High Idle on '88 Cherokee

Our Cherokee did exactly that 3 years ago. It was a dirty connection on the TPS or throttle position sensor. I unplugged it and cleaned the contacts with a spray cleaner, WD40 works and it was perfect for 2 years. I had to clean it again last summer.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"F. Robert Falbo" wrote:

There is no such animal on a 88 XJ.

Most likely a bad TPS or TPS connection.

Oops! It was the plug right next to the TPS. The Haynes manual didn't ID it, so I guessed it might be a coldstart function.

Thanks. I checked the connection, and it looked fine, but it still could have had something interferring, so if it does it again, I'll work a bit more on the female connector. If that doesn't work, I'll probably replace the TPS.

-bob-

Thanks Mike. I got the same answer from another guy, so I checked the connection. It looks fine but the springee function of the female side may be weak after 16 years, so if it continues to malfunction, I'll tighten the female side, and if that doesn't work, replace the TPS.

-bob-

Mine looked really clean too....

They are a low power computer connection, it takes very little to mess them up.

Mike

that would most likely be the IAC (idle air controller)- it's just another thing to clean ;) if you have a few minutes, you can pull the throttle body, remove and clean the sensors, then spray some carb cleaner (or TB cleaner) through the TB to remove deposits. Note that if you have an automatic, your TPS will have 2 connectors- one for the engine computer, and one for the transmission computer. the IAC will have its own connector.

Bill, thanks for updating my terminology- still used to my old Nissan, I guess ;)

I only mentioned cleaning the idle stepper due to the fact that there may be uneven buildup on the pintle seat, tricking the computer into thinking that it's closed all the way, when in fact there may be air getting past it, resulting in a high idle.

i've made cleaning the TB on my '87 XJ (and checking the related sensors) a normal maintenance item every 6 months or so.

Yeah, but the 88 came with the French Rennault/AMC MPI FSM which calls it the Idle Air Control .

When you clean that sucker, remove it and clean the shaft and p> Hi Chuck,

Will Honea did pass the time by typing:

Just don't remove the shaft from the motor or it's farked. (so sayeth the service book anyhoo)

I missed that the first time thru and turned the engine over with the IAC hanging loose - that damned pintle came out of there like a bullet! Fortunately, all the parts wound up in a towel laying under it but it took a fair amount of fiddling to get it back together - it CAN be done. I echo your comments - DON'T. The other thing that will get you totally screwed up is moving the idle stop screw that sets the minimum closure for the butterfly. I never did find a spec for the minimum throttle plate spacing - finally went out and measured one to get mine back to where it belonged.