how to diagnose a Ford Explorer Fifth Generation (2011-2019) misfire

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the vehicle's battery to ensure safety while working on the ignition and fuel systems.

Tools Required:

• OBD-II scanner
• Spark plug socket and ratchet
• Torque wrench
• Fuel pressure gauge
• Compression tester
• Basic hand tools (sockets, wrenches)

2. Inspect and Replace Ignition Components

• Check Spark Plugs:

  1. Remove the spark plug wires or ignition coil packs.
  2. Use the spark plug socket to remove the spark plugs.
  3. Inspect the spark plugs for wear, carbon buildup, or damage.
  4. Replace any faulty spark plugs with new ones, ensuring the gap is set to manufacturer specifications (typically 0.054 inches).

• Check Ignition Coils:

  1. Inspect ignition coils for physical damage or cracks.
  2. Test each ignition coil with a multimeter following manufacturer specifications (usually around 0.4 to 0.5 ohms for primary resistance).
  3. Replace any faulty ignition coils with new OEM coils.

3. Fuel System Inspection

• Check Fuel Pressure:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "On" position without starting the engine to check for pressure. It should typically be around 30-45 psi.
  3. If pressure is low, inspect the fuel pump and fuel filter for blockages or failure.
  4. Replace the fuel filter if necessary and test the fuel pump operation.

4. Compression Testing

• Perform Compression Test:
  1. Remove all spark plugs to facilitate testing and prevent engine damage.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine for about 5 seconds and record the pressure reading.
  4. Repeat for all cylinders; readings should be within 10-15% of each other. Replace any cylinder with significantly lower compression.

5. Reassembly

• Reinstall all components in reverse order of removal, ensuring all connections are secure and torqued to specifications.
• Reconnect the battery.