how to diagnose a misfire in my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Replace Spark Plugs

• Remove the engine cover (if applicable) using a socket set.
• Disconnect the ignition coils from the spark plugs.
• Remove the old spark plugs using a spark plug socket and ratchet.
• Check the gap on new spark plugs with a gauge, ensuring it meets manufacturer specifications (typically around 0.043 inches for this model).
• Install new spark plugs and torque them to the manufacturer-recommended specification (usually around 13 lb-ft).
• Reconnect the ignition coils and the engine cover.

3. Replace Faulty Ignition Coils

• If any ignition coils were identified as faulty, remove them by unbolting and disconnecting the wiring harness.
• Install new ignition coils, ensuring they click into place securely.
• Torque the bolts to manufacturer specifications (typically around 8 lb-ft).

4. Clean or Replace Fuel Injectors

• If fuel injectors are clogged, remove them carefully to avoid damage.
• Use a fuel injector cleaning kit to clean the injectors or replace them if severely damaged.
• Reinstall the cleaned or new injectors, ensuring proper alignment and connection.

5. Inspect and Repair Vacuum Leaks

• Check all vacuum hoses for cracks or disconnections.
• Replace any damaged hoses and ensure all connections are secure.