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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a flat surface, and the engine is turned off and cool.
• Disconnect the negative battery terminal to prevent any electrical short circuits.

2. Clean the Throttle Body

• Remove the air intake duct connected to the throttle body.
• Use a throttle body cleaner and a soft cloth to clean the throttle plate and surrounding areas.
• Reinstall the air intake duct securely.

3. Replace Spark Plugs

• Remove the ignition coils by unbolting them from the engine.
• Disconnect the electrical connectors from each ignition coil.
• Remove the old spark plugs using a spark plug socket and ratchet.
• Install new spark plugs, ensuring they are gapped correctly (0.043 inches).
• Reinstall the ignition coils and reconnect the electrical connectors.

4. Inspect and Repair Vacuum Leaks

• Visually inspect all vacuum lines for cracks or disconnections; replace any damaged hoses.
• Use a smoke machine to find any hidden leaks if necessary.
• Ensure the intake manifold is properly sealed and bolted down.

5. Fuel System Inspection

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition on (do not start) and check the fuel pressure; it should be within the manufacturer’s specification (around 50-60 psi).
• If the pressure is low, inspect the fuel pump, filter, and regulator for issues.