I have an '89 Buick Century, AT, with a 3.3l engine that wants to stall at stops, and "bucks" as you drive it uphill. Lower reading than normal on voltmeter and "Check Engine" indicator light comes on every so often. Sometimes I need to keep my foot on the accelerator at stops to keep the engine running. Had a similar problem twice before, one time it required replacing the IAC valve, the other time, a new ECM (computer). I’d like to do the repair myself this time, but am wondering how to determine which device is causing the problem – the IAC or the ECM. I’ve been told the ECM cannot be returned once I purchase it, not sure of the return policy on the IAC. Is my best bet to first remove the IAC, clean it thoroughly, and see if that fixes the problem.Any thoughts? Thanks.[img]smileys/smiley2.gif[/img]

 

Cleaned up the IAC valve, reinstalled - still have the problem. How can I test the IAC to verify it is working? Would a bad IAC valve cause the "bucking" and hesitation I'm experiencing while the vehicle is moving (40mph or so), or like the name states, does it merely regulate engine speed while idling?


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