2004 Grand Prix won't stay running


#1

The engine cranks and turns over when I turn the key, but won’t stay running unless I give it some gas. My mechanic doesn’t know what’s wrong with it, but I haven’t starting having him replace parts until I have a better idea of what’s going wrong. Could it be the fuel filter? fuel pump?


#2

If you can rev it normally, it sounds like the idle air control valve needs to be cleaned or replaced.


#3

Your vehicle doesn’t have an Idle Air Control valve. The idle is controlled by the drive-by-wire throttle body.

http://www.rockauto.com/catalog/moreinfo.php?pk=3763986&cc=1429703

When the ignition is turned on, the motor on the throttle body slightly opens the throttle plate. This allows idle air into the engine. If the motor fails to open the throttle plate the engine won’t idle.

When you step on the accelerator, the accelerator pedal position sensor commands the computer to open the throttle plate and the engine runs.

You can check for this by removing the intake hose from the throttle body, turn the ignition on and see if the throttle plate slightly opens.

Tester


#4

This brings up a good point. I didn’t look around enough and relied on one source:

http://www.nextdayauto.com/2004-pontiac-grand-prix-fuel-injection-idle-air-control-valve-delphi-w0133-1683286.html

I have to agree that RockAuto.com is probably the best source for this information. It, of course, had no listing for this IAC valve on this model.


#5

Why are you coming up with a diagnostic strategy for the car? That’s the mechanic’s job.

What testing has he done to try to determine the cause?

I’m guessing a competent mechanic with a decent bi-directional scan tool can diagnose this from the driver’s seat without even opening the hood.

There are too many options as to what’s wrong for us to get you headed in the right direction without more information.


#6

“Why are you coming up with a diagnostic strategy for the car? That’s the mechanic’s job.”

So you feel that every answer to repair queries on this site should be: “Take it to a mechanic.”? (Actually, that’s technically not a bad idea, but it would make for pretty boring reading.)


#7

“Why are you coming up with a diagnostic strategy for the car? That’s the mechanic’s job.”

I agree

I don’t really appreciate it when I’m trying to diagnose something, and the customer has his own ideas about diagnostic strategy

That’s my job

If the customer is so smart, he should go to school, buy a tool box, tools, a scan tool, etc. and have at it

When I go to see my doctor, I tell him my symptoms. He figures out what’s wrong with me. Why should it be the other way around?

Lately, it seems that every car owner that’s ever changed his oil, rotated his tires or did a pad slap thinks he can diagnose and repair cars just as well or better than the pros who do it day in and day out.

This is a free country, last time I looked

They’re free to think that way, and talk smack if they want to

But that doesn’t mean they’re correct


#8

“So you feel that every answer to repair queries on this site should be: “Take it to a mechanic.”?”

No. In this case the car is already at the mechanic and he’s simply not doing the job, as least according to what the original poster is saying. Either that or the OP is not letting him do the job as he sees fit.

@t1m8omatas, please give us a little more info, like what your mechanic said the problem might be, and then we can help you get in the right direction.


#9

Check fuel pressure.


#10

Stalling is a known issue with the Grand Prix 3.8L V6, due either to a bad mass airflow sensor (MAF) or bad crankshaft position sensor (CKP).