deloxx
NAXJA Forum User
- Location
- Massachusetts
Hello all, I have a 1998 Cherokee 4.0 5spd 4x4. I suddenly developed a cylinder #1 misfire and I am having a hell of a time finding the cause. I can feel the misfire at idle, hear it in the exhaust, and am receiving a P0301 code. The following have been tested and accounted for:
I also have another 98 cherokee/comanche build going on, so I have access to whatever parts for comparison/testing. I will be trying the PCM off of that one tomorrow, though it is an automatic.
I have no idea what else to try.
- Compression: #1 150psi #2 165 #3 170 #4 150 #5 160 #6 180 (all normal an within spec)
- Confirmed spark, also replaced rotor, dist. cap, wires, and plugs to be sure.
- Ground resistance of installed spark plug is 0.3 ohms, equal to others
- Tested injector wiring with a noid light, functions normal. Also tested voltage (14v running) and equal resistance to other cylinders wiring.
- Swapped injector with other cylinders, no change.
- Ran fuel rail removed from manifold, all 6 spraying equally
- Fuel pressure normal, 48psi idle
- Normal vacuum, 21in/hg at idle
- Mopar crank position sensor installed last year as preventative maintenance
- Cleaned connector c107 at the suggestion of another thread
- cleaned alternator grounds at the suggestion of another thread
- Removed valve cover and measured valve travel, intake and exhaust valves on #1 move equal to other cylinders
- No intake manifold leak detectable (carb cleaner spray method)
- Have run seafoam through the intake and MMO hot soak in the cylinder overnight, no effect.
I also have another 98 cherokee/comanche build going on, so I have access to whatever parts for comparison/testing. I will be trying the PCM off of that one tomorrow, though it is an automatic.
I have no idea what else to try.