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3.9 idling waaay too high

2614 Views 4 Replies 4 Participants Last post by  TerryS
My 3.9 manual has been idling recently at around 2400rpm. It seems to occur at random from start up, either on gas or on petrol.
Sometimes it will drop in stages back down to normal if I get stuck at a red light for a long time, but mostly it just continues idling high.
This is not too good around town, but a real pain on muddy down hill descents.
Any clues?

1 - 1 of 5 Posts
Sounds like you need to reset you base idle speed. Not real complicated.
First thing, clean the IACV.
1.Start the engine.
2.Pinch off the hose between the IACV and the throttle body, using a pair of needle nosed vise grip or other clamp pliers.
It's important that you completely close off this hose.
3.Disconnect the IACV plug

4. adjust the base idle set screw on top of the throttle body to 600-650 rpm
5. shut of engine, and disconnect battery for a minute or two.
6. Reconnect IACV plug, remove vise grips, reconnect battery and restart.
1 - 1 of 5 Posts
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