why does my Ford F-150 12th Generation (2009-2014) engine misfire at idle

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, torque wrench, multimeter, fuel injector cleaner, and vacuum gauge.
• Ensure the vehicle is parked on a level surface with the parking brake engaged.

2. Replace Spark Plugs

• Step 1: Disconnect the negative battery terminal to prevent electrical shock.
• Step 2: Remove the ignition coils by unbolting them and disconnecting the electrical connectors.
• Step 3: Remove the old spark plugs using a spark plug socket. Inspect for wear and replace with new plugs (recommended gap: 0.054 inches).
• Step 4: Reinstall the ignition coils, ensuring they are securely bolted and the connectors are properly attached.

3. Inspect and Replace Ignition Coils (if necessary)

• Step 1: If misfire codes indicated issues with specific cylinders, remove the corresponding ignition coils.
• Step 2: Test each coil using a multimeter for primary and secondary resistance values according to OEM specifications. Replace any faulty coils.
• Step 3: Reinstall new or tested coils securely.

4. Clean Fuel Injectors

• Step 1: If injectors are suspected of being clogged, use a fuel injector cleaning kit following the manufacturer’s instructions.
• Step 2: Disconnect the fuel line from the injectors and connect the cleaning kit.
• Step 3: Run the cleaning solution through the fuel system as directed.

5. Check for Vacuum Leaks

• Step 1: With the engine running, use a vacuum gauge to check for normal levels (typically 17-21 inHg at idle).
• Step 2: If low readings are observed, inspect hoses and intake manifold for leaks, and replace any damaged components.