high idle

[tonydi]

Hello: my 2000 explorer 4.0 sohc sport idles around 1200 rpm used to be about 600 rpm.The iac is working. when disconnected the truck dies is this normal?, checked for vacuum leaks none found. any ideas?...tony

 

[gijoecam]

My best guess is the lower intake manifold seals, but I can't say for sure. Is the throttle body plate sticking partly open? Maybe the cable is binding a bit preventing it from returning to the full closed position....

My best guesses. :dunno

-Joe

 

[tonydi]

fixed it. the problem was with them thermostat , sticking closed explains the high idle problem.Being here in buffalo ,ny the gauge never really went to full hot.swapped it out now idle is about 600 in drive.easy fix....tony

 

[budwich]

glad you fixed it but confused???? ... " sticking closed"... this would cause you gauge to go full hot fast!!!! as opposed to never. I think perhaps you meant fully open which would keep your engine and temp sensor cold which then would keep your idle high as your computer "thinks" your vehicle is in "cold / initial start" idle.

 

[tonydi]

Its been very cold here lately.Didn't drive the truck around long enough to get really hot.Yesterday went to the dealer to pick up a thermostat it went right to hot after about 10 minutes of driving,then dropped to half way and start the cycle over again.This morning went over to a friends place to do the stat and the truck overheated check gauge light went on.When i removed the old stat it was stuck closed(still very hot coolant).After the new one went in it idled were it was suppose to be. I believe the truck was running the idle a little high to cool off the engine with the fan....tony

 

[budwich]

I don't think the system is set to "speed up" the mechanical fan by increasing rpms.... at least not that I know but glad your problem is solved.