how to diagnose P0302 misfire code in Ford F-150 14th Generation (2021-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, multimeter, compression tester, noid light.
• Ensure the vehicle is on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Spark Plug Replacement

• Remove the spark plug using a socket wrench.
  • Sub-steps:
    1. Clean the area around the spark plug to prevent debris from entering the cylinder.
    2. Use a spark plug socket to carefully unscrew and remove the spark plug.
    3. Inspect the removed spark plug for wear or damage.
• Install a new spark plug with the correct gap (0.030 inches).
  • Sub-steps:
    1. Apply anti-seize compound to the threads of the new spark plug.
    2. Insert the new spark plug and tighten to manufacturer specifications (typically 13-15 lb-ft).
    3. Reconnect the ignition coil to the spark plug.

3. Ignition Coil Testing and Replacement

• Test or replace the ignition coil for cylinder 2.
  • Sub-steps:
    1. Disconnect the electrical connector from the ignition coil.
    2. Use a multimeter to check the primary and secondary resistance according to manufacturer specifications.
    3. If the coil is faulty, remove it using a socket and replace it with a new one, ensuring the connection is secure.

4. Fuel Injector Testing and Cleaning

• Check the operation of the fuel injector for cylinder 2.
  • Sub-steps:
    1. Disconnect the fuel injector connector.
    2. Use a noid light to verify if the injector is receiving a signal.
    3. If no signal is detected, inspect wiring and connectors; repair as necessary.
    4. If the injector is faulty, remove and replace it with a new one.

5. Compression Testing (if necessary)

• If misfire persists, perform a compression test on cylinder 2.
  • Sub-steps:
    1. Remove the spark plug and throttle body (if required).
    2. Insert the compression tester into the spark plug hole.
    3. Crank the engine and record the compression reading. Compare with specifications (approximately 120-160 psi).
    4. If the compression is low, further diagnose for potential internal engine issues.