why is my Toyota Highlander XU70 (2020-Present) engine misfiring

Solution

1. Preparation

• Disconnect the battery to ensure safety.
• Gather tools: OBD-II scanner, socket set, torque wrench, multimeter, and vacuum gauge.

2. Inspect Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Use a socket wrench to carefully remove each spark plug.
  3. Inspect the spark plugs for wear, fouling, or improper gap.
  4. Replace any defective spark plugs with OEM equivalent parts.
  5. Torque new spark plugs to manufacturer specifications (typically around 13 lb-ft).

3. Check Ignition Coils

• Sub-steps:
  1. Disconnect the electrical connectors from the ignition coils.
  2. Remove the ignition coils using a socket wrench.
  3. Test each ignition coil with a multimeter for proper resistance (refer to specifications in the service manual).
  4. Replace any faulty ignition coils with OEM parts.
  5. Reinstall ignition coils and reconnect electrical connectors.

4. Inspect Fuel Injectors

• Sub-steps:
  1. Remove the intake manifold if necessary to access fuel injectors.
  2. Check for clogging or leaks by visually inspecting injectors.
  3. Use a fuel injector cleaning kit to clean injectors if clogged.
  4. Replace any defective fuel injectors with OEM replacements.
  5. Reassemble the intake manifold with new gaskets as needed.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Start the engine and use a vacuum gauge to check idle vacuum.
  2. Spray soapy water around intake manifold gaskets and vacuum hoses to check for leaks.
  3. Address any leaks by replacing gaskets or hoses as necessary.
  4. Clear any stored error codes from the OBD-II scanner after repairs.