1995 XJ 4.0 AX15 195k, ever since my last flop in wich I hydrolocked the #6 cyl with oil it's had a random misfire. Swapped out the #6 sparkplug misfire went away. Did some rips in a field still ran good. Let it sit for a bit then the misfire came back. It seems to go away when warmed up and always goes away above 2500rpm. Any thought? Could the O2 got messed up from burning all the excess oil? motor has been smoking randomly at high rpms/revlimiter for the past 2 wheelin seasons but still has plenty of power to rip donuts with the 42's. gonna do a compression test later in the week
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Misfire after Flop
- Thread starter ROBZ95Xj
- Start date
Ou2mame
NAXJA Forum User
- Location
- Long island, ny
It could be a messed up valve
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Sent from my HTC M9 using Tapatalk
- Location
- Southern Maryland
check fuel pressure
- Location
- Southern Maryland
if its bogging at high RPMs *until it warms up* it could be
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
Rather than throwing a bunch of expensive parts at it, do a wet/dry compression test on all cylinders. You may have broken a ring or bent a valve, etc.
Reread it, it clears up at high rpm. Exact opposite of fuel issue. Delt with fuel issues a couple years ago at NAC fest
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
Results on compression test?
- Location
- Murrieta
Your symptoms are similar to mine except the spark plug. I flopped my jeep, bumped the motor over a couple times to make sure it was clear, thought it was, fired it up and hydrolocked #6 with oil. Had a miss at idle but would clear up at higher rpms. Checked compression and found i bent a rod. Hope it's not the same for you, but x2 on checking compression.
hoping someone shows up with the tool this weekend
it wouldn't surprise me, hydro locked the #6 cyl 3 years ago after a roll, ironicly same obstacle. gonna try to do a test this weekend
Jesse_Hallum
NAXJA Forum User
- Location
- Here
You "rip doughnuts with the 42's at high rpms/revlimiter for the past 2 wheelin seasons," and a random misfire is your chief complaint?
If it blew up in a massive fireball, amputating both legs and your genitals, killed all passengers, igniting a 30,000 acre forest fire, AND you got caught doing it, THAT might qualify as a complaint. Random misfire? Give me a break.
Why do people treat their Jeep like crap and complain when it barfs?
If it blew up in a massive fireball, amputating both legs and your genitals, killed all passengers, igniting a 30,000 acre forest fire, AND you got caught doing it, THAT might qualify as a complaint. Random misfire? Give me a break.
Why do people treat their Jeep like crap and complain when it barfs?
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Jesse_Hallum
NAXJA Forum User
- Location
- Here
You did ask for "any thought", right? :wierd:
Got through a whole weekend of wheelin, still has the miss under 1500 rpms, above that it clears right up. There was one instance today where it wouldn't idle on its own unless you gave it some gas.
It doesn't like to crawl much and sometimes when it stalls under load I'll get a little poof back through the intake. Really lost on this one.
It doesn't like to crawl much and sometimes when it stalls under load I'll get a little poof back through the intake. Really lost on this one.
- Location
- NJ, U.S.A.
Random thought - when was the last time you cleaned the throttle body or ran a bottle of injector cleaner through the tank?
Maybe the #6 injector is a little gummed up from the hydrolock?
Maybe the #6 injector is a little gummed up from the hydrolock?
- Location
- Southern Maryland
you can also pull the rail and lay the injectors on cardboard, and watch the spray pattern that way
Never thought of that, thanks
- Location
- Rainy side of Washington
Nominated
Rob, did you do a leakdown test as well as a compression test? It may be that the engine is building enough compression when spinning fast (a compression test with all the plugs out but the one under test usually cranks pretty fast, too) but when it's running slow, it's got enough blowby or something to not get a good pop out of that cylinder. Maybe a cracked ring or damaged piston from the hydrolock is the cause? My 98 ran great above 3k rpm or so even with a 1/2" hole burned through the HG between cyl 3 and 4 because it was compressing the air/fuel mix faster than it could leak out. Anywhere below 2800 it ran on 4 cylinders, 2800-3k it ran even worse.
I answered you on FB but hadn't realized you already knew which cylinder was at fault.
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