how to diagnose P0301 misfire code in Ford Mustang S550 (2015-2023)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 1 by unscrewing the retaining bolt and disconnecting the electrical connector.
  2. Remove the spark plug using a spark plug socket and ratchet.
  3. Inspect the spark plug for wear, carbon buildup, or damage. Replace with an OEM-spec spark plug if necessary.
  4. Torque the new spark plug to the manufacturer’s specification (typically around 13-15 ft-lbs).
  5. Reinstall the ignition coil and reconnect the electrical connector.

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is in good condition, test the ignition coil using a multimeter for proper resistance values.
  2. If the coil is faulty, remove it from the engine and replace it with a new OEM ignition coil.
  3. Reconnect the electrical connector and ensure it is secured.

4. Fuel Injector Inspection and Cleaning

• Sub-steps:
  1. Disconnect the fuel line from the injector and relieve fuel pressure by using a fuel pressure gauge.
  2. Remove the fuel injector from cylinder 1.
  3. Clean the injector using an appropriate injector cleaner or replace it if it is clogged or damaged.
  4. Reinstall the injector, ensuring proper seating and connection.

5. Compression Test

• Sub-steps:
  1. Remove the ignition coil and spark plug from cylinder 1.
  2. Insert a compression tester into the spark plug hole.
  3. Crank the engine for a few seconds and read the compression value. It should be within the manufacturer’s specified range (check service manual).
  4. If compression is low, further investigation into engine condition may be required (e.g., valve issues, head gasket failure).

6. Reconnect Battery and Check for Leaks

• Reconnect the negative battery terminal.
• Start the engine and check for leaks around the fuel lines and injectors.