Idle speed too high?
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New User
Joined: Jun 2005
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From: Orange, CA
Idle speed too high?
Hey all. I have a 99 3.0L 4X4 with about 81k miles on it. It idles at about 1,000-1,100 RPM (when warm, cold, with AC, with out AC, etc.). I got the truck from my Father (RIP 
) a couple months ago and it was like that. I'm guessing this is too high, as my '02 (with the same engine) idles at ~6-700 RPM. What should I check, just use starter fluid and start looking for a vaccuum leak, or is there something more complicated than that I should be looking for? Thanks in advance! 
-Brian
) a couple months ago and it was like that. I'm guessing this is too high, as my '02 (with the same engine) idles at ~6-700 RPM. What should I check, just use starter fluid and start looking for a vaccuum leak, or is there something more complicated than that I should be looking for? Thanks in advance! -Brian
Fleet Owner
Joined: Mar 2003
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From: Blue Hill Township
Nope, what you're gonna want to do is first clean all the sensors. Clean the MAF with electrical cleaner, as well as the IAT. Then, clean out the throttle body with throttle body cleaner, not carb cleaner. Throttle bodies have a coating, and the cleaner must specifically say that it is for throttle bodies. Also clean the IAC (Idle Air Control) with the throttle body cleaner, and then see how she idles.
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From: Orange, CA
Originally Posted by mistercmk
Nope, what you're gonna want to do is first clean all the sensors. Clean the MAF with electrical cleaner, as well as the IAT. Then, clean out the throttle body with throttle body cleaner, not carb cleaner. Throttle bodies have a coating, and the cleaner must specifically say that it is for throttle bodies. Also clean the IAC (Idle Air Control) with the throttle body cleaner, and then see how she idles.
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Joined: Jan 2004
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From: SW Va
Add checking for vacuum leaks to the list.
This includes all accessores that use vacuum. Their fittings, line splices & the vacuum lines as well.
Look for dryrot or signs thereof, like splits, cracks, cuts, loose fitting vacuum hoses on connectors & chafed hoses, especially where they are in close proximity to something hot, touch, rub, vibrate against, or pass through something & along bends, especially the outside radius of a bend.
As has been said, make sure the throttle plate, it's outside diameter edge & the inside of it's operating bore, is clean & free of deposits that could cause the plate to hang up & not to fully close.
Then check the throttle cable & it's attached controls for any binding condition that would prevent it from closing completely.
While your there, also check the IAC, throttle position sensor & it's mounting hardware, electrical connectors & vacuum connections.
Let us know what you find.
This includes all accessores that use vacuum. Their fittings, line splices & the vacuum lines as well.
Look for dryrot or signs thereof, like splits, cracks, cuts, loose fitting vacuum hoses on connectors & chafed hoses, especially where they are in close proximity to something hot, touch, rub, vibrate against, or pass through something & along bends, especially the outside radius of a bend.
As has been said, make sure the throttle plate, it's outside diameter edge & the inside of it's operating bore, is clean & free of deposits that could cause the plate to hang up & not to fully close.
Then check the throttle cable & it's attached controls for any binding condition that would prevent it from closing completely.
While your there, also check the IAC, throttle position sensor & it's mounting hardware, electrical connectors & vacuum connections.
Let us know what you find.
Last edited by pawpaw; Oct 11, 2005 at 01:54 PM. Reason: correct spelling
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Joined: Nov 2004
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From: Ventura ,ca. (near L.A.)
FYI, My 02' with a 5spd idles at about 800-900 RPM when cold, 600-700 at normal operating temp and 1,000-1,100 rpm when it's hot outside and i'm stuck in traffic. It also idles around 1,100 if your in neutral going down the highway, like 65mph. My truck has been like that since it was new. I think it idles faster when it's hot outside to spin the water pump and fan faster for better cooling.
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