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