#2 misfire

fergmonster · May 12, 2005

ok, i got a new jeep last week. The second cylinder from the firewall,(i think its #2) is missing, not firing whatever you want to call it. i have swapped plug w/another cylinder, and changed the wire w/other jeep. I think my problem is internal. Perhaps a hole in piston.(it was running pretty lean from the looks of the plugs) The former owner showed me the plugs that were in this jeep before he sold it to me. they are disintegrated!! If i remove the dipstick, it has severe blowback coming out of it. I pulled the valve cover and the rockers seem to be operating correctly. (hopefully the valves are opening). What do you guys think it'll be? i'm gonna pull the head this weekend and find out. Should i do a rebuild on this motor? or should i replace this motor and build up a spare/stroker since i have two xj's now? would love to turn the 94 2dr into a "sleeper". thanks for all your replies!!

Matthew Currie · May 12, 2005

fergmonster said:
ok, i got a new jeep last week. The second cylinder from the firewall,(i think its #2) is missing, not firing whatever you want to call it. i have swapped plug w/another cylinder, and changed the wire w/other jeep. I think my problem is internal. Perhaps a hole in piston.(it was running pretty lean from the looks of the plugs) The former owner showed me the plugs that were in this jeep before he sold it to me. they are disintegrated!! If i remove the dipstick, it has severe blowback coming out of it. I pulled the valve cover and the rockers seem to be operating correctly. (hopefully the valves are opening). What do you guys think it'll be? i'm gonna pull the head this weekend and find out. Should i do a rebuild on this motor? or should i replace this motor and build up a spare/stroker since i have two xj's now? would love to turn the 94 2dr into a "sleeper". thanks for all your replies!!

It sounds as if there is something very wrong, and if it isn't a holed piston I'd guess either a burned valve or a broken ring. If I were in this position I think I'd still do a compression test, or at the very least a vacuum test, before taking off the head. It would be a real shame to yank the head and then find out that it's a bad injector harness or something! I think the question of rebuilding will probably depend on what kind of failure it is and what damage if any. If one piston was holed from overheating and lean running, you'll have to evaluate them all. If a ring broke it might have gouged up the cylinder wall. If the previous owner cooked the crap out of it, it could have worn cylinder bores, bad bearings, collapsed pistons, you name it. On the other hand, if it's a burned exhaust valve, you might have an easy fix.

Dirt · May 12, 2005

do a compression test on that cylinder and check it with at least 2 more they should be about the same. if it is the same check your injector pulse. if not the same (or close) put a squirt of oil down the sparkplug hole. if the compression comes up you need rings if not you need head work.

Dirt · May 12, 2005

that's the #5 cylinder btw. not that it matters.

comancheon33 · May 12, 2005

If the plug looks lean. I would be checking compression, vacuum, and would try an injector before I tore the head off. Swap the injector with a another cylinder and see what happens. Its fairly easy and free.

fergmonster · May 12, 2005

i will do a compression test, and swap an injector tonight. thanks guys!!

#2 misfire

fergmonster

NAXJA Forum User

Matthew Currie

NAXJA Member #760

Dirt

NAXJA Forum User

Dirt

NAXJA Forum User

comancheon33

NAXJA Forum User

fergmonster

NAXJA Forum User

Similar threads