how to fix P0300 code on Ford Mustang S550 (2015-2023) for random misfires?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coils from the spark plugs.
  3. Using a spark plug socket, remove the old spark plugs.
  4. Inspect the old plugs for signs of wear or fouling.
  5. Install new spark plugs with the correct gap (typically 0.030 inches for most Mustangs).
  6. Reconnect the ignition coils and replace any covers.

Tools Required: Spark plug socket, torque wrench, gap gauge.

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. Remove the ignition coils from the engine.
  2. Check for cracks or damage on the coils.
  3. Replace any faulty ignition coils with new ones.
  4. Reinstall the ignition coils securely.

Tools Required: Ratchet, socket set.

4. Check for Vacuum Leaks

• Sub-steps:
  1. Inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or propane to locate leaks around the intake manifold.
  3. Replace any damaged hoses or tighten loose connections.

Tools Required: Smoke machine or propane torch (for testing).

5. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition on (do not start) to check the pressure reading.
  3. Compare the reading with the manufacturer specifications (typically 40-60 psi).
  4. If pressure is low, inspect the fuel pump and fuel filter.

Tools Required: Fuel pressure gauge.

6. Clean or Replace Fuel Injectors

• Sub-steps:
  1. Remove the fuel injectors from the fuel rail.
  2. Inspect for clogs or debris—clean using a specialized injector cleaner if necessary.
  3. If cleaning does not resolve the issue, replace the fuel injectors.

Tools Required: Injector puller, cleaning kit.