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Unread 10-10-2010, 07:46 PM   #1
jpoleto
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Join Date: Oct 2010
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Wj 2001 GC misfire

While driving on the highway, my 2001 grand cherokee laredo started to shake and shudder. I pulled the codes and it came up with a P0302 error, which I looked up and found to be a 2nd cylinder misfire.
I got the jeep used in 2004, and had not changed any of the spark plugs. It has 164,000 miles on it, so I figured it was probably just a faulty plug. I changed all 6 out for new ones, and the 2nd cylinder plug was pretty beaten up.
Here's the problem: The engine still misfires. It seems to be the worst when the engine is at about 1800rpm, so it's possible to avoid violently shaking the car, but going uphill at high speeds seems to strain the engine.
The oil level and engine temp are fine, as is the oil pressure. I'd like to figure out what's wrong without having to take it in to the shop. I'm thinking it could be something in the fuel line, or something with the coil over the 2nd cylinder.

Anyone have experience fixing this problem?
-John

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Unread 10-10-2010, 08:00 PM   #2
SplitNail
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possibly the coil. Thats my bet
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Unread 10-10-2010, 08:08 PM   #3
inlinegrand6
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V8 or 4.0 , if its a v8 do a coil swap if the misfires change to a different cylinder its the coil pack. 4.0 try to test with a different rail if available or buy a new one. post if problem exists thanks
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Unread 10-11-2010, 01:54 AM   #4
Kramer H
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Quote:
Originally Posted by inlinegrand6 View Post
V8 or 4.0 , if its a v8 do a coil swap if the misfires change to a different cylinder its the coil pack. 4.0 try to test with a different rail if available or buy a new one. post if problem exists thanks
he said all six plugs, so im hoping that means he has a 4 liter, if not i think i found his misfire its more than likely a coil pack, but too bad for you 4liter guys, its all on one rail. us 4.7's are individual.
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Unread 10-11-2010, 06:23 AM   #5
jpoleto
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It's a 4 liter, so all 6 coils are on the rail.... which is why i was hoping it wasn't a coil haha.. I'm not familiar with the jeep COP system, is there a way i can check the coils with a multimeter? I'd rather know that it's a coil before taking the whole rail out, that thing sits under both radiator lines and a mess of other stuff.
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