Hello, I have a 1990 Jeep Cherokee XJ RENIX. I have recently been having a very low idle after the engine warms up and its to the point where it will stall at lights and so fourth, At a cold start up it is not as bad around 500-600 RPM in Park/Neutral. Once warm though it begins the low idle issue. So far I have Replace
IAC
TPS- Which I set at the .8 volt as specified by jeep dealer
Tested MAP Sensor with meter it is working in correct way
Tested MAT Sensor/CTS Sensor it is working correctly
Replaced all Spark Plugs/ Wires
Replaced Vacuum Hoses/ Sprayed Throttle Body Cleaner to check for leaks found none
Also have cleaned the throttle body and I have a fresh oil change in her too.
Replaced O2 Sensor
Also Fairly New K&N Air Filter
Ran Sea foam through Vacuum lines to clean injectors.
04/22/10- Checked ECU it is not the problem I am starting to think fuel pump or fuel filter or pressure regulator...



ANY IDEAS???? PLEASE HELP!!!

 

Sounds like maybe your engine isnt getting enough air and or fuel. Air filter would be the first place to look. Also check your throtle body an make sure its not all gunked up. Check all the injectors as well.

 

I have a fairly new K&N Air Filter and I ran Seafoam through the vacuum line to get the injectors clean I will check them thoght just to be sure. Also I have tried 2 throttle bodys one original on the car and other used from another cherokee both very clean though.

 

I know the renix models have a throtle position sensor that you can adjust, but Im not familiar with them being that I have a 91. Try searching for "throtle position sensor" or "tps" and theres alot of threads that have info on adjusting them.

 

Ya I got a new TPS and set it to the dealer recommended volt setting of .8

 

I know this is an old thread but figured I would offer advice anyway.
There is a screw that is inside the block that the throttle lever on the throttle body sits against when at idle. I can't tell if it is a Phillips or torx head screw and there might even be a cap over it from the factory. But, if you screw it in a bit until you get the desired idle speed that should fix it. Sometimes the idle can go down because the throttle body is dirty and the gunk builds up around the blade and essentially chokes out the little gap that the factory set for mechanical idle set.

 

take some brake cleaner or like throttle body cleaner and spray over your vacum lines , intectors, and the intake manifold gasket, see if your getting air in there

 

That is a good method for vacuum leaks, but vacuum leaks make your engine idle high not low.

 

well ya it true depends were you spray too . i found out my intake manifold gasket was bad so im on my way to fix that soon

 

check exhaust manifold leak.... enough said

 

im with you on this one, but unscrew it for a higher idle

 

The screw head is on the back side of the block on the Renix so you would screw it in to make it go out farther on the other side to push the throttle lever out. But yes most throttle bodies are the opposite.

 

Get the Felpro gasket, they are the best. They probably make the factory one. It's cheaper and is as good or better than the original from the dealership.

 

ya i went to oreilys down the street and that the one they got its only 20 bucks