I have a 2001 Jeep Cherokee with 97k miles. The engine keeps misfire in cylinder 6 when going into high rev(overtaking cars on interstate). I have replaced the ignition coil pack and the fuel injector and replaced all 6 spark plugs 2 months ago. I really don’t know what else would cause a misfire.
“ignition coil pack and the fuel injector and replaced all 6 spark plugs”
- spark plug wires?
Presumably you have a code - something like P0306? Any other codes?
Check the compression - look esp. at #6
I’d get a new fuel filter on it and check the fuel pressure under load - preferably with a gauge hooked up while driving.
There is no spark plug wires, cap, rotor on this 4.0 6 cylinder. Ignition system is a coil pack that stretches the across all 6 spark plugs. From what I am seeing there is no fuel filter underneath the jeep in the frame rail like older Cherokees. I am assuming the filter is stuck in the fuel tank along the fuel pick-up. the fault code is p306 and I also failed to mention there is a rough idle.
Perform a compression test.
So, without details on code 306, is the injector dirty or clogged? Could also be any number of aggravating sensors that tell your coil packs when to fire; or even a vacuum leak. Just a few thoughts.
pull the # 6 spark plug and 2 others, compare the plugs. Is number 6 black and wet looking-oil fouling, is it dry and black- carbon- could be caused by the misfire, or is it the color of your antifreeze- head gasket, cracked head or block, or in some cases-bad intake manifold or gasket.