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RandomHero89
05-01-2015, 09:16 PM
I have a 99 xj sport and when I drive it the rpms will jump up and down and it acts like it wants to die. But if I put it in 3rd gear it doesnt do it as bad but still will do it every now and then and also if I keep the rpm around 1900 2000 rpms it seems to have no problems.now for a list of things ive tryed to do to fix it.
.new distribtor
.new plugs &wires
.new coil pack
.cleaned idle control senser
Thanks to anyone willing to help me out here

OldFaurt
05-01-2015, 09:58 PM
I have a 99 xj sport and when I drive it the rpms will jump up and down and it acts like it wants to die. But if I put it in 3rd gear it doesnt do it as bad but still will do it every now and then and also if I keep the rpm around 1900 2000 rpms it seems to have no problems.now for a list of things ive tryed to do to fix it.
.new distribtor
.new plugs &wires
.new coil pack
.cleaned idle control senser
Thanks to anyone willing to help me out here

Here is something to try,
open hood
pull hose from Brake booster and plug the hose with something that won't fall in!
Start jeep and see how it idles!

Would not drive it this way as you would have crap for brakes!

If the Idle stabilizes, you might need a new brake booster!

Of course there is also that dang crank / Cam position sensor...

:watermelon:

4.3LXJ
05-01-2015, 10:11 PM
Welcome Dustin. I can tell this Jeep needs to feel loved. There is one thing no one ever changes on these things and that is the O2 sensors. Most neglected tune up part ever. They are hiding down by the catalytic converter. They give the exhaust gas mixtures info to the ECM. They wear out over time and give false information causing the ECM to make a fuel/air ratio that is not ideal. I would change these first and clean the idle air controller, which won't cost you more than a buck ninety-eight. That will probably take care of most of it

RandomHero89
05-01-2015, 11:40 PM
Thanks ill check the brake booster a try and then ill check out the o2 sensor

nickyg
05-02-2015, 01:23 AM
Have you checked the throttle position sensor? It's easy to do. here's a video on how it's done.

https://www.youtube.com/watch?v=URNYaGXM_uQ

RandomHero89
05-07-2015, 09:59 PM
Today I pulled my throttle body off my xj today and and took it apart and give everything a good cleaning and it seemed to help alot but it still has some hesitation and rpm still bounce and stutters around 1900 rpms. Also noticed if I put it in 3rd gear and not in drive it runs better