Mechanics

I INSTALLED A NEW IAC VALVE, AND NOW MY IDLE SPEED IS A LITTLE ERRATIC.

2003 Chevrolet Silverado • 148,000 miles

I've driven the truck twice since installing the new IAC valve. The first time, it started to idle erratically. Going up as high as almost 2000 for a couple seconds one maybe one or two occasions, and almost low enough to bog out on another couple occasions, but mostly stayed between normal idle speed and about id say 1200. The second time I drove it, it didnt do it but I only ran to the gas station and back. A couple details, I was installing the IAC valve in the throttle body, which was out for cleaning, and I over torqued a screw and broke it in the throttle body. Went to the junkyard and got another one, inspected it, mounting surface was good, no scratches, but the cleaner ran through the flap a little while I was cleaning it. This didnt happen on my original throttle body. Also I replaced the gasket. The old gasket was blut, and a consistent thickness all the way around, and thick enough to fill the entire groove for the gasket. The new gasket made me a little suspicious. It was red, and it was the right basic shape, but it was not as thick as the blue one, but it had little bumps like every I dunno half inch or so, which made it fit snugly in the gasket space. I installed the valve following my haynes manual, which gave no instruction for using evoscan or ecuflash, but I read a thread earlier (the only similar problem I could find was a mitsubishi) that suggested using those. I dont know what they are or how to use them. I DID make sure the pintle of the valve was no more than 1 1/8 inch away from the mounting flange. I think I read last week somewhere that these things just need time to readjust themselves? I dunno. Can anyone help me?
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Run the truck several more times to see if the computer recognizes the new IAC and starts working properly.

It seems to be doing good now. Thank you!

I had the same issue. I replaced IAC sensor and TPS sensor and now after running it to allow computer to reprogram itself, my truck bogs out when returning to park after driving vehicle. Is there anything I missed during this repair
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Tiny
Bsteele2113
Aug 3, 2012.

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