Idle speed variable; due to temp?

[DarkNinja75]

When I start my car up in the morning the idle is around 1300 RPM's. Today, the car had been sitting in a parking lot for a few hours, and it was about 90 outside. I noticed that the idle was way down at 500 RPM's. Does temperature cause the idle speed to change? If so, how? And if not, what could be doing it?

[daniel2002p]

Yup when you cars engine is cold it will idle significatlly higher doe to the air/gas mixture, it is normal to have higher idle RPMs when the engine is cold...

D

[punter]

Yup, you have an Idle speed control valve. It bleeds extra air around the throttle body when you car is cold. Helps it warm up quicker.

Outside temp should have little to no effect on idle speed though.

[thespud]

Yah, the ISC Valve will be the one that will do it. Engine Temp plays a big part in Idle speed.

Sort of Off topic: Punter - do you know where the ISCV is on the 20v? I cant seem to track it down....

[punter]

You having Idle problems? The ISCV is under the TB's No.4 cylinder. Its a real pain to get to as the airbox + trumpets need to come off.

This photo is handy for 20v idle issues.

[thespud]

That is NOT what i wanted to hear Now i know why i cant find it.

But yeah, my idle is stuck at 1500-2000rpm, and all the vac lines are good, idle up works because if i reverse it and turn the ac on, it drops to a healthy 500, rather than going up to 1500, so all i can pinpoint is the ISCV...

[diver9000]

When I first dropped my 20v ST in my car it idled real high too. First few days the idle was about 1500. After a few days I replaced most of my vacuum lines. The idle dropped down to 1000-1100 and its been there since. That was 6 months ago. Now the only time it idles up is in the mornings when its cool outside. As it warms up the idle goes back to where its suppose to.

[thespud]

^^ I replaced ALL of the vac lines - they are good. So they are not the problem.

[punter]

From what I've heard ISCV is a pretty common failure, just need pulling off and cleaning.

[diver9000]

How do you clean it, and what symptoms are displayed when its bad?