how to diagnose rough idle in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, fuel pressure gauge, vacuum gauge
• Disconnect the battery to ensure safety while working on electrical components.

2. Replace Spark Plugs

• Remove the engine cover if applicable.
• Disconnect the ignition coils and unscrew them using a socket.
• Remove old spark plugs using a spark plug socket.
• Install new spark plugs to the manufacturer’s torque specifications (typically 13-15 ft-lbs).
• Reconnect the ignition coils and engine cover.

3. Clean or Replace the Throttle Body

• Remove the intake duct connected to the throttle body.
• Use a throttle body cleaner and a soft cloth to clean the throttle body.
• If heavily carbonized, consider removing it for a more thorough cleaning.
• Reattach the intake duct securely.

4. Inspect and Replace Fuel Filter

• Locate the fuel filter (often integrated into the fuel pump assembly).
• Relieve the fuel pressure by removing the fuel pump fuse and starting the engine until it stalls.
• Disconnect the fuel lines (use proper safety precautions).
• Replace the fuel filter with a new one and reconnect the fuel lines securely.

5. Fix Vacuum Leaks

• Inspect all vacuum lines connected to the intake manifold.
• Replace any damaged or cracked vacuum hoses.
• Use a vacuum gauge to check for proper readings after repairs.