Increasing RPM Idle
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Joined: Jan 2006
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Increasing RPM Idle
Have a 99 2.5 with 5 sp. When sitting at idle for a few minutes, the idle will increase all on it's own. I don't have a tach, but it seems like it increases 30-40% over normal idle. A quick tap on the throttle will raise the rpm of course, and it will return to normal for a while. Anyone have any ideas of where to look for this problem? TIA!
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New User
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This is the first I've heard of this being normal. As far as conditions - coolant level and temp gauge appear normal. It does this with A/C on or off. Again, if I am sitting in my driveway for a minute or two, the idle will increase all on it's own. As an example, this happens when I start, and go in the garage to get something - when I walk back to the truck, I am at "high idle". I "blip" the throttle with a quick tap, and the idle will return to normal <low> idle. Tiggie - is this normal??
Post Fiend
Joined: Jul 2005
Posts: 8,462
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From: Durant, OK (SOSU)
If you have a multimeter, you might want to prod the wires on the IAC (Idle Air Control valve) it's on the driver's side of the throttle body on my 4.0L, looks like a little cylinder. It can clog up at times and cause idle problems, but a random idle increase is new to me.
Does it gradually go up or just jump up to high idle?
Does it gradually go up or just jump up to high idle?
Laughing Gas
Joined: Jul 2002
Posts: 769
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From: Moneta, VA
From what I have experienced with mine, it isn't engine temperature related, but it seems to be based on a time interval.
My idle is normally 600rpm, and when the extended idle feature is activated, the rpm increases to about 850-900rpm. Not a huge difference, but noticeable.
It may not be normal, but mine does it so predictably, I can't beleive it is a malfuction of any type.
My idle is normally 600rpm, and when the extended idle feature is activated, the rpm increases to about 850-900rpm. Not a huge difference, but noticeable.
It may not be normal, but mine does it so predictably, I can't beleive it is a malfuction of any type.
