On my 96 xj ive had a misfire that i could not get to go away. Today i did a compression test and cylinder one only had 50 psi. The jeep misfires terrible on that one cylinder, knocks, pops, and stumbles. Hovever if i loosen the exhaust rocker up about three turns it doesn't sound or skip as bad. What is my problem?

Thanks

 

did u determine why there's low compression? Did u perform a cylinder leak down test yet?

 

Yes i did, its leaking out the exhaust valve. When i loosen the rocker it doesn't leak as bad.

 

Is it possible the timing jumped? Either on the dizzy or cam?

 

if that did, then all the cylinders would be misfiring

 

Thats what i figured.

 

stuck valve?

 

excessive carbon build up on the valve causing it to not seat. I would see if you could do a steam clean on it an try to break it off that way. there is write up on it right here, https://www.cherokeeforum.com/f30/st...-4-0-a-226299/.

 

Cleaned the valves, no difference.

 

Looks like you'll be pulling the head off then.

 

Whats odd though is that yesterday i put about 3 tablespoons of oil in the bad cylinder and it ran fine for a three hour drive, after that it started running like junk again. Also what should timing advance be at idle?

 

that sound like your piston rings are worn out. Time to replace them

 

The jeep doesnt burn any oil at all.

 

I have exact same thing happening on my jeep. The oil ring is intact but the compression rings are worn out

 

I should also note that the jeep has perfect compression on the 5 other cylinders.