Hi Idle

AV8R040

Registered User
I have been reading around on the board quite a bit and still haven't seen anything that really relates to this question. After I have my 90 SC warmed up it wants to idle up around 1200-1400 rpm on the tach. I have no other problems with the engine running but I definatly think this is a little high. I still need to clean the throttle plate but I wanted to see if anyone thought there might be something else causing this problem. Thanks
 
Hi-idle

Try replacing your IAC valve,located on the throttle body.get a Ford one,too many people have trouble with aftermarket ones.
 
I'd agree about the air bypass valve, but try cleaning it off first. Maybe it just needs a good cleaning. Try using...ahh, whats the name of that thing....its a spray that cleans electrical connections...thats all I remember. And simply use a rag to clean out the inside of the valve...if you can see that its too burned up inside, then it probably does need to be replaced. Costed me $81.85 from ford back in '99 when i replaced mine. Ford part# E9SZ-9F715-E...they call it "Valve Assmbly-Throttle", i guess they mean for the throttle body, since its located there. hope it helps.

luis
 
no noises just the high idle I will be cleaning it shortly if that is no help then I am sure I will be replaceing the thing. If I go to a 70mm throttle body does that have the new idle solenoid on it??
 
mine does the same thing

i was just reading the post and mine idles at 2000 rpm after i drive it for a while. when i turn the engine off it howles and kinda like whirles down. i just thought it was the sc whineding down is it some thing else. Bill
 
High idle is almost always a air leak somewhere. Air is leaking in after the engine computer has measured the amount of air. Thus more air than expected causes the idle to go high and a lean condition.

If you are hearing a whine after shutting down, I'd be looking at items after the supercharger. Check all of the bolts and nuts on the intercooler tubes. Check the big nut on the top. (I found two loose nuts on my IC tubes when I pulled them off for motor mounts)

The IAC is the idle air control solenoid. Our vehicles have their idle controled by the computer. It does this by metering in outside air into the engine. When the IAC fails, it tends to let too much air in or varies the air too much causing too high of an idle or unstable idle. You can try to clean the IAC but be carefull as there is an diaphram in the unit that can become ruptured. If that doesn't work you need to replace it.

It is possible that a failing IAC will throw a code, so you may want to check for engine codes to see if this verifies the diagnosis.
 
Well I cleaned the throttle body around the butterfly valve and now it idles perfectly at 800 rpms it was a bit dirty with some carbon buildup there. Thanks for the help and I will keep an eye on it if it happens again I will start checking the IAC vavle
 
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