jeep1998cher

New guy here I'm hoping some one can help me out and that this is the right place Here is the issue

98 Cherokee 5.2L just under 200,000 miles has a high idle I have cleaned the t-body replaced the IAC and coolant temp sensor, thermostat and disconnected battery for about 30 mins no codes check engine light does work the way it should

Doesn't matter if engine is hot or cold.

Start engine idles just fine for about 20 seconds or so later the idle increases to aprox 1500 rpms

Give the gas peddle a quick stomp and the idle goes up and then back down to where it should be and 20 or so seconds later its back up to around 1500 rpms.

We just bought it paid 900 for it knew that it has some issues the first issue that it had is that it would not idle at all unless you reved the engine to about 1500 for a min or so then it would idle fast . Cleaning the T-body fixed that now I have high idle issue


Thanks guys/gals for any help

salad

Welcome to the forum! Assuming ZJs work the same way search for tjwalker's TPS test and give that a shot. It's possible you may also have a vaccuum leak, use short spurts of carb cleaner spray around the TB and other places on the intake manifold. If the engine sucks any up you'll hear the idle change. (do it while running)

By the way, the "GRAND" on your Jeep is not a trim level. Grand Cherokees are different vehicles from Cherokees, we actually have a specific forum sub-section for them. The drivetrains are different, the 5.2L and Chrysler 42RE (or whatever) never came in any Cherokee.

jeep1998cher

I did look for vacuum leaks none found could you post the link for the tps testing I searched but got nothing