Hi all, sure hope someone can point me in the right direction.
My Taurus GL, 3.0L auto runs great, when its happy, but lately what I
am having is really high idle speeds after driving it for a while.
Start it up, drive a bit till its warm, and it idles as expected. Keep
driving, and sooner or later, within ten minutes or so, when I get to
a traffic light or whatever, the engine doesn't idle down to normal,
but hangs way up there, like maybe closing in on 2000 rpm. (hard to
guess) Makes life really interesting when I try to stop it :-)
I pull over, pop the hood, and try to force the throttle closed as a
test, but it is closed all the way, no doubt about it.
Turn off the engine, and then start it back up, and its idling
normally again. Sometimes it will repeat after a while, other times,
it runs fine.
I have cleaned the throttle area to make sure no gunk is hanging
things up, and even used a toothbrush on the inside of the throttle
body around the blade. The cable is not binding.
I am not at all familiar with how the computer controls the engine
speed beyond the throttle position sensor and am thinking the idle air
control valve, but everything I have read, tells me the IAC will cause
low idle speeds, not very high ones. I was told that if I unplug the
IAC, and the engine stalls, its probably working okay, but perhaps
that is a faulty statement?
I have a shop manual, but the idle control ckt is apparently
addressed in the emissions control manual, which I cannot find for
less than $275, so I am hoping someone might have an understanding of
what controls what, and where I should be looking? Odd that turning
the car off and then restarting "fixes" the problem, so I am thinking
electrical, somewhere, but not sure where.
There is no check engine light, and no trouble codes when I have it
Any advice would be appreciated,