wildazme

I recently replaced my Idle Air Control valve on my 98 gt and now sometimes when i start the car my idle rpms jump up to about 1500 or 150 whatever halfway above the 1 is and just hang there and when i take the car out of gear it jumps because its idling so high. the car used to jump up to the 1 when first started but then would fall down to about halfway between the zero and one. Any ideas what could be causing this?

monkeydude3

do you give it a few seconds to run and let it calm down? I have a manual but mine idles at 1500 then drops down.

or does it stay like this even when hot?

wildazme

it stays like this even when hot, it doesnt do it always only occasionally. sometimes i can drive the car a few miles, turn it off then restart it a few minutes later and it just hangs like that.

monkeydude3

hmm... where did you get the iac? try tapping it when it's idling fast [&:][&:]

red2k1gt

Im having the same problem after i installed my tb/plenum and havent really figured it out yet either. Hopefully this thread will help the both of us.

wildazme

its a napa iac valve cost me about 80$.

monkeydude3

try disconnecting the battery and let the computer relearn it's got fresh air flow coming in

tcuallstar

for those of you with aftermarket t/b and pleniums, do your rpms hang really long when you have the a/c on?

In2dreamingbig

Sometimes CAI filter oil can coat the sensors and cause issues with idle. The IAC can be cleaned, in some cases. Also check voltage at IAC should be 12-14 vdc.