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very high idle

Mudskipper

NAXJA Forum User
Location
Fitchburg , MA
I have an 87 XJ and was degreasing the engine bay. I then pressure washed the grime off and now it is idling very high. Are there any parts that are notorious for dying if they get wet? I removed the intake tube from the throttle body and put my finger over the square hole next to the butterfly and the idle came down. What's up with this?
 
You may have gotten the TPS(throttle position sensor) wet. It's mounted on the throttle body.

Also on the TB is the idle control motor. The little square opening is the air passage for idle control. Blocking the passage drops the idle?
 
The TPS is the most common culprit. Very few people ever get it to work correctly again after getting it wet.
 
It's the throttle position sensor, you can just about take it to the bank. I think just about everybody kills their TPS the first time they wash the engine. It is easy to change, two little torx screws hold it on, but if you ask ten people how to adjust it you'll get ten different answers. Maybe could get lucky like I did - I grabbed a used TPS at a wrecking yard for five bucks, then just set it up at the center of it's adjustment range, worked fine.
 
I have an 87 and it was stalling at stoplights adn if you tried to gun it from a stop. Says the tps is preset voltage from the factory. I just lined it up in the position the old one was in the best i could. you could see the screwhead marks, and it has been fine since. THat thing is expensive no matter where ya go, think it was $90 if i remember right. I also put in a new idle air controller at the same time, have to clean the tb out good first. Mine wasnt too bad since the motor only had 7k miles on it. Went cheap on the rebuild cause the two parts tested good, worked for about 7k miles before they wore out or i ruined the tps powerwashing the engine........who knows. I have washed the engine several times after the rebuild, so i dont know.
Cory
 
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