how to diagnose a misfire in my Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts needed 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 shorts.

2. Replace Spark Plugs

• Remove the engine cover if applicable (using a socket set).
• Disconnect the ignition coil connectors.
• Remove the ignition coils (unbolt and pull straight out).
• Use a spark plug socket to remove the old spark plugs.
• Inspect and gap new spark plugs according to manufacturer specifications.
• Install new spark plugs and torque them to the specified value (usually around 13-16 lb-ft).
• Reinstall the ignition coils and reconnect the connectors.

3. Inspect and Replace Ignition Coils (if necessary)

• If ignition coils were found faulty during diagnostics, replace them.
• Remove the faulty coil(s) and install new ones, ensuring they are seated properly.
• Reconnect the ignition connectors.

4. Clean or Replace Fuel Injectors (if necessary)

• If injectors are clogged, use a fuel injector cleaner or replace them.
• Remove the fuel rail as per the service manual.
• Replace or clean the fuel injectors and reinstall the fuel rail.

5. Fix Vacuum Leaks

• Inspect all vacuum hoses and the intake manifold for any cracks or loose connections.
• Replace any damaged hoses or gaskets.