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Old 04-02-2013, 07:31 PM   #1
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Exclamation Dreaded Misfire... JEEP GURUS PLEASE HELP! *READ*

Okay, so ive had a misfire in my engine for a little while, ive just been putting it off because i didnt have a need to drive my Jeep for a while. Today i decided to try and conquer the problem. My codes are as follows.
P0300 random misfire
P0302 Misfire in cylinder 2
P0304 Misfire in cylinder 4
P0306 Misfire in cylinder 6

I automatically assumed it was plugs, so i got new plugs and threw them in.. didnt fix it.
So i went all out and did a full diagnostic for Fuel, Fire, and Compression.
Fuel: I took my DMM to my injector wiring and got the following:
Cylinder 1 - 11.92ohms
Cylinder 2 - 11.87ohms
Cylinder 3 - 11.98ohms
Cylinder 4 - 11.95ohms
Cylinder 5 - 11.97ohms
Cylinder 6 - 12.00ohms

Everything is within spec and looks good, nothing really stood out.

Fire: I changed the old plugs for some OE spec plugs.

Next i tried switching the boots on the coil rail (ive read that this might fix or rather point out the problem) That didnt do anything.

Compression: I tested each cylinder letting it turn over 5 times on each. My results follow:
Cylinder 1 - 152psi
Cylinder 2 - 153psi
Cylinder 3 - 155psi
Cylinder 4 - 150psi
Cylinder 5 - 154psi
Cylinder 6 - 156psi

Nothing weird or standing out here!

Does anyone have any idea what it could be? O2 sensor? camshaft position sensor? any ideas at all are welcome and GREATLY appreciated. I am stumped.

Oh yea, I own a 2003 TJ with the I6 4.0 AMC based engine

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Old 04-02-2013, 07:34 PM   #2
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Quote:
Originally Posted by Jwolfer View Post
I was getting random misfire codes and new O2 sensors fixed the problem for me.
I was thinking it might be the O2 sensor...

Quote:
Originally Posted by _plaisance View Post
possibly your distributor going to your plugs is there any spark???
I have the coil rail. and yea, i have spark

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Old 04-02-2013, 07:36 PM   #3
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*bump*
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Old 04-03-2013, 03:33 PM   #4
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bump
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Old 04-03-2013, 04:10 PM   #5
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I keep saying this in all the other misfire threads, but I've had your problems and the fix was upgrading my injectors. I'm not saying that will fix it for you, but that's what did it for me!
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Old 04-03-2013, 04:18 PM   #6
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I wish it would, but I dont wanna throw money at a problem and it not be fixed... I dont have any money, I own a Jeep! :P
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Old 04-03-2013, 04:44 PM   #7
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Why don't you clean and rebuild the injectors you have then?

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