-   ZJ Grand Cherokee Forum (
-   -   Weird engine problem... (

Tigersan 11-22-2012 01:24 PM

Weird engine problem... ZJ 5.9
Hello, i have bought 98 ZJ 5.9 few months ago. Was running great
for a while. Some time ago i got pissed at this guy driving infront
of me so slow so i just pushed pedal all the way down and passed
him rpms went high but not in the red field or anything. Check engine
light started flashing then it stopped, engine was working fine no
problems. I got back home, and next day when i was stopped at
the light signals, while idling it started misfiring almost died, but i
quickly shifted to N and gave it a little gas, and it went away...
"WTF" i thought. After a while it did the same while driving, went
away, after quarter mile or so... check engine went on solid. Got
home checked the code it was P0302 - misfire. I didnt do anything
yet, i was waiting for my friend to call me back on it, hes a mechanic.
Drove to get some food and the engine died on me while i was
taking a turn, almost hit the light post because of power steering
and brakes barely working. I Stopped, turned the key it started no
problem, but something was wrong, the exhaust didn't sound right,
also sounded like one or more valves started making noise, not loud
but "ticking" noise that got louder the higher i revved the engine,
and it was misfiring on one cylinder constantly now. Went home,
checked the code again and this time it was P0302 and P0307.
Went to auto zone bought spark plugs and wires and replaced them,
distributor cap looked new so i didnt touch it. Cyl7 sparkplug was
bent in, so the space between electrode was barely a milimeter. Weird,
how did it get bent? After replacing all plugs and wires, check engine
doesnt light up - no codes. And engine doesnt work right. There's
no misfire, unplugged every injector separately and when i did,
engine starts jumping everytime i unplug the injector on each cyl.
- works on all cylinders. Sounds like valve/s on one cylinder
are loud (ticking sound), sounds like its cyl #7. It lost some power,
and exhaust sounds weird. Engine idles steady no jumping etc
except this vibration as if one cylinder didnt produce as much
oomf as it should but its regular...

My dad says that probably when i gave it some fire some carbon
buildup from the piston could tear off and get into valve/s and
thats why its loud and lost compression... I havent checked
compression yet. When i bought it, i changed the oil, it was black
as tar. I changed the oil again few days ago, after just 1000 miles to
see and it was dark too, not as dark as before but dark...
Guessing previous owner/s didnt change oil too often... I did upper
engine treatment with seafoam twice through vacuum line. And
poured "Restore" oil treatment to the oil few days ago after an oil
change... So far the valve seems quieter, it sometimes has more
power sometimes less. Hard to put a finger on it... weird...

Just wanted to hear what you guys think before i go
all out spending money to fix this thing

Thanks for any thoughts in advance.

ZeeJay1997 11-22-2012 04:39 PM

Clogged exhaust, probably cat.

jt_armstrong 11-22-2012 09:03 PM

Its worth doing a compression check to see full extent of problem. The plug with the small gap may have been there before you bought it rather than having been caused by something you did. The ticking could be anything including a broken piston ring or sticking valve so you just need to get back to basics starting with cylinder compression.

jnowak 11-22-2012 09:14 PM

The flashing light is saying the cat is getting to much o2 and results in the cat getting to hot. Could be a bad cat or misfire. Also one thing I was taught is cat don't die they are killed.

Tigersan 11-25-2012 11:43 AM

Thanks everyone for the replies... Looks like its getting back to normal.
Everyday i drive it the pinging/clicking is quieter and quieter, and it
regained the power... so its all good... ill just change oil more often for
few months, to flush it good...

I had a thought, i saw many youtube vids of people supercharging the 5.9.
Does that require any drivetrain modifications? Will the T-Case and tranny
be able to withstand power increase? Anyone heard or knows how far can
you charge the 5.9 without doing any serious mods to the drivetrain?


ZeeJay1997 11-25-2012 06:20 PM

I wish I had a Jeep that fixes itself. ;)

dusterdude 11-25-2012 06:25 PM

I think you floated a lifter,sounds like its pumping back up

Tigersan 11-25-2012 09:47 PM


Originally Posted by dusterdude (Post 14506326)
I think you floated a lifter,sounds like its pumping back up

Have no idea what that means hehe, but im hoping it will get it self settled
100%. Do you have any links how the lifters work?

JasonStebbins 11-25-2012 09:50 PM


Originally Posted by Tigersan (Post 14507558)
Have no idea what that means hehe, but im hoping it will get it self settled
100%. Do you have any links how the lifters work?

Not a 5.9L but this is how a lifter works.

Tigersan 11-27-2012 04:48 PM

Hey this sounds like mine but mine is alot quieter... i know the cover is off on this one but still its ALOT quieter.

Tigersan 08-20-2013 03:09 PM

Yeah I know its been a while. But finally last week i left my car in a shop to do the lifters.
Atleast I thought it was the reason for the pinging noise. But guess what they replaced
the lifters and injectors and it still ticks like crazy...

Any suggestions or ideas? You can hear the noise from the left bank by the driver. Sounds
like cylinder 5 or 7. Noise is quite hearable, and gets louder with the rpms. The mechanic
said they will keep looking for the probable cause. But its quite unnerving I have spent $800
for the work already and the problem is still there... Other than the noise the engine is
working smoothly and its fine its just that the noise is driving me crazy.

Would be grateful for any ideas? Thanks!

zj97ltd 08-20-2013 04:51 PM

Did they do a compression test? If so did they share the results with you?

HighLonesome 08-20-2013 05:18 PM

^Do a compression test to find the bad cylinder. Or...

Pull the drivers valve cover and start her up. Determine which cylinder is ticking by using a stethoscope. Or maybe you will spot some carnage like a bent pushrod or broken spring. Once you know what cylinder it is, remove the rocker and pushrod and inspect for damage. Make sure the springs are intact.

Tigersan 08-20-2013 06:33 PM

They didn't do compression tests. Ill ask them. According to what they
said, there was no visible damage to push rods, rocker arms, nothing.
And the engine is VERY clean inside... It's a little suspicious. All this
considering they are telling me the truth... That they even replaced
the lifters... :/

jt_armstrong 08-22-2013 11:29 PM

Might be a cracked exhaust manifold. I had one of those once which caused a metallic ticking noise. This would also give you an explanation for the check engine light having come on..

The time now is 02:09 AM.

Powered by vBulletin Version 3.8.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.