I noteced I had loads of oil in the throttle body and intake manifold a few months back. I fixed the backpressure issue I had and get no more blow back into the airintake. Today I removed the throttle body and sprayed it down with TB cleaner. I removed both of the sensors on the side and cleaned the one that gets pushed into the TB. I sprayed a bunch of TB cleaner down in the manifold where I could see and put it all back together. Now everytime I start the xj it idles at about 1600-1800rpm in park and nuetral and about 1100rpm in drive at a stop. Is there something I did wrong orshould look at? Btw its a 1990 4.0 renix engine.

 

Did you put a new gasket under the TB? Highly likely you have a vacuum leak, spray some TB cleaner around the TB, if your idle changes you found your leak. Search for renix IAC Test, or better yet PM cruiser54 for details on testing. You didnt turn the plunger on the IAC did you, as this can strip the threads and it will not function properly.

 

Mine did the same every time i do something to that area start it let it idle down then every time from now on it stops or at least thats how it worked for me

 

I did clean and scrub the idle speed stepper motor which is the round sensor closer to the fuel rail. It still does it from time to time I was told to try and replace that sensor and it will help it but its $54 non refundable part and I'd like to better diagnose it if possible.

 

If you applied any type of pressure to the pintle it's trash, replace it & move on.

 

Update: I replaced the air idle control motor yesterday then reset the computer by touching the negative to the positive for 30 seconds. Still have the issue. I know it it not a vacuum leak cus I have searched with spray to find one, IV set the tps to factory specs fallowing a few write ups IV found and I replaced the a.I.c. its got to be something I am missing. It never did this before I took the TB off the intake mani. I'm thinking tps next. Those were the only 2 things I touched.

 

TPSs are sensitive and have 2 sides to them. Sounds like yours is history.

BTW, Renix computers do not reset FWIW.