Pontiac Grand Prix Forums : Grandprix

I have a 1999 Grand Prix GTP. When the engine is cold the car starts up perfectly. It will keep a solid idle, but when the engine warms up it cuts off. I've changed the fuel pump, fuel pump resistor, the battery, and the fuel filter. When I scan it for codes nothing comes up. I also checked for a vacuum leak, but there doesnt seem to be any. Could this be a bad crankshaft position sensor, throttle position sensor or camshaft position sensor? Or is it something else? Any ideas would be greatly appreciated.

Thank you in advance

i had a chevy blazer that did the same thing... would run great until it hit operating temp then it would bog down and shut off... no codes.. i was told it was the spider intake.. never followed up on it.. parted it out.

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Thrasher intake, Headers, Flowmaster 40's, F body brakes, slotted rotors, GMPP kit, 20 in Velocity 925's, Premier deck, Memphis highs and mids, Memphis amps, 2 DD 1510 subs.... 3.4 and tune on the way.

I have a 97 gtp I changed what you did including cranckshaft sensor. it runs only if I tap the throttle. i also have no codes. thanks all info helpfull

Before you changed the crankshaft position sensor was your GTP acting up like mine? Also, aside from having to tap the throttle, after changing everything, does it run fine?

hmm...a spider intake. I'm not sure if I've ever heard of that, what is that exactly?

they dont have them on GP's ... i was just throwing that out there.

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Thrasher intake, Headers, Flowmaster 40's, F body brakes, slotted rotors, GMPP kit, 20 in Velocity 925's, Premier deck, Memphis highs and mids, Memphis amps, 2 DD 1510 subs.... 3.4 and tune on the way.

the car still won`t run. I still have to tap the throttle to keep it running.

anyone try the IAC?

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what`s that

idler air control valve.

Basically controls the amount of air coming in the engine at idle.

It sounds like its failing when the throttle body warms up.

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I had taken that off to check.It had alot of carbon on it.I sprayed pb blaster to clean it up. I was tried to move it in and out. Got it to move in when I tried to pull out I pulled it apart. Now i need a new one now

Sorry, you did that say just now or you did that before?

And call up your local wrecker and see how much it is for one.

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I was going to the bone yard to get a maf, tps,and iac. I was just playing to see if I could get anything to work while taking them off. Was not planning on breaking it . I have a bone yard down the street. it would have to be one of these??????????

Is it possible that it could be bad ignition module?

Took it to a mechanic...turns out it was the mass air flow sensor!

Went to bone yard today. All 3.8 had missing mafs. must be a common problem with that being the only sensor taken off engines. I still don`t have a check engine light on. will try tomorrow at other yard. to see if they have one, if not I will bring it to a garage

For future reference, from what I hear:

common MAF diagnostic test is to disconnect it and see if the problem persists or stops.

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found problem.... fuel pump resistor. my brother found a link on this site,that had a car with same problem. it had a test to jump resistor to check. the post even told of a recall they have with the grand prix. I just can`t find the resistor. thanks for all the help jim