how to fix the rough idle on my Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

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

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, gapping tool.
• Remove the ignition coils by unscrewing bolts and disconnecting electrical connectors.
• Carefully pull out the spark plugs using a socket wrench.
• Check the condition of the spark plugs; replace if worn or fouled.
• Gap the new spark plugs according to manufacturer specifications (usually around 0.044 inches for many Toyota models).
• Install new spark plugs and properly torque them to the recommended specification (typically around 13 lb-ft).
• Reinstall ignition coils and reconnect electrical connectors.

3. Clean Throttle Body

• Tools Required: Throttle body cleaner, soft cloth or brush.
• Disconnect the air intake duct from the throttle body.
• Spray throttle body cleaner into the throttle body while opening the throttle plate manually.
• Use a soft cloth or brush to remove any carbon buildup gently.
• Reattach the air intake duct securely.

4. Check and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, replacement vacuum hoses.
• Use a vacuum gauge to check for proper vacuum levels at idle.
• Inspect all vacuum lines for cracks or disconnections. Replace any damaged hoses.
• Ensure that all connections are secure and tight.

5. Test and Replace Fuel Filter

• Tools Required: Fuel pressure gauge, wrench set.
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition on (without starting the engine) to check for proper fuel pressure.
• If pressure readings are low, replace the fuel filter according to manufacturer specifications.