I have read almost every single other idle thread out there and found a few similar issues, but the solutions did not seem to work for me. So when I come to a stop, my 99 XJ's idle will not settle. The tach needle bounces up and down (not by much, but its constantly bouncing). It seems like it does it worse when it's cold, but it does it when warm as well. When I come to a stop at a light, sometimes I can feel the entire Jeep shake. It runs good for a few seconds, then shakes for a few seconds, then runs good, and so on. So far, I have cleaned the entire throttle body, cleaned and replaced the IAC and TPS, ran seafoam directly through the throttle body, ran Lucas injector cleaner through the tank, replaced the spark plugs, wires, cap and rotor, and replaced the ignition coil, all to no avail. I tired disconnecting the upstream o2 sensor and running it, but that didn't seem to do much either. I'm thinking it is either an o2 sensor or a bad cat. When I'm driving down the road at any speed above 25 mph, letting my foot off the gas and just coasting results in the idle bouncing around (it comes down, jumps back up, comes down, etc.). Any input would be greatly appreciated. Thank you.

 

Get yourself a $25 Vacuum tester Kit & go to the link below & pay attention to the various scenarios listed......

http://www.secondchancegarage.com/public/186.cfm

 

Fill out your profile or post your Jeep info in the thread. There is more than one fuel injection system used on these Jeeps and the methods used to diagnose them differ.

 

A couple of things to check are fuel pressure and vacuum leaks.

 

How come you took the grammar lesson out of your sig?

Hukt on fonix werkt 4 me.

 

I sawry, croozer!

 

Based on the simple prime test, my fuel pressure seems fine. It never gives me any problems starting. I have been researching vac testers, so that may be a next step. I'm also considering purchasing a set of Bosch 4 pin injectors. I will update.

 

Programbo here on CF has injectors for you. Contact him.