1988 Xj Aw4 4.0 "Bucking"
 

Ok I'd like to start off by saying today I replaced the A/C system on my xj. Before I did this I never had a similar issue than what is happening.

I was driving down the freeway doing 55, and out of nowhere the jeep bucked. Almost like it misifired or popped out of gear or something. It was a split second and didn't do anything but jerk the jeep. I continued driving and it happened 3 more times in that 10 mile ride.

I checked the trans fluid and found it was low. So I drained 1.75 QTS out of the trans pan from the drain plug and re added 3 QTS after I was finished. My trans fluid was dark and had a brownish tint to it. I test drove it after letting it warm up and fill up and in a 4 mile ride it bucked once.

I did pull the ignition coil plug to the dizzy when doing the a/c work to get it out of the way when dealing with rusty a/c fittings but other than that I did not touch anything special or do anything that would be concerning.

I replaced my fuel sending unit 2 years ago with a aitex full unit not just the pump and a few weeks back the pump was moaning and groaning pretty bad. I had no issues or bucks when it was moaning but I was still concerned I needed a new pump.

I have not done basic tune up on it since I've owned it, I will be doing some of that tomorrow but does anyone know or have had similar issue and had a remedy?

This issue is not on acceleration or breaking it has only happened while cruising at a steady speed between 30-55.

I had a similar issue on my wife's 88 usually after fueling it up. Turned out the ground wire for the pump inside the tank had a poor connection on one end and had begun to melt.

But, you coulda disturbed that old coil wire in the process of the AC repair, so eliminate that stuff first.

I'm goin going to take the coil to Autozone and have it tested, plus get some stuff for a tune up. Its just weird that it started after the AC repair.

At first I assumed it was the trans but I don't think its that anymore. Also if it was fuel related wouldn't it buck or jerk for more than a split second? Because every time it does it its just a really quick jerk 1 time then normal.

Get new wires, cap, rotor and NGK plugs into it gapped at .035.

If I damaged the ignition wire going to the dizzy cap would it cause an intermintent bucks like that? I'll get some parts tonight. Damn I gotta get this fixed. I thought all my major problems were done with this jeep.

Yep.

Alright I've got cap rotor wires and plugs waiting to get put it. Hopefully I get a chance after work tonight.

Basics, my friend. Basics.

Cap rotor wires and plugs are in and it hasn't done it since. I'll continue driving it and see if that feeling is gone.

No kidding? You mean normal maintenance can avert potential issues?

I'll be dipped in ****!!!!!

Good job BTW.

Haha well when I removed the cap I noticed one "prong?" Under the cap Was melted and chared with white stuff on it. The plug gaps ranged from .035 to .055 also.

Not one bit surprised. Did the cap have silver/aluminum contacts?

Good job of sticking with it as usual.

Same issue without a distributor, and mine is insane car struggles to run.

Can anyone help me with a possible solution?
Not tps
175k Im thinking it could be the upstream O2

I posted a thread but nobody ever replied

Post a link to the original thread. Did you also not include vehicle specs in that thread also? If so, that can account for poor response rate.

Well cruiser I hate to say it but the XJ bucked again today. It drove about 30-40miles after the tune up and did it again.