LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

problem with the idle

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Old Mar 31, 2003 | 12:53 PM
  #1  
Tumbler96TA's Avatar
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From: King of Prussia
Question problem with the idle

I just got my first F-body on saturday, a 96 T/A M6. I was driving it today and it just stalled out on me. I noticed the second time it did it that the Idle dropped down to about 500rpm then tried to come back up and then just died. I was able to get back home without it doing it anymore by just giving it some gas at stoplights yet when i got it back home it seemed fine holding RPM's at about 800-900rpm. Any ideas what may have caused it?
Old Mar 31, 2003 | 01:16 PM
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95greendragon's Avatar
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Gremlins?
Old Mar 31, 2003 | 01:24 PM
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From: Hell was full so they sent me to NJ
The idle speed is programmed into the PCM, and for fully warmed up coolant, it is programmed for 800rpm in the M6's and 550rpm in gear/650rpm in neutral for the A4's. Remember the tach in these cars generally reads 100-200rpm higher than actual.

The PCM adjusts the Idle Air Control (IAC) motor, in the baseplate of the throttle body to control the idle. If the IAC valve or the air passages leading to it are dirty, you can have problems with idle. There are a number of other potential causes, but checking the IAC motor "counts" with a scanner would tell you if the system is set up and working properly.
Old Mar 31, 2003 | 01:57 PM
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From: Bentonville, AR
Injuneer hit it on the head
I had much the same prolems as you and after replacing the IAC, the car runs great....
Pull the Throttle body (Very easy!) Get some Throttle body cleaner and a new Throttle body gasket from a local parts store. And get to work with a rag and some q-tips
Old Mar 31, 2003 | 02:42 PM
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Since you just got it, it could be that someone had recently reset the computer and it had not relearned enough for stable idling. The more it idles the better it will get, so that could explain why it was better by the time you got home.

If it continues to act up, then I would suspect an IAC problem or even a vacuum leak.
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