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 tools and parts required for the repair.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery to ensure safety during the repair.

2. Replace Spark Plug

• Remove the ignition coil from cylinder four by unscrewing the retaining bolt and gently pulling it off.
• Using a spark plug socket, remove the old spark plug from cylinder four.
• Inspect the new spark plug and ensure it is gapped correctly according to manufacturer specifications.
• Install the new spark plug and torque it to the recommended specification (typically around 13 ft-lbs).
• Reattach the ignition coil and secure it with the retaining bolt.

3. Inspect and Replace Ignition Coil (if necessary)

• If the ignition coil shows signs of damage, replace it with a new one.
• Remove the coil from the other cylinders if needed to ensure the replacement matches.
• Install the new ignition coil on cylinder four, ensuring a secure fit.

4. Check and Clean Fuel Injector

• Disconnect the fuel injector connector for cylinder four.
• Remove the fuel rail if required to access the injector.
• Test the injector using a multimeter to ensure it's operating correctly.
• If clogged, clean the injector using an appropriate cleaner or replace it with a new injector.

5. Perform Compression Test (if necessary)

• Remove the spark plug from cylinder four.
• Insert a compression gauge into the spark plug hole and crank the engine.
• Record the compression reading; it should meet manufacturer specifications (usually around 120-200 psi).
• If low, further diagnosis may be needed for internal engine issues.