When the car is cold and I'm just sitting there idling the revs will slowly move from 1k to 2k, getting slower as the car warms. When the car is hot it doesn't happen. Any ideas? Seems like something simple.

 

yes it's something simple.

take off your IACV, and clean it with carb/brake cleaner then put her back on

 

thanks, i'll try that tomorrow.

 

let me know if this works out cause i have the same problem. It may have something to do with my obd2-obd1 conversion.

 

I've cleaned my IACV after replacing with a known-good piece and the car sort-of does this...

It idles fine until it's reaching the warm zone, and then the revs will bounce from 700-1000 repeatedly and slowly until it's fully warmed up. I don't think it's the IACV in my case unless I did a bad cleaning job somehow

 

ya i thought it was for warming up the motor but im not sure, my ls does it too

 

If that does not work either, then try taking off the plate on the bottom part of the throttle body, and tightening the fast idle screw. The screw most likely vibrated loose and causes that if it's not the IACV.

HTH.

 

waiting for the car to cool down, been running around getting tags, inspections, etc. i'll try it later in the day and let y'all know.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by poison &raquo;</TD></TR><TR><TD CLASS="quote">If that does not work either, then try taking off the plate on the bottom part of the throttle body, and tightening the fast idle screw. The screw most likely vibrated loose and causes that if it's not the IACV.

HTH.</TD></TR></TABLE>
I agree, the first thing I would check is the FITV... If not that then it could be something electronic but i doubt it (TPS voltage over 0.45vdc at idle, bad oxygen sensor, etc.) Good Luck

 

Bah, went out to do it, was missing my 12mm wrench. Then it started to rain... what luck. I'll be doing it tomorrow.

 

2 bolts to get the IACV off, took the rubber gasket out (didnt want brake cleaner on it), sprayed some brake cleaner on a shop towel, rubbed the filter/grille with the shop towel, car idles perfectly!

 

Good to hear!!!

 

my b16a2 swap in a cx is doing the same thing,it might be that i'm running a auto p28 ecu

 

My friend Mike (jdmDXrex) is running an auto P28 on his '88 Rex via a nonOBD-OBD1 jumper that I made... His idle had been acting up ever since we swapped heads and went OBD1... I hadn't really gotten any time to take a close look at what was making the revs bounce but last night I finally got a chance to change the auto/manual selection to straight manual... Well I did that and now the car idles perfect so it wasn't any problem in my jumper or oxygen sensor wiring as I suspected... All you have to do is open up the ECU... desolder out the RP17 and RP18 resistors then put a jumper in for RP18... If you are unsure of where RP17/18 are look right next to your ROM you'll also see (RP3/4/5/6/7/8/13/14)... If you need anything else let me know... Peace