Cherokee not running on all cylinders
09-08-2011, 12:35 PM
#1
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Year: 1998
Model: Cherokee
Engine: I6
Cherokee not running on all cylinders
Ok I'm new here and i need HELP! I have a 98 cherokee and its missing on 3 and 4. I've done distributor, cap, wires, new injectors, front o2 sensor. new plugs. I seems that at about 3000 rpms you can feel them all kick in but when it shifts it goes back to just 1,2,5,6. I'm getting misfire codes po300 po303 and po304. I tryed erasing them but they just come back
. I've tryed seafoaming the intake and gas but no change even took intake off to clean no change. The injectors are all working and i have spark (checked). Any help would be great . Thanks
. I've tryed seafoaming the intake and gas but no change even took intake off to clean no change. The injectors are all working and i have spark (checked). Any help would be great . Thanks
09-09-2011, 11:24 AM
#3
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Year: 1998
Model: Cherokee
Engine: I6
K so i ran the test and came back with 155 on all cylinders but 50 on 3 and 4 so could it just be weak valve springs?
09-10-2011, 02:49 AM
#7
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Year: 1997
Model: Cherokee
Engine: 4.0 L
Ok,
Now you know that you are missing some. You need to find out if it leaks in the rings or the valves.
Maybee you can rent a tool to do a leaktest. Adding air into the cylinder can tell you, by listng to where it escapes, where the problem is. If it blows n the intake or exhast, you got a burned valve, if it blows in the valvecover you got bad rings or worn cylinder.
The teory of bad springs would result in problems in high rpm and not notiable in idle.
If it turns out to be a valve, you need to replace it.
Good luck and let us know
Now you know that you are missing some. You need to find out if it leaks in the rings or the valves.
Maybee you can rent a tool to do a leaktest. Adding air into the cylinder can tell you, by listng to where it escapes, where the problem is. If it blows n the intake or exhast, you got a burned valve, if it blows in the valvecover you got bad rings or worn cylinder.
The teory of bad springs would result in problems in high rpm and not notiable in idle.
If it turns out to be a valve, you need to replace it.
Good luck and let us know
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10-03-2011, 12:13 AM
#8
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Year: 1998
Model: Cherokee
Engine: I6
update.......did my leak down test and and it lead me to my valves..... was think of replacing just my valves but got a deal on a 0630 head ($256 shipped) took everything about and looked into my intake holes and intake valves on the bottom look like my exhaust valves
SO burnt valves was it. I'll let you no how it runs when its back together probly weds. or thurs. depending on ups.
SO burnt valves was it. I'll let you no how it runs when its back together probly weds. or thurs. depending on ups.
10-03-2011, 02:32 PM
#13
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Year: 1998
Model: Cherokee
Engine: I6
I'm not to sure it could have caused the blown gasket but i think this has been a long time issue. The po drove it every day with the jerking and loss of power but never wanted to fix it. So i cant be to sure
10-03-2011, 03:35 PM
#14
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Year: 1991
Model: Cherokee
Engine: 4.0 L
first question.....where in upstate you from? North of Syracuse?
second question.....blown gasket big problem with compression/leakdown results....
new head like you said you bought will alleviate many running problems.
just make sure all hoses vacuum grounds etc get put back on right an tight ya?
am sure once you have new head on, things will be sooo much smoother in the ride!
good luck sir!
cpnwrench
10-03-2011, 03:44 PM
#15
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Year: 1998
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Engine: I6
the new head will be great and i'm sure it will take care of all the problems .....i'm about two hours from the border of canada (upstate ny). The only thing that sucks is theres no place to wheel