So the XJ isn't mine anymore I sold it to my brother and long story short, out of no where the idle will climb....at first it would only go up to about 2K but even that made it hard to stop. Yesterday it went all the way up to 4K and while standing on the brake jeep wouldn't slow down. he had to shut it off and e-brake to a stop.

he tried taking apart throttle body and cleaning thinking it might be getting hung up, no dice...have not found the throttle cable getting stuck, pinched or anything...

Has anyone seen this before? Any suggestions?

 

Sounds like a fuel delivery problem. I dont know of any other reason that the rpm would shoot up that high except that too much fuel is being delivered when it doesnt need to be.

 

Sometimes cleaning the TB isnt enough. It could be a bad IAC. Change that and see if it fixes the problem.

 

i had a similar problem. it turned out to be the spring that pulls the throttle back to the idle postion was loose/worn out. we grabbed the ends with pliers pulled them out and then wrapped it back around and clamped them back then all was good. Hope this is helps you.

 

I had that same problem on my 88 xj. With no foot on the gas, it would idle at 4k and was like having cruise control when my jeep didn't come with it.... It was scary. I would shift to neutral and it would then climb to about 5k rpm. As a short term fix, I would unplug the idle air control valve and plug it back in and that would "reset" it for a trip or two and then I would start it up later and it would do the same thing. I replaced the IAC valve and it took care of the issue.

 

my throttle gets stuck open full and its not the spring what else couls it be?? i can see some sort of linkage setup for the throttle cable can that be a possablity???

 

throttle cable mine did this going 70 and away we went replace it

 

I outline how to clean the idle air control in this thread. Worth a try...

https://www.cherokeeforum.com/f2/hel...ng-idle-67964/