low idle
Thread Starter
Instructor
Joined: Aug 2004
Posts: 111
Likes: 0
From: Wentzville MO
low idle
About a week ago my 80,000 miles 92 six speed began idling about 400 rpm when I first start it in the morning but is fine at 700 a mile down the road when I stop. Not a big deal unless it dies. Any ideas?
Thanks
Thanks
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
IAC isnt a sensor, its more like a valve. Its in the base of the throttle body and controls the idle speed of the engine. It could be sticking by the sound of it. Pull the throttle body off and clean it thoroughly, and also clean the IAC path. If that doesnt fix the problem then look at replacing the IAC, but also check the TPS voltage to make sure its not playing up when its cold (however unlikely that is)
Pro
Joined: Sep 2006
Posts: 702
Likes: 2
From: Conyers Ga
Originally Posted by Casethecorvetteman
IAC isnt a sensor, its more like a valve. Its in the base of the throttle body and controls the idle speed of the engine. It could be sticking by the sound of it. Pull the throttle body off and clean it thoroughly, and also clean the IAC path. If that doesnt fix the problem then look at replacing the IAC, but also check the TPS voltage to make sure its not playing up when its cold (however unlikely that is)
I'd also give the throttle body a good cleaning. Especially if you don't know when it was last done.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Checking the IAC stepper motor and IAC passages in the throttle body is always a good idea. However, the fact that it idles properly at 700 rpm, warm, suggests to me that the IAC is capable of passing sufficient air. A cold engine should have a faster idle than a hot engine, reminiscent of the olden days with a choke. I would take some Ohm readings from ECT sensor, at different coolant temps, and compare them to my FSM, to verify the the ECT sensor is operating properly. The ECM cannot establish the correct idle speed for the engine temp, if it doesn't know the engine temp.
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