I have an 1988 XJ 4.0. I have been fighting a high idle and rough idle. So i replaced the TPS and that cured the rough idle, i also thought that it cured the high idle but no it didn't. Then i replace the IAC thought that did it for the past couple of weeks and now it is back. It seems like a choke it stuck open. Any ideas?

thanks for the help

 

Pull the new IAC and make sure it is clean and that it actually moves when you start the Jeep. There may be a intermittent break in the harness leading to it.

 

idle adjustment screw... actually im not sure if the renix had one but id check... otherwise pull your throttle body off and clean it with some TB cleaner... scrub it down and the sensors down...

 

Replace the intake/exhaust gasket.

 

possible also... but try shooting starting fluid around the intake and head seal first... if it idles up more then you have a intake gasket leak...

 

I will check the TB and the intake gasket this week end and let you know

thanks