.

I'm new to the 3800 world, so I can't help you with that, sorry.

I do know that my '85 6000 with a 2.8 had an issue where it would idle like complete crap until it warmed up then it idled fine. The issue was a MAP sensor.

Krenzy wrote:Well, if it's a late 90's GP, it'll either have a 3800 (S/C or N/A) or the 3100. 3400 was not an option in those cars.

3100's do have some history with vac lines breaking and MAP/MAS sensors going bad.

I'm new to the 3800 world, so I can't help you with that, sorry.

I do know that my '85 6000 with a 2.8 had an issue where it would idle like complete crap until it warmed up then it idled fine. The issue was a MAP sensor.

I was talking about the pre-S/C GTP GP's with the 3.4L DOHC (X engine code). Not to be confused with the 3400 found in Grand Am's so on.

Ahh sorry. I thought you meant 97-03 style when you said late 90's.