I have a 91 xj that out out no where is running ruff as hell.

What i have tried:
Cap n rotor
Plugs
Fuel pump
Tested vaccum fuel regulator
Tested pressure at fuel rail (36 psi with old pump and new pump)
Tested for vacuum leaks
Fuel filter


Im at a loss. I did just pull the dist cap and there is quite a bit of free play it the dist shaft. Dont know if that could be the cause.

 

Coolant temp sensor? TPS? IAC? Cam sensor? Crank sensor (not likely)?

When is it running rough? Just at idle? While under load?

Any better info?

 

It runs rough all the time. At idle under load and just reving it up. When it gets to temp itwill kinda clear up but when you rev it up it takes a while to clear back up at an idle.

Ive also cleaned the throttle body

 

have you pulled the plugs out since you installed them to take a look at the condition? plugs can tell ya alot about a motor.

 

Yeah they look fine a little lean if any thing. Thought it was a fuel issue but nothing is wrong on that end. Now i feel its timing. Does anyone know how much lash you should have in the dist drive?

 

I would check for spark at each plug. Pull the plug wires out one at a time when idling and see if it runs rougher when you pull a plug wire off. If it runs the same when you pull a plug wire off, that's the cylinder where the problem is. I had this problem and when I pulled the number 1 plug wire-no difference. Turned out to be a valve problem. Your's could be spark related. Make sure you have good spark. Borrow a compression tester to test each cylinder as well.

 

i would check the injectors.
mine was missing and running like crap, changed everything spark related and it still ran like crap, just better.

so i started twisting my injectors while it was running, and wouldn't you know it, i had a leaky 3rd injector.

swapped em all out with some 703's and now she runs smooth as new.

the very odd time tho, it will idle and rev rough when i start it up. i know it's still injector related, cause i can make it worse when i play with my injectors/harnesses.

but if i shut it off and restart it, after a few tries, it runs fine again. this doesn't happen very often tho, like maybe once every couple of months.

 

I was thinkin injectors till i called the auto parts store and at. $56 a piece, i didnt want to go down that road

 

you could grab a whole set of six upgraded 703's for a member here,programbo, thats where i got mine, all six shipped were around 90 bucks i think.

but common sense would be to troubleshoot the problem..before throwing parts at it. But if it does turn out to be injector related, now would be a good time to upgrade.

IMHO, go back and check the basics, look at wiring for damage, check compression, spark output, vacuum leaks ect.

 

Its a gear to gear fit..so not much, maybe 2 degrees of deflection, if you have more than that, and at the same time the shaft is"lifting" as it rotates, take a look at the dizzy shaft bushings, i fit move more than that without lifting much; check weather the roll pin that holds the gear to the shaft has broken.

 

check for codes !

 

No CEL

 

So? Did you check for codes?

What kind of spark plugs are you running?

Also +1 pulling spark plug wires (or injector wires, it's a little safer...) while the Jeep is running to see if the problem is a single cylinder.

 

What about your ignition coil..