99 SE 5 speed with 53K miles... I have a problem with my idle speed being erratic, especially when cold. I first noticed a very high idle speed on initial startup (about 1800-2000 RPM), but it did slowly drop as the car warmed. Then when fully warmed, the idle would drop very low (400 RPM) every time I would push in the clutch, but then recover to about 600, slightly rough. I read all the helpful posts about cleaning the IAC valve and the TB, and I did that. The IAC was pretty dirty... After reassembling, I still have the very high idle when cold, but the problem (when warmed up) of dropping very low and then recovering is gone. So I seem to have done some good... Any tips on how to attack the high idle when cold? Should I disconnect the battery for awhile (maybe the computer needs to relearn something?). Also, my Haynes manual has what I think? is a typo, maybe someone could confirm. There is a 6 pin connector on the IAC valve, and the manual says to look for ~30 ohms between the following pairs of pins (1-2, 2-3, 3-4, 5-6). In my case, all the readings are OK except I get an open for 3-4, and 30 ohms for 4-5 (which is not in the manual). Is the 3-4 in the manual a typo that should read 4-5? Or maybe that is my problem? Thanks.....

 

Try cleaning your throttle body? I finally got off my ***(damn this forum) and cleaned my throttle body. It wasnt that dirty, but I was still amazed how much gunk I got out. It idles a tad bit better and got some decent throttle response. But everyone kept saying "clean your throttle body" so I did.

I used STB carburator cleaner.

 

High idle when cold is normal. 1800 - 2K sounds ok, does it drop to around 1500 within a minute and then slowly work it's way down as your engine gets up to normal opertaing temp??

If so, there's nothing wrong with your car.

Enjoy the ride....

 

I'll have to check it tonight... I think it idles at 1800-2000 for more like 3-4 mins, but I'll have to time it. I know it is different than the way it used to be 'my normal', enough so that I notice it when I first drive away after startup (car kind of drives itself without me pressing the gas pedal, a little scary with snow on the road).... I think I will also do the adjustment procedure for the idle speed with the TPS disconnected, just to be sure the baseline is OK, especially since I just cleaned out the IAC and TB.... More to follow....

 

Well, I adjusted the idle speed, and also sprayed some lube on the cables and mechanical things, and now it seems to be approaching normal... It does seem like the computer is relearning things as I drive, so hopefully in a week or so things will be AOK.