Idle problem for 4 years!! HELP!!!

emagdnim

Active Member
Feb 5, 2003
391
15
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Hello , My car is a 1988 speed density..
My car is running great now after tuning it up just it idles @ 1400 rpm without the IAC connected... With that connected it even idles higher when it opens up. Ive checked the hoses for vacc leaks but they all seem ok.. Ive replaced the tps sensor (set it to 0.99v) , Replaced the EGR (old one was plugged up..) , replaced the pcv valve but it still idles like a crazy mofo... Ive taken off my long tube headers and xpipe and put everything back to stock because i plan on doing a h/c/i swap this summer but i want the car running perfect before i start doing that to avoid future problems. Could something like a Temp sensor cause the fast idle or does it basically come down to some kinda vacc leak that im overlooking? Ive sprayed carb cleaner around the hoses and it didnt make a difference and ive listened closely for leaks . Any suggestions this is something i cant seem to fix.
 
what is the vac reading at idle? it should be real close to 20" hg at idle (for me, 700 rpm). any codes?

has the idle been set or messed with recently? here is a decent write up on setting the idle:

http://www.muscularmustangs.com/iac.php

the car should idle (warm motor, no load) on its own without the IAC, and it should be near 700 rpm if you have a stock cam.

good luck.