Consistent misfire - cylinder 4 only

smash_lizard

New Member
Joined
Aug 20, 2019
Messages
13
Location
Raleigh, NC
2002 2.5L. Headgasket/head rebuilt July 2019.

Since wheeling season around here ended in December the jeep has been sitting on its trailer and only been started once in February. At that time there were no issues and it ran normally. This past weekend it was pulled off the trailer in preparation for an upcoming Windrock trip and much to my dismay it is not firing on cylinder 4. I may be mistaken but this misfire occured only after the exterior and frame were pressure washed.

We have spark (visual observation with plug pulled) air, and fuel (pressure is good) but still no ignition in cylinder four. We did a pressure test this evening and got 190psi. The distributor cap got replaced as moisture was suspect and cylinder 4's fuel injector was replaced as good compression pointed us in direction of fuel.

The thing that has us stumped is that it is unique to cylinder 4. Any ideas? Thank you in advance.

Edit: the engine appears to be running normally on there cylinders. No hesitation, nothing out if the ordinary.
 
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Completely remove the spark plug wire for #4 and measure the ohms resistance then compare to the other plug wires.
You should try cranking the engine over in the dark and see if the spark is arcing to ground on #4 cylinder.
 
Completely remove the spark plug wire for #4 and measure the ohms resistance then compare to the other plug wires.
You should try cranking the engine over in the dark and see if the spark is arcing to ground on #4 cylinder.

I'll give that a try tomorrow. Just for kicks I swapped the spark plugs between 3 and 4 and noticed when I pulled 3's spark plug it did appear slightly where as 4's did not.

Also, along with P0304 I had P0320 yesterday as well. I say had because they have been cleared. I am by no means a mechanic so hopefully I am phrasing things correctly.
 
Did a leak down test today, not looking good.
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