2005 Chevy Impala Stalls when right after starting engine o

Tiny
CORYCLARK
  • MEMBER
  • 2005 CHEVROLET IMPALA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 164,000 MILES
Recently I purchased a used car so I haven't own this vehicle long. The car has run good up till this point. I started the car normally drove to the gas station. I shut the car off, fuel, started and drove 32 miles for for stopping. The car was idling fine when I came to a stop. I got out checked my trans. Fluid which was good listened to the engine and shut it off. Everything was going good until I went to start my car again. After about 4.5 hrs I went to start the car. It started and then stopped right away. The only way it would stay running is by giving it a little press on the accelerator when starting and keeping the RPM's up. I did have my cell phone charging while the car was off the whole time however the car did turn over fine. I drove the car 15 miles and all the way ever time I'd slow down it would want to die and I'd have to start it and give it a little gas. As long as I kept the RPM's up it ran good. What could this be?
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Wednesday, October 6th, 2010 AT 11:41 PM

7 Replies

Tiny
RENAUDTN
  • MEMBER
Is your check engine light on? If so go to your local autopart store and have them check the code(s); they do it for free usually.

I'd suspect low fuel pressure (clogged fuel filter?), Defective sensor (TPS sensor perhaps), weak ignition system, or vacuum leak.
Do you know if the car has ever had a tune-up?
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Friday, October 8th, 2010 AT 10:48 AM
Tiny
CORYCLARK
  • MEMBER
There is no check engine light on. The car runs fine as long as I control the idle. It doesn't take much to keep it running, it's more annoying because it will dye if I don't put my foot on the pedal to give it a little gas. It doesn't surge, hesitate, stall at highway speed. Only when the RPM goes to idle it doesn't level out.

Could the idle air valve motor be bad?
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Friday, October 8th, 2010 AT 11:25 AM
Tiny
RENAUDTN
  • MEMBER
Eventhough you don't have the check engine light on, you may still have a pending code stored. I'd check for that just to make sure.
A problem with your IAC will usually turn on a code P505 to 509. Here is a diagnostic procedure readily available online: The diagnostic procedure involves disconnecting ISC motor, then starting the engine to see if the idle speed increases (it should). Turn the engine off, reconnect IAC and start the engine again. This time the idle speed should return to normal. If it does, the problem is not in the IAC circuit or motor.
Keep in mind that a vacuum leak is a good possibility too.
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Friday, October 8th, 2010 AT 4:43 PM
Tiny
CORYCLARK
  • MEMBER
Here's something to throw you off. I did take apart the throttle body, well just the boot and sprayed throttle body cleaner in it. It was very dirty. I took out the IAC motor and clean it and in the port where it goes. It looked like the valve was all the way out, but I don't know if this is good or bad. I put it all back together, same result, won't idle. I disconnected the IAC motor as you suggested, no change. It was late so I quit fooling with it. Woke up this morning and same thing, won't idle. Made it the 45 miles to work o.K. And parked it for the 9 hrs at work. When I went to leave I started while I stuck my head out the window. I heard a small, wheeee sound like a little motor and it is now idling just fine. The wheee sound was like a little fuel pump in the engine compartment and didn't last long. I did hear the fuel pump too so I know it wasn't that. I did some other things tonight on it, flushed coolant (need it anyway), checked fluids, drove it. It is working good but makes me wonder what is wrong. I will get the codes checked and probably replace the IAC motor. I have a friend that his brother works at a chevy dealer so he can get me a part at his cost. Any other ideas!
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Friday, October 8th, 2010 AT 9:37 PM
Tiny
RENAUDTN
  • MEMBER
OK,
If your car works fine now that you cleaned the throttle and IAC, you may have fixed the problem.
However you can test the IAC valve and motor just to make sure:

Usually when you remove the motor and the idle air bypass solenoid (the nose in the video) is all the way out (meaning that the valve is completely closed), it means your engine has an air leak. Your car senses there's a lot of air coming in (thru the leak) and closes the IAC to prevent more air from getting sucked in thru the valve.
If your car works fine now though, it was just gunk in the throttle and you fixed the problem.
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Saturday, October 9th, 2010 AT 9:56 AM
Tiny
CORYCLARK
  • MEMBER
Thanks, you were a lot of help. I figured that is how the IAC worked. I didn't know about the sensor on the tip though. I think what was happening is that the motor was stuck closed and it wasn't letting any air in, that's why the car was dying and I can to step on the accelerator to keep it running. Now that the motor is work it's letting air in. I don't know if I should replace the motor anyway or consider it fixed. I found the part online for $50 but I do have a buddy who can get it for me from a dealer cheaper. I'll see how this goes, I just don't want to work on the car this winter in the cold if this happens! My luck it would be -40 F that day here in Minnesota! Thanks for your help.
What is your thoughts about replacing the motor anyway, should I buy one and get it done or is it fixed?
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Saturday, October 9th, 2010 AT 9:45 PM
Tiny
RENAUDTN
  • MEMBER
If you troubleshot the motor as explained in the video and everything checked out OK I wouldn't replace it. It's not uncommon for a high mileage car to have trouble at idle because of a dirty throttle and/or IAC valve. On top of that, if your IAC had failed completely you would have had a code (P0505-509), so if your car runs fine now with no code/pending code, you probably fix the problem. However, if you start sweating everytime you get behind the wheel because you're afraid your car is gonna act up again, maybe it's worth replacing it for peace of mind sake especially if you can get a good deal on it. Your call :)
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Monday, October 11th, 2010 AT 1:58 PM

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