I've read a few posts here about idle problems after TPS replacement. This one has a twist I've never read about here, but it is something to check out if you are having idle problems after a TPS unit replacement.

I replaced the TPS as a matter of routine maintenance; our 2001 XJ has 151,000 miles on it and though it runs like new, it stays that way because I stay ahead of the maintenance curve, replacing worn parts before they become a problem.

I installed a "Made in the USA" Mopar 4874371AC TPS unit, which was identical to the OEM installed at the factory. It dropped right in with no problems. I buttoned everything up and started the engine. It idled WAY too high at about 1300 rpm. When the throttle was kicked, it would sometimes settle down to 1000, sometimes 1500 rpm, but nothing near 675 where it belonged.

A close examination revealed the problem: a sticky throttle plate that would not close properly. When I removed the new TPS for further study, the throttle plate moved freely again. BINGO.

Diagnosis: throttle plate shaft and/or TPS fitting slightly out of spec preventing throttle plate shaft from properly returning to idle position.

Solution: break out the Dremel and remove 2-3 mm of material off the end of the throttle plate shaft, so that it does not bottom out and bind up TPS rotation.

Add this to your list of "things to check" if you encounter idle problems after TPS replacement. Make sure the throttle plate shaft has the same amount of lateral play after TPS installation, as it did with the TPS unit removed, otherwise idle problems and/or premature TPS failure will result.

 

Top tip. Thanks for sharing...