This has bothered me ever since I first bought the Explorer last year. (It's a 2000 with the 4.0 OHV engine). When it's initially started, the revs go to 1800 and then slowly drop down to normal. This happens every time it's started, regardless of the outside temp or whether the engine's hot or cold. This seems like an excessive fast idle to me.

I've changed the IAC, cleaned the throttle body, checked throttle stop adjustment, checked for vacuum leaks, reset PCM, etc, etc. Nothing has changed; it still goes to 1800 rpm when started. There's no MIL, and the Explorer runs fine.

What does everyone else's start at? Maybe this is normal.....???
Thanks.
Don

 

I don't have one but tha is normal. When the vehicle is shut off, the iac goes to a "set" point so that the comp knows where it is. After the vehicle is started, the comp looks at the data and lowers it to where it is supposed to be.

 

Thanks for the reply, Stepman. What you say makes sense. I have an extra IAC that I'm going to experiment on; maybe by restricting the valve opening when the engine is shut off. I'll post the results if anything works.