2009 Jeep Wrangler Unlimited JKU ~77,000 miles P0304 Code

Описание: Misfire in the Jeep that has been dogging us for a couple months. CEL came on, so we replaced the spark plugs. Problem cleared up for a while, then returned. Rough idle then hesitation and bucking when accelerating in low RPMs. Then cleaned the throttle body and ran a couple cans of Techron through the gas tank thinking it might be clogged injectors. Had the entire throttle body cleaned and it went away, then returned. Bought coil pack and wire set from Jeep (recommended instead of crappy parts from autozone). Today I went to replace said parts and started the motor to warm it up so I had a warmer place to work on the street. Opened the hood to plan the replacement and heard what's in the video. I had never heard it before, but there the problem was as clear as day: some kind of arcing (either bad wires or the coil). Replaced both and voila! Idle as smooth as silk and acceleration problem solved. Also worth noting: rough running, poor idle and poor gas mileage is a clear indicator of dirty intake system. You can clean it yourself with throttle body cleaner (do NOT use carb cleaner - it is too harsh).

Tips:make sure to disconnect positive cable from battery; when disconnecting the coil you will need a flat head screwdriver to "unlock" the red lock tab on the coil driver wiring harness. Once it's unlocked just squeeze the tabs on top and wiggle it off; make sure to use some dialectric grease on all connections; OEM plug wires have cylinder numbers printed on them. If they don't, make sure to mark which wires go to which cylinders! When complete, take it easy when pulling out and take a test drive for a few miles as they engine will need to create a new map.