how to fix P0304 misfire code in Ford F-150 Fourteenth Generation (2021-present)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the ignition coil from cylinder 4 by unbolting it and disconnecting the electrical connector.
• Unscrew the spark plug using the socket set.
• Inspect the spark plug for wear or damage; replace if necessary.
• Install the new spark plug, tightening it to the manufacturer’s specified torque (typically around 13-15 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition, inspect the ignition coil for signs of damage or carbon tracking.
• If faulty, replace the ignition coil with a new one.
• Ensure it is properly seated onto the spark plug and reconnect the electrical connector.

4. Check Fuel Injector

• If misfire persists, inspect the fuel injector for cylinder 4.
• Disconnect the fuel injector connector and remove it from its mounting.
• Clean or replace the injector if clogged or damaged.
• Reattach the fuel injector and connector.

5. Verify Engine Compression

• If the misfire continues, perform a compression test on cylinder 4.
• If compression is below manufacturer's specifications, further engine diagnostics may be required to check for valve issues or piston problems.