how to diagnose P0302 misfire code on Ford F-150 12th Generation (2009-2014)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, compression tester, smoke machine (optional).
• Disconnect the negative battery terminal to ensure safety while working on the vehicle.

2. Replace Spark Plug and Coil (if necessary)

• Sub-steps:
  1. Remove the ignition coil from cylinder 2 using a socket wrench.
  2. Remove the spark plug with a spark plug socket.
  3. Inspect the spark plug for wear; replace it if it shows signs of fouling or excessive wear.
  4. Install a new spark plug and torque it to the manufacturer's specifications (typically around 13-15 lb-ft).
  5. If the ignition coil is faulty, replace it with a new one, ensuring proper fit and connection.

3. Test and Replace Fuel Injector (if necessary)

• Sub-steps:
  1. Disconnect the fuel injector connector from cylinder 2.
  2. Check the resistance of the injector using a multimeter; it should generally be between 12-16 ohms.
  3. If the injector is out of specification, remove it using a socket and replace it with a new one.
  4. Reconnect the injector and ensure all connections are secure.

4. Perform Compression Test (if misfire persists)

• Sub-steps:
  1. Remove the spark plugs from all cylinders for accurate testing.
  2. Insert the compression tester into the spark plug hole of cylinder 2.
  3. Crank the engine several times and record the compression reading.
  4. Compare the reading to the specifications (usually around 130-160 psi for this engine).
  5. If the compression is low, further investigation is required to determine if it's a valve, head gasket, or piston issue.