Reasons for Detected Misfire in Cylinder 4 (P0304)

[Evangeline]

p0304 detected misfire in cylinder 4 can be caused by the following reasons: 1. Spark Plug: Poor spark plug firing. 2. Piston Ring: Damaged piston rings leading to low cylinder pressure. 3. Ignition Coil: Internal damage to the ignition coil. 4. Timing Mechanism: Incorrect timing or skipped teeth in the timing mechanism. 5. Engine: Engine computer damage or fault code issues. The troubleshooting methods are: Check the cylinder pressure of each cylinder to ensure it is normal; most vehicles have a cylinder pressure of around 1300 kPa. Address any cylinders with abnormal pressure. Inspect the spark plug firing condition, the size of the free gap, whether the ceramic area has cracks, and if it has been punctured. Replace any damaged spark plugs. Check if the timing marks on the timing belt or timing chain align correctly. If misaligned, disassemble the timing mechanism and realign the timing marks. Try replacing the ignition coil to see if the issue is resolved.