I bought a iac valve not too long ago and for some odd reason my idle doesn't back down from 1800 quickly enough for what I would like it to do, like when the truck starts up I would like it to go up to 1,000 maybe 1200rpms and back down to 800-950ish? I can put on the old iac control valve and the truck will idle fine, what is the deal, could it be a defective idle air control valve from the box? There is no air leaks or anything either where the iac mounts to, the gasket is in primo shape. Thanks for any help...

Jason

 

anybody know?

 

The new valve is probably just working correctly . If you haven't done so, I would disconnect the battery to reset the computer. The computer has probably adjusted to operating a dirty/sticking valve, so with a new one, it holds it open farther than necessary.