1991 XJ Stumbling, Bucking, Lacks Power Under Load/Acceleration

[Ecomike]

Disconnect the O2 sensor and see if the problem goes away! If it does the problem is with the O2 sensor or its wiring/connector

I had the same problem 3 months ago. Turned out I had the O2 sensor and the TPS sensors both attached to the wiring harness backwards (C connected to A instead of A connected to A). They were both fairly new parts too. But mine was behaving badly all the time and yours comes and go. If it comes and goes it is more likely electrical!!!!!!! and not a camshaft lobe problem.

If it still runs fine in reverse then forget the cam lobe problem the dealer suggested.

Could it be the transmission, TCU or a TCU wiring problem????

Have you pulled and cleaned all the ground wires yet?!!!!!!

Could be a loose, dirty ground wire for sure!!!! Jeeps are notorious for ground problems. Search here in this forum for gound problem stories, where the ground connections are and how to fix them.

Also check the serpentine belt, the tight turn voltage drop / head light dimming sounds like a loose or greasy belt.

 

[adamxsquared2000]

Sometimes eratic tachometer movement can indicate a faulty coil.

 

[SlipperySquid]

I removed and cleaned the transmission Neutral Safety Switch and still have the same problem. Something new I noticed.... when I hit a dip in the road or large bump such as a speed bump, the engine starts running fine. To me, this indicates an electrical problem, such as a wire shorting to ground.

All of the symptoms previously described seem to indicate a problem somewhere in the ignition circuit.

My plan is to visually inspect every wire or wire bundle. Next, I'll check the 60 inputs to the computer for a ground....

Any other ideas??????????????????????????????????????

Thanks for the feedback.

 

[skipc]

I agree with ignition... You said it 'cuts out' - that's defintiely not a sensor or exhaust problem. Even if a sensor, it would not cause a cut out, it would stall, or more likely, go into a limp mode where it might not be as peppy, but it would be consistently not-peppy.

A ground, or a plug wire... maybe the coil.

 

[Ecomike]

Something new I noticed.... when I hit a dip in the road or large bump such as a speed bump, the engine starts running fine.
Any other ideas??????????????????????????????????????

Thanks for the feedback.

Sounds like its definately a jeep, just drive it on bumpy roads with lots of pot holes and keep on rollin! :roflmao:

60 inputs! :scared:

 

[SlipperySquid]

Problem solved. A ground wire to the MAP sensor was broken inside the large wire loom attached to the firewall. The Engine is once again running strong. Thanks to everyone who helped.

 

[RaccoonJoe]

let me know if you have any relief. from what you explained mine sounds to be the exact same. i was told by a few mechanics the it might be the IAC but i dont want to go in and start replacing stuff like you did to have no avail. also i am experianceing high idle. once i start it and it gets warming up. it idles about 800 when i first start it. as it warms up the RPM's will climb while ildeing. once it reaches about 200 it idles about 3k. you have any idle symptoms?

just me, but isn't this every symptom of a bad TPS??

 

[snufalufagus]

yes mine started out with some of these but when it went south on my 93 XJ 4.0 it went into limp home mode. Plus this fit my Crank shaft possition censor problem as well. my .02 cents.