Cars idles alot better after heat soaking

[jefferson]

When my wife parks the car in the garage after getting home from work and then I leave in the car a little later the idle is way better on the car. I am thinking that it might pay dividends to insulate the iac so it would hold that heat in and maybe idle better all the time. Does this happen to anyone else as far as idling better after sitting hot?

Jeff

[Legacy777]

Jeff,

I think the idle issue may be a result of better air-fuel mixing, rather than anything to do with the IAC valve, due to the added heat. It may also have something to do with the fueling the ECU is calculating against the coolant temp sensor.

These cars are not necessarily known for their wonderful idle. How long does the car idle better after starting it up when it's been sitting?

[jefferson]

What makes me think it is the heat in the iac is that the idle will instantly go to 750 and even do it when you blip the throttle. It will always hang around 1100 for awhile and then drop to the correct idle except when it is heat soaked. It could very well be other things, but I think I will try the insulation thing just to see what it will do for me.

Jeff

[91Beater]

Mine experiences increased idle speed after warming up. Vacuum lines are rubber and the leak characteristics probably change with temperature.

[Legacy777]

Yeah....your description sounds like something else....like a vacuum leak or something sticking, and it takes the ECU & IAC valve a little bit of time to compensate.