how to diagnose a misfire in my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface, and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shocks.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the ignition coil covers if applicable.
  2. Unplug the ignition coils and remove them using a socket set.
  3. Remove the old spark plugs with a spark plug socket and inspect for wear.
  4. Install new spark plugs, ensuring the correct gap (0.043 in for Toyota engines).
  5. Reinstall ignition coils, ensuring they are securely connected.

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. Remove the ignition coils as mentioned above.
  2. Test each coil with a multimeter (should show manufacturer-specified resistance).
  3. Replace any faulty ignition coils with new ones.
  4. Reinstall the ignition coils and covers.

4. Clean or Replace Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail and disconnect fuel lines (use caution due to pressure).
  2. Clean the fuel injectors using a dedicated injector cleaning kit or replace them if necessary.
  3. Reinstall the fuel rail and ensure all connections are secure.

5. Perform Compression Test (if necessary)

• Sub-steps:
  1. Remove spark plugs to allow access to cylinders.
  2. Insert a compression gauge into the spark plug hole.
  3. Crank the engine to take readings and compare with manufacturer specifications.
  4. Address any cylinders with low compression (possible head gasket issues).