why does my Toyota RAV4 XA40 (2013-2018) have a rough idle when cold

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge.
• Allow the engine to cool completely before beginning work.
• Disconnect the negative battery terminal for safety.

2. Inspect and Replace Spark Plugs

• Remove the ignition coil cover if applicable.
• Disconnect the ignition coils from the spark plugs.
• Using a socket set, remove the spark plugs.
• Inspect the spark plugs for wear and replace them if necessary (specify the gap and part number if needed).
• Reinstall new spark plugs and reconnect ignition coils, ensuring they are seated properly.

3. Check and Clean the Air Intake System

• Remove the air intake duct and inspect the air filter for dirt or blockages; replace if necessary.
• Clean the throttle body using throttle body cleaner to remove any carbon buildup that could affect air intake.
• Reassemble the air intake system securely.

4. Test and Replace the Engine Coolant Temperature Sensor (if necessary)

• Locate the engine coolant temperature sensor by referring to the service manual.
• Use a multimeter to check the sensor's resistance against the specifications in the manual.
• If the readings are out of spec, remove the sensor and replace it with a new one, ensuring proper sealing.

5. Verify Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start the engine) and check the fuel pressure reading.
• Compare the reading with the manufacturer's specifications; replace the fuel pump if the pressure is low.