how to fix rough idle in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before working on components.

2. Clean Throttle Body

• Tools Required: Throttle body cleaner, soft cloth, socket set.
• Remove the air intake duct to access the throttle body.
• Spray throttle body cleaner onto the throttle plate and use a soft cloth to wipe away any carbon deposits.
• Ensure the throttle plate moves freely, then reassemble the intake duct.

3. Replace Spark Plugs

• Tools Required: Socket set, torque wrench.
• Remove the ignition coils by disconnecting the electrical connectors and unbolting them.
• Take out the old spark plugs using a spark plug socket.
• Install new spark plugs, ensuring they are gapped to the manufacturer's specifications.
• Reinstall the ignition coils and reconnect the electrical connectors.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge, safety goggles.
• Locate the fuel rail and attach the fuel pressure gauge.
• Turn the ignition key to the "ON" position (do not start the engine) to check pressure readings.
• If the pressure is below specifications, consider replacing the fuel pump or filter.

5. Inspect for Vacuum Leaks

• Tools Required: Smoke machine (optional) or propane torch.
• Visually inspect vacuum hoses for cracks or disconnections.
• Use a smoke machine to introduce smoke into the intake system, or carefully use a propane torch around hoses and joints to listen for changes in idle.