Mechanics

PERIODIC STALLS AT START

2004 Pontiac Grand Prix

My car sometimes stalls out when I start it. There is no rhyme or reason as to why or when this occurs. I took it to the dealership for inspection. The first time in the shop they removed and cleaned the injectors, flushed the fuel injectors and cleaned the throttle body and replaced the fuel filter. The problem persisted and then the check engine light went on. At the 2nd visit (within 2 weeks) they replaced the coolant temp sensor due to a DTC(PO128). Two weeks later the check engine light went on and I continue to have issues with the vehicle stalling when I start it up. I am now being told it is the ECM.

I feel like the dealership is guessing and just fixing one thing after another when the items they " correct" may not even be a problem. Any thoughts or comments?
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Dmyroup
February 19, 2007.




Is the light on now? If so have the codes checked again, a pcm can go bad, its electronic but rare on your year, the shop may not have looked hard enough for the problem and did all of the gravy work first,

lmk
thanks

Tiny
CHEVYII
Feb 19, 2007.
Just got back from the dealership (in a rental car). The PCM was replaced due to DTC 128 but the car did not start when I went to drive home from the dealership. The same issue as before. I crank the car, it sounds like it will start, but just as the MPH and RPM guage moves from 0 to max as it does with every start, the car quits. The only way I can get it to start is to pump the gas while I start the engine.

Any thoughts as to what should be explored next?

Tiny
Dmyroup
Feb 19, 2007.
The p0128 if for the temp sensor that was replaced, but there are several conditions that need to be met before the vehicle will start the ecm needs info from the iat intake air temp sensor, maf mass air flow sensor and the ect which was replaced, I know there was a problem with the iat connector that caused the same problem, I probably replaced 200 easy,
the iat reads incoming air temp, then the maf which is right behind it reads air flow and the ecm will adjust fuel accordingly, there are several other components but these are most likely, from what you have stated

i didnt think the ecm would fix it, that only means the problem is before the ecm (input signal needed to start)

keep me posted,
oh and I figure you been through it and know the lingo

Tiny
CHEVYII
Feb 19, 2007.
The dealership was never able to duplicate the stalling issue but they did find a DTC 2960. They determined that my second key was not learned. They reprogrammed the key and no issues so far. Seems strange that the key would cause the car to start and then stall out even though I could get the car to start by pumping the gas.
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Tiny
Dmyroup
Feb 25, 2007.
Well the key relearn is a simple repair they should not have charged you for that, but if the second key wasny programed the car wouldnt start? I wish you were here I would spend some time on this and find it, im checking my brain for a sec and will get right back to you, ok the theft deterrent module reads the keys signal and set the code you have above, I guess my whole problem is the car should not have run at all unless the key was learned , now if you were using the same key the whole time and driving the car? It realy makes no sense the code for the vtd module would have been there the first trip if the same key was used, confusing eh

let me know
jim

Tiny
CHEVYII
Feb 25, 2007.
I'm also having the same stalling issue. Sometimes it start ok and others I have to pump the gas to keep it started. I have taken it to the shop and they put an update on the pcm and that did help. I also have a second key but I don't use that much. I also ways use the key that came with the car. Any ideas on what it could be. The shop doesn't know and they just charged me for doing nothing. Could it be a sensor?

Tiny
Jquade
Jan 24, 2009.
Hi my 04 grand prix done that for two years start then stall. Untill I removed and thoughly cleaned the throttle body now it runs excellent and that was a few months back. Hope this helps

Tiny
Dwall1981
Nov 5, 2010.

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