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SPOOKY high idle

710 views 4 replies 4 participants last post by  JEEPTECHNICIAN 
#1 · (Edited)
Mornin' folks!

This morning, as I was driving into work, my Jeep was idling way high. It's an '87 4.0, manual...I don't have a tach, so I can't say for sure, but I'd guess it was up to at least 3000 rpm. I didn't need to rev the engine when letting out the clutch...

I've noticed this before (but not as high rpm), particuliarly when it's wet out. It was raining this morning.

Any Guru's have an idea what could be the problem? Choke? Computer? Bad sensor?

Oh yeah, i should probably get a shop manual...wnyone know where I can get one?

Thanks,
Wes
 
#2 ·
Wes, it's Wes. I had a similar problem about a year ago. I found it was the throttle body linkage. A little wd40 at first, and then some grease, oil her up, and she was fine. I thought it was the throttle body return spring at first, but when I popped the linkage apart, and felt the play, there was no doubt that it was the linkage bar. I took a picture, but it came out horrible, should have used the flash, but you'll get the idea.

I have an auto, and it was sticking for a couple days, and on the last day before I had to pull over and really take a good look. The throttle was sticking so bad, I was standing on the brakes to try and stop her. I was in traffic, and I put it in neutral and the engine would rev to 2500rpm. I was getting some weird looks until I stopped at a garage and figured it out.

-Wes
 
#3 ·
Thanks, Wes. (Ok, that just feels wierd...)

I'll give it a shot right now...

W.
 
#4 ·
I had a similar problem on my dads' '87 XJ with the manual transmission. When I would start it, it would rev to about 3000 rpm and it would stick there for about a minute before dropping to normal idle.

What I did to fix it: Remove the intake tube from the throttle body, turn the Jeep on, and then cleaned out the TB with carb cleaner a little shot at a time. Turns out that one of the sensors was just clogged up with gunk buildup for years of driving. Since then I have not had a problem with it. I clean it out every two years, just to keep it clean in there.
 
#5 ·
CANT SAY IT ENOUGH, CARBON CLEAN, CARBON CLEAN,CARBON CLEAN. Go to a chrysler dealership and ask for combustion chamber cleaner. Get engine at operating temp, remover intake tube from throttle body and spray in throttle body until can is empty. spray in there all over and into the air by-pass passage real good. It is going to run like crap and smoke while you are doing this but keep spraying until can is empty. do not spray to where engine stalls just on the edge of stalling. When can is used up turn off immediatly and let set for 30 minutes. Then go make somebody mad when yoy severly smoke up the neigborhood.
 
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