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High Idle Problem

quadna71

NAXJA Forum User
Location
Delaware
We bought an '01 Sport last night so now the '87 Chief will be looking for a new home. I have an issue that needs to be fixed before I sell it and am hoping someone can point me in the right direction. I cleaned the throttle body out two months ago - it was caked so thick that I'm surprised the butterfly even seated shut! Well, an old toothbrush, can of throttle body spray cleaner, and 10 minutes later is it so clean you can eat off of it. It coughed once or twice when I started it back up but figure that was just the residual gunk and cleaner working it's way through. All is good in the world and it seems to be running even smoother than ever. Then about 5 minutes into my drive, just as the engine temp gets up to normal, I realize that the idle is much higher than normal. In neutral it'll hover between 1500-1600, but only after the engine has warmed up.

I remember seeing a many-paged thread about the idling issue but can't seem to find it no matter what I put into the search box. Can anyone clue me in to what I need to look for/adjust/replace in order to get the idle back to normal? I don't want to sell a Jeep unless it's running great!

1987 XJ, 225K miles, stock aside from a 2" spacer/shackle lift.
 
If this idle issue JUST happened after cleaning the throttle body and idle air control, the pintle on the iac is most likely not working properly.

Did you remove the IAC and clean it when you cleaned the throttle body? Usually best to combine cleaning of both of these.

And know that cleaning can, but does not always restore function. Sometimes replacement is necessary.
 
WAD357 - Nope, I didn't make any adjustments to the TPS. Just cleaning what I saw in front of me.

birchlakeXJ - Yes, it started immediately after cleaning the throttle body. I just finished removing and cleaning the IAC very well with a soft toothbrush and throttle body cleaner (sensor safe - same as I originally used). Still no change. Starts perfectly fine, idles perfect, and then starts creeping up as the motor warms up to peak out around 1500-1600.

I have plenty of tools - how do I adjust the TPS? I'm assuming I'll need my multimeter to check/adjust...but not sure how and what I adjust it too. I have a FSM for back then too but it isn't giving me much direction.

Thanks!
 
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