how to diagnose P0301 misfire on my Ford F-150 14th Generation (2021-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression gauge, noid light.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

• Remove the engine cover if necessary for access.
• Disconnect the ignition coil connector from the spark plug.
• Remove the ignition coil by unscrewing it and gently pulling it out.
• Using a socket, remove the spark plug from cylinder 1.
• Inspect the old spark plug for wear; replace with a new spark plug with the correct specifications (refer to the owner’s manual for gap and type).
• Install the new spark plug and torque it to the manufacturer’s specifications (typically 12-15 lb-ft).
• Reinstall the ignition coil and reconnect the connector.

3. Replace Ignition Coil (if needed)

• If the ignition coil is found to be faulty during testing, remove the ignition coil as detailed in the previous step.
• Install a new ignition coil and torque it to the specified value (usually around 8-10 lb-ft).
• Reconnect the electrical connector to the new ignition coil.

4. Test Fuel Injector

• If the fuel injector is suspected to be faulty, remove the injector connector from cylinder 1.
• Use a noid light to check for proper signal; if the light does not flash, there may be an issue with the wiring or the engine control unit (ECU).
• If the injector fails the test, remove it and replace it with a new one, ensuring proper seating and connection.

5. Perform Compression Test

• If previous steps do not resolve the misfire, conduct a compression test.
• Remove the spark plug from cylinder 1.
• Install the compression gauge into the spark plug hole.
• Crank the engine for a few seconds and record the compression reading.
• Compare the reading to specifications (typically around 120-160 psi). Low compression indicates possible internal engine issues.