but when i plug it back in the cars idle surges 1k-1500 any thoughts?

 

uhh....i would think that you need a new one...but lets wait for more anwsers....

 

yep you need a new one

 

My 93 prelude SI has the exact same problem. I have already tried another used but supposedly good IACV and it didn't make any difference. After the car warms up, the problem seems to go away.

 

jiltyndall my issue is vise versa my issue is after it warms up.

 

no I would not drive around with the iacv unplugged - try adjusting the idle screw above or below the tb ( i think it is above) flathead screw -it usually does the trick if that does not work then check for vacuum leaks this can be done by removing the intake then place you re figure over the 7 o'clock or 9 o'clock hole if the idle goes to normal then it is either a vacuum leak or an idle valve control problem last but not least use the search feature .....

 

you didnt to the bypass mod btw did you? because i have it done and i had to put some foil on the valce under the throttle body cause it started to idle funny when it started to get cold.

 

no i didnt mod the FACV.

 

its your FITV. Here is how you test to see if you Fast Idle Thermo Valve still works.

This test needs to be done with the car COLD.

Pull off you intake arm. Inside the throttle body on the Firewall side there should be a very small hole. Start the car, Put your finger close to/over the hole. Is their air flowing out of it ??? If not, its done. If so, its something else.

If you have a bad FITV the only symptom is surging idle until the car comes to operating temp.

 

no i think you guys are getting me mixed up or i posted it wrong. The car idles fine when cold it doesnt surge until the car is @ operating temp.

 

lol, the guy who posted his problem threw me off. If your IACV were bad, it would throw a code FOR SURE.

Pull it off, spray some carb cleaner in the screen to clean it up a bit, reinstall.
Also, check your EGR, it may be sticking or something. If that is really choked up with carbon, would probably have the same effect.

Im going to do some research and then repost for you.

EDIT: sounds like the IACV is the problem. Clean it or swap it with a known good one, reset ECU and start it up.

 

Kinda off topic but I put a block of plate for my iavc and left it plugged in. It made my idle perfect. I was wondering if this has any affect on the motor like causing it to run rich or something. All i know is after doing this my idle sits exactly at 700.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98TypeSH &raquo;</TD></TR><TR><TD CLASS="quote">This test needs to be done with the car COLD.

Pull off you intake arm. Inside the throttle body on the Firewall side there should be a very small hole. Start the car, Put your finger close to/over the hole. Is their air flowing out of it ??? If not, its done. If so, its something else.</TD></TR></TABLE>

You are right if the valve (wax bead) does not open, but most Fast idle valves stay open (they get lazy), which allows air pass the TB (like a vacuum leak), causing the engine to surge.

You test the Fast idle valve when the warm. Take off the intake arm and place your finger (with the car running) over the bottom left hole in the TB. If it is open (you feel sucking and the idle goes back to normal), The valve is bad. You can adjust it by pulling the cover and adjusting the valve, but you should replace it.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by matix &raquo;</TD></TR><TR><TD CLASS="quote">Kinda off topic but I put a block of plate for my iavc and left it plugged in. It made my idle perfect. I was wondering if this has any affect on the motor like causing it to run rich or something. All i know is after doing this my idle sits exactly at 700. </TD></TR></TABLE>

The IACV is valve that lets air bypass the TB. That allows the ECU to control the idle. The ECU gets signal(s) from load detectors (electric, PS, A/C). When the signal tells the ECU that those loads are being used. The ECU lets more air in (VIA the IACV) to keep the idle at what it wants.

 

i got ahold of the guy i gave the h23 stuff to from my old motor im gonna swap my h23 IACV and FACV and EGR i know they work so this should fix my issue i hope.