99 Explorer, 4.0 SOHC, auto trans. Engine starts and runs fine, but after it warms up the idle speed jumps around from 900 rpm to as high as 1500 rpm whether in gear or not. Can anyone help with what the problem might be and how to fix it. Thanks, Dennis
fluxuating idle speed
Apr 25, 2006
7 Replies
Vacuum leak ??? and/or Leaking intake gaskets ??? and/or Binding iac valve ???
C.E.L. on ???????? any codes ???????
If no codes its usually dirt related, dirty t-body and /or iac valve
The problem just started suddenly about 5 days ago. I don't have any code info or know where to start troubleshooting to see if its a vacuum problem or something else. I also don't know what an IAC is or where the IAC is located on the engine. Any further help would be greatly appreciated.
IAC = idle air control .I forget EXACTLY where it is on the throttle body. It controls the idle speed.
The IAC was replaced last December by my Ford dealer. Could the new one now be going bad or should I being looking elsewhere for the problem?
Is the CHECK ENGINE light on ?????
If so, goto pepboys and have the codes read, they do it for free but don't buy anything !!!!!!!
There are no dash warning lights that come on when this happens...
As stated before, no lights then its usually dirt related, clean t-body and air idle control valve with t-body cleaner
You might have to soak the iac valve
Just GOOGLE it, for instructions
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