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1992 Merc 3.8L V6

grandspan's Avatar

Join Date: Jul 2002
Posts: 182

08-06-03, 08:18 PM   #1  
1992 Merc 3.8L V6

1992 Merc Cougar 3.8L V6 with very low miles 41,000
My original post of July 11, concerning the engine not slowing down when you let off the accelerator:
I tested the resistance of the IAC motor with a digital VOM and it was within specs. I researched the Professional Mechanics Online website and found several horror stories of people having paid to replace one or two IAC motors as well as the engine management computer, and ending up with the same problem.
I unplugged the wiring harnes from the IAC motor and found that the engine idles down. So I then turned the idle screw to bring the idle speed up to specs and the car is running fine (with IAC disconnected) for about the past three weeks, it slows down fine and runs normal and the "Check Engine" light is not coming on, so I'm leaving it this way. It's definitely not a "by the book" fix, but it works.

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08-06-03, 09:08 PM   #2  
you can't argue with success!

that's probably what i would have done, the only thing is it might idle a little rough with the a/c on, it needs that little iac kick.

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08-07-03, 03:40 AM   #3  
Ok, lol.

Maybe it was futzed with before you got the vehicle, who knows???

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