number six cylinder code 0306

[Scott Dog]

My son's wrangler is giving him MORE problems. Check engine light came on, and starting running very rough. It is code p0306, misfire in cylinder 6. We pulled the plugs, look fine, cap and rotor need replaced, but look ok for now. It has a knocking noise at the back of motor, (cylinder 6) when it is reved up at high rpm. Pulled the dipstick, and there is too much oil on stick, and it smells of fuel. Any suggestions? we were thinking fuel injector, rocker arm, push rod? Thanks for any information!!

[danielsatur]

Check the compression on cyline 6.

[CJ0717]

Agree on checking the compression on Cyl 6. The knock could be a late detonation. If compression ok could be a spark plug wire issue or coil. Separate coil pack per cyl or is the coil pack common with other cylinders?

CJ

Edit: Fuel in the oil may be from no detonation not necessarily from a blown piston ring. Have you verified proper spark on the #6 spark plug?

[Scott Dog]

i changed to plugs, wires, distributor cap, and rotor button, seemed to help a little bit but as soon as the jeep warmed up it got worse but not as bad as it was prior to the new parts. haven't really had time to check compression yet but will do, the knocking is only really noticeable when rev'd to around 2,000 rpm's or higher, i also tried removing the injector pig tail from the injector while the jeep was running, it sputter a little bit worse but not enough to stall the motor or make it run much worse. any more suggestions would be much appreciated!!

[fredjacksonsan]

What year and how many miles?

[fredjacksonsan]

What year and how many miles?

[Scott Dog]

1999 wrangler sport, 4.0L, 125,000 miles, i just noticed a white film on the inside of the radiator cap, and upon tasing it, it was very sweet, so maybe a blown headgasket, but i hope not

[Scott Dog]

oil cap, not radiator cap, sorry.

[CJ0717]

Have you checked compression yet on Cyl 6? Check a couple of other cylinders for comparison. 6 should be distinctly lower if the rings or gasket are shot. The reason for comparing to a couple others is that with that many miles the compression may not be up to the manufacturers specs on any cylinder so a comparison will weed out the problem cyl.