rattrapp

Well I'm hoping someone may be able to give me some other idea of what may be causing my 91xj to buck and hesitate while running at low rpm also if I've been driving and it has started to do this bucking and hestiating I can put the transmission in nuetral and it will contiue to run rough if I can hit the right low rpm (no tach). So far I have replaced plugs, wires, cap, rotor, distributer, fuel pump, fuel filter, fuel pressure regulator, o2 sensor, oil, oil fliter, air filter, I tried replacing the ignition coil but every one I got from the autoparts store the plug on my jeep was to loose so there was no good connection between any of the coils that I tried. I also did a factory reset of the ecm and it still does the same bucking and hesitating. I used a vacume test gauge and seems like the vacuum system is fine too. Pressure at fuel rail is 34 psi. Thanks for reading and any help or advice in advance.

rattrapp

BlueRidgeMark

Duplicate thread. Let's let this one die.

https://www.cherokeeforum.com/f2/sli...-91-xj-245190/

cruiser54

Done.

Has the throttle body ever been cleaned?

Check your intake manifold bolts to see if they're snug.

How's the vacuum line to your MAP sensor?

BlueRidgeMark

Thanks, cruiser.

Odd about the coil.

rattrap, what coil are you using now? The original one? Where exactly is it too loose?

If the coil or its connection is flaky, that engine is not going to run correctly. Help us understand this "too loose" business.

Of course, cleaning the throttle body & IAC is almost free and should be done anyway.

rattrapp

So I already cleaned the throttle body also, when i said to loose I was talking about the fit of my plug to the female plug on the coil. None of the coils that any store had were the right plug, my plug would fit but not tight so there was no good connection.

cruiser54

Plug wire connection or the small plug with a harness?

rattrapp

cruiser54

But which connection are you having issues with on replacement coils???

rattrapp

The small plug with the harness.

cruiser54

Check your intake manifold bolts to see if they're snug.

How's the vacuum line to your MAP sensor?

rattrapp

As far as I can tell the vacuum system is fine. I used a vacuum gauge and found no leak.

rattrapp

Ill check the bolts after work today.

PatHenry

I would start it up and then jiggle that connector that's loose and see if the engine reacts. I would use a pointy stick to do this for safety (maybe a marshmallow roasting stick) - the idea is just to see if that loose connection is causing the problem. If you jiggle it and the engine starts going wonky (or wonkier -- or even better for that matter), then you need to replace the harness, if the engine doesn't react after a few pokes and prods, then you know the problem lies elsewhere. Then, after that you can roast some marshmallows.

rattrapp

so I went out to my Jeep at break time started it up jiggled the wire connector the connector going into the coil was not loose but when I touched the two wires going into the wire harness near the ignition coil the Jeep shut off so I imagine I have a broken wire so thank you for the tips and advice when I get home from work today going to see if I can find the broken wire and fix it and see if that fixes my problem thanks again everyone.

PatHenry

Well, you've made progress. Hopefully just a wiring fix and you'll be back in business and ready for marshmallows and beers.