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Adam98SVT

Possible IAC failure?

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So recently the car started to idle ~2000 rpm and it took a long time to go from 5k to 2k.  And then when I am at a stop and its at 2k or 1500 I can stab the throttle and SOMETIMES it will drop down to under 1k.  Sometimes it would stay at 5k for a few seconds and just hang there before falling to 2k.

 

It seems to be getting progressively worse.  I drive about 50-100 miles a week.

 

Other than a funky IAC what else could be the problem?  Throttle cable?  I have to think about the throttle cable simply because it sometimes fixes the idle when I stab the throttle.  Under the hood the TB assembly and throttle cables operate normally by hand.  One of the cables is attached properly but is an inch or two longer than necessary so it doesnt engage until the TB is partially open.  It looks normal though, nothing looks damaged at least.

 

Motor is '04 3L out of a Sable IIRC.  Any help is greatly appreciated.

 

Thanks!

 

Adam

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Also there are times when I come to a stop and as I push in the clutch and drop the trans into neutral the RPM will actually rise a little and stay there, then drop a little.  Its very erratic but its always a problem.  It used to be where I would blip the throttle and that would take care of it but not any more.

Edited by Adam98SVT

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I would check 2 things. First, I would check for any bind in the throttle return spring.We lube them when we build them but lately the first gen throttle bodies have been getting "sticky" at the last 1/8" of travel (back to the throttle stop). Hit it with some PB Blaster and some good spray lithium and it should free up and act normal. Also, check the rear vacuum plenum. At times depending on the weather and heat there are 2 vacuum caps, and they can in certain conditions dry out and rot. This causes a vacuum leak the IAC can't control.

 

Those are the only 2 things I can think of...

 

-Dom

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