Another xj having problems..

So first of it is an 89xj limited 4.0. The problem i'm focusing on now is that it seams to idle fine, maybe high at times. has died once or twice since summer, but started back up and ran fine. So it idles pretty good, but when I get on the freeway, need power, or get on the gas it starts stuttering and spitting hardly increasing speed. The last time I went wheeling it started to do this. It seamed like it went away for a week but, came back and has not gone away. I plugged in the snap-on to test the basic sensors and everything turned out fine except the coolant temp. sensor so i replaced the and helped a little. It also has a new o2 sensor with a fairly new cattilac convertor.I did take the exhaust off for a day to see if anything changed but ofcourse nothing did. Also, the fuel injectors are two years old and has a good fuel filter. It is running almost like it did when the fuel injectors went out; I dont think its the problem, but how do i test/check them. I am in need of help now. I have not been driving it so much in the past month or two, but I do need to start driving in the next few weeks. All help is appreciated. Thank you.

unfortunatly my experience is with a 91 ho engine which is different. on mine it would idle fine but made no power above about 1200 rpm.and when i asked on the board here about it ,it turned out that ~1200 rpm was pretty indicative of a crank position sensor. and it was. that was the reason i joined naxja. i am not sure how the renix system cps is configured so this is probably of only limited use to you. but maybe this will get the ball rolling with some renix based answers.

Check your AIS or clean your throttle body, then check your EGR system for operation. Typically the diaphram fails and does not operate the EGR valve.

Thank you for your help. So how do I tell if the diaphram is failing. How do I check egr operation. I assume to check the ais I check the voltage. I heard recently that the fuel pump can be bad, but work at times. Today I drove the jeep around a little and payed more attention to it. It does run fine at times and at times it doesn't. It will be lacking power then it will just take off. Sometimes it will just keep spitting and stuttering. It usually has been happening around 2000RPM. I cleaned the throttle body maybe 6months ago, but i will take it apart and clean it again. It does seam like it is missing when it starts stuttering. Any ideas. Once again thanks for the help.

sjx40250 said:

Check your AIS or clean your throttle body, then check your EGR system for operation. Typically the diaphram fails and does not operate the EGR valve.

Click to expand...

What is an IAS? Do you mean the IAC? (IAC=Idle Air Controller or the ISSM= Idle Speed Stepper Motor or IACV = Idle Air Control Valve which of course are the same darn part). So far I have found 3 FSM names for this part!

Have you checked the basic stuff, like the Cap, rotor, spark plugs, HV wires, HV Coil, TPS, to name a few. If you search this forum (OEM) you will find additonal details on testing each one. This should get you started.

Also go to these sites for FSM mauals on the Renix Engine control system and diagnostics charts, and other how to's etc:

http://www.pirate4x4.com/tech/billavista/PDFs/Jeep_Renix_Fuel_Injection_manual.pdf


http://www.fordf150.net/howto/diagnoseengine.php

I had a similar problem with mine. I replaced the fuel pump and haven't had a problem since. It ran pretty good most of the time until you started working it. Mine is also an '89 if that helps.

Thanks for the great help. I was not able to work on it this past week or weekend. I will hopefully get to it very soon and will try everything reccomended and will let everyone know the outcome. Thanks