Calgary Jeep Association

4x4 Related Groups => Tech Talk => Topic started by: fug on February 25, 2009, 09:46:16 PM

Title: 95 XJ bucking while driving
Post by: fug on February 25, 2009, 09:46:16 PM: My daily driver (95 XJ, 4.0, AW4, 242 T-case) started bucking while I was driving in to work today. It appears to happen randomly but frequently... and is a pretty prounced hesitation/buck. It almost feels like a tranny shifting hard (it isn't the tranny tho). It's as if the engine stops for a split second and then restarts. I am pretty sure its not a misfire as it feels more pronounced than that. It seems to happen at any speed while moving but the Jeep seems to idle fine. The Check Engine light hasn't come on either.

I've looked around on a couple other forums and some threads I've read seem to say CPS or TPS. Anyone have those go bad on them? Do the sympoms I've described seem to fit with a bad TPS or CPS?

Thanks
Title: Re: 95 XJ bucking while driving
Post by: barmanjay on February 26, 2009, 12:31:55 AM: I would lean more towards the CPS

if it was the TPS,.. you would notice it with throttle movement

mind you I did have a similar problem and it was the TPS, however that threw the Check light on and the code came up as the TPS.

I don't think you'll get a code if it was your CPS

I could be wrong tho
Title: Re: 95 XJ bucking while driving
Post by: BlackYJ on February 26, 2009, 07:13:22 AM: How old is the O2 sensor? My gf's subaru would buck, idle rough and just run like poop and it turned out to be the upstream O2 sensor
Title: Re: 95 XJ bucking while driving
Post by: S-FLY on February 26, 2009, 10:22:49 AM: When is the last time the plugs/wires/rotor cap/button were changed?
Title: Re: 95 XJ bucking while driving
Post by: fug on February 26, 2009, 10:26:25 AM: I would say within the last 15 months. I bought this off another member a few months ago and I know that a bunch of club members went through it pretty thoroughly when his daughter was born a year or so ago.
Title: Re: 95 XJ bucking while driving
Post by: JENSSEN on February 26, 2009, 10:49:15 AM: For fun, disconnect the EGR valve ,... wiggle your CPS sensor and lastly check your dizzy rotor,.. cheap rotors allow the spring pin to break off and/or the contact tip twists. Last but not least bypass your ballast resistor on your DS front fender, just use a jumper wire :)
Title: Re: 95 XJ bucking while driving
Post by: Bnine on February 26, 2009, 02:03:28 PM: I'd be more inclined to check the colum that has had a bad ground and cause stalling issues since before you got the jeep. ;)

The EGR is all new from the dealer, you can try that but its doubtfull.

Ignition failures should throw a code, but again, you can check.

More then likely the colum is just about toast, and that connection is getting worse and worse.
Title: Re: 95 XJ bucking while driving
Post by: fug on February 26, 2009, 02:13:48 PM: I was thinking column when it first started too... but usually when the switch acts up it cuts power to the radio/fan etc... everything thats routed through the ignition switch. It just kills it all. This latest thing has a different feeling... the radio/fan don't miss a beat at all... the Jeep just bucks like you went over a big bump or the tranny shifted hard. Watching the guages nothing even flickers as its bucking.

I am definitely going to try replacing the column/switch this weekend. I just have a feeling its not going to help with this new issue.
Title: Re: 95 XJ bucking while driving
Post by: cLAY on February 26, 2009, 04:55:18 PM: I'll second the CPS. When I bought my '89 it would occasionally do this. Turned out that whoever had the tranny out last pinched the wiring between the block and tranny housing when they mated them back together.
Title: Re: 95 XJ bucking while driving
Post by: Waytec on February 26, 2009, 07:56:00 PM: I am going to go with karma because you made fun of the XJs.
(http://smilies.vidahost.com/contrib/ed/laugh.gif)
Title: Re: 95 XJ bucking while driving
Post by: XJHERO on February 26, 2009, 10:22:26 PM: Quote from: Waytec on February 26, 2009, 07:56:00 PM
I am going to go with karma because you made fun of the XJs.
(http://smilies.vidahost.com/contrib/ed/laugh.gif)
ha ha yup
Title: Re: 95 XJ bucking while driving
Post by: fug on February 26, 2009, 10:30:30 PM: Hey I never said there was anything wrong with station wagons... Great for getting me to work and bringing beer home ;D ;) ;D
Title: Re: 95 XJ bucking while driving
Post by: Bnine on February 27, 2009, 08:07:28 AM: Yeah if it isnt cutting out you are probably right. That does sounds like sensor related.

Did you say it was stalling on its own once in a while?
Title: Re: 95 XJ bucking while driving
Post by: fug on February 27, 2009, 08:20:45 AM: Most of the time when it stalls it only seems to be related to the ignition switch. The engine/radio/fan will die... then if I wiggle the switch everything comes back and I can restart. Pretty sure thats all related to the switch

I have had a few no start type issues occasionally where the fan/radio is working.. and the engine starts but immediately dies. That combined with the bucking is why I'm leaning towards the CPS cause from what I've read the symptoms would fit.
Title: Re: 95 XJ bucking while driving
Post by: Bnine on February 27, 2009, 09:56:16 AM: Sounds right.

You have enough 95's around there, start swapping a few sensors :)
Title: Re: 95 XJ bucking while driving
Post by: fug on February 27, 2009, 10:30:34 AM: Yeah I may be stealing parts off my other XJ... Normally with a sensor I'd grab a new one but I just phoned napa and they want $155 for one!

Anyone know anywhere cheaper?
Title: Re: 95 XJ bucking while driving
Post by: fug on February 27, 2009, 10:44:25 AM: Just in case anyone else goes looking for one.. found one at Parts source for $103.99
Title: Re: 95 XJ bucking while driving
Post by: Immortal on February 27, 2009, 02:31:59 PM: Did you try Chrysler?
Title: Re: 95 XJ bucking while driving
Post by: fug on March 01, 2009, 09:06:24 PM: Replaced the CPS and so far so good... no bucking and it starts up really nice. The true test will be driving back and forth to work over the next week.

I think I even managed to locate the one wire in my steering column/ignition switch that causes the Jeep to randomly die. Now I just have to redo the connector and I'll no longer have to be ready to throw it in neutral and restart at any point ;)