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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket, dielectric grease.
• Remove the ignition coils by unfastening the bolts and disconnecting the electrical connectors.
• Use the spark plug socket to remove old spark plugs. Inspect for wear.
• Install new spark plugs, applying dielectric grease to the threads. Torque to manufacturer specifications (typically around 13-15 lb-ft).
• Reinstall ignition coils securely.

3. Test Ignition Coils

• Tools Required: Multimeter.
• Test each ignition coil's primary and secondary resistance using the multimeter, following the specifications in the service manual.
• Replace any faulty ignition coils.

4. Check Fuel System

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start) and check fuel pressure against manufacturer specifications.
• If pressure is low, inspect the fuel filter and fuel pump for issues.

5. Inspect for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• Use a smoke machine or carburetor cleaner around intake manifold gaskets, vacuum hoses, and throttle body.
• Look for changes in engine RPM indicating a vacuum leak and replace any affected hoses or gaskets.

6. Perform Compression Test

• Tools Required: Compression gauge.
• Remove spark plugs and insert the compression gauge into the cylinder.
• Crank the engine and record the pressure readings.
• Compare results to manufacturer specifications; low compression may indicate internal engine issues.