Hey hows it going everyone. New to the site and figured I'd give it a try. The old lady's '92 stock XJ is jerking at low rpms in 3rd, 4th and 5th gear. Its a 4.0 4x4 manual. I just replaced the TPS and it wasn't that. Next on my list is to unplug the O2 sensor and see if that helps. It hasnt thrown a code or anything yet. Any ideas?

 

Not the O2 sensor, just tried it. Any other Ideas?

 

Hey, welcome to the forum! Especially welcome to more stick-shifters!

Can you be a little more specific with the jerking? Is it anything like a bucking? I've got something happening in any lower RPMs, though if I pop my foot off the throttle really fast it usually gives a good heave or two. If I let it idle along in 1st or 2nd then it tends to buck. For example, if I'm rolling through a parking lot at maybe 1500 RPM and just let my foot off the gas suddenly, I can guarantee you it will start bucking... sometimes amplified if the backlash is strong enough to make my foot hit the pedal again I think its a combination of whatever is causing my poor idle and dead suspension, I don't know enough to suspect engine/transmission mounts or not.

With that said, how's it run? Anything like what I mentioned sound familiar?

 

Ya pretty much, I replaced the tps, then iac. After the iac replacement, my idle is going crazy up rpm, down rpm and sometimes stalling. I
Anyone have ideas on what the heck is going on?

 

Let's get back to basics. Plugs, wires, cap and rotor? When were they last replaced?

 

About a month and a half ago, and ran fine after

 

Everything?

 

I replaced plugs, wires, cap and rotor

 

R u sure your cat isn't clogged? Happened with a car I had, but it was an automatic, eventually I had a loss of power then discovered the Cat was clogged.

 

I had that replaced around the same time as the other stuff for smog reasons ( gotta love California)

 

is it like a clunk right when you hit the gas? if so possibly driveshaft u joints, engine mounts... or is it partway through giving it gas?

 

Part way through hitting gas, when I let go of the gas, when hitting the gas etc

 

And not so much a clunk but a jerking and pulling , like towing a loose trailer

 

zwhiz may be on to something. Take his advice and check the u-joints and mounts.

 

Changed out the crankshaft position sensor yesterday, and now she runs pretty well. No more jerking or anything of that sorts, but the idle is lower now and she needs a little help getting started from cold.