- Mar 20, 2018
- v-6 pre-pentastar
So my JK, original owner well maintained, has an engine misfire on #5, not around town (Southern Cal.) but after driving it down the freeway for 30 miles or so. It burps, hesitates, backfires occasionally , once through the intake during deceleration. 123K miles, have replaced the coil twice already in the past, each time verifying by doing a resistance test on the coil, one bank was weak coinciding with that misfire. This coil that is 30K miles old checks with the same resistance values as a new one at the store, I checked them both. Plugs and wires 30K miles old. Pulled plugs on drivers side of engine, visual and ohm and the plugs look good, swapped wires around the cylinder and no misfire. Suggested I allow an air gap where the coil mounts to it's plate, installed new crankshaft positioning sensor. Around town it's fine, get her toasty and she barks. Oil is clean, coolant is clean, trans was serviced at 100K. Garage kept, non smoker non abuser of my jeep out in the desert. Heat seems to be breaking something down, what though.