my Toyota RAV4 has a rough idle when cold, what's causing it

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery to prevent any electrical issues.

2. Inspect and Replace Spark Plugs

• Remove the engine cover if applicable.
• Use a socket set to unbolt the ignition coils and remove them.
• Extract the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear or carbon buildup; replace with OEM or equivalent parts as needed.
• Reinstall the spark plugs, tightening them to the manufacturer's torque specifications (typically around 13-15 ft-lbs).
• Reattach the ignition coils and engine cover.

3. Clean the Throttle Body

• Remove the air intake hose connected to the throttle body.
• Use throttle body cleaner and a clean cloth to remove carbon deposits from the throttle body and plate.
• Ensure that the throttle plate moves freely.
• Reattach the air intake hose securely.

4. Inspect and Replace Fuel Filter (if necessary)

• Locate the fuel filter, typically found along the fuel line.
• Relieve fuel system pressure by removing the fuel pump fuse and starting the engine until it stalls.
• Disconnect fuel lines from the filter using a line disconnect tool.
• Install the new fuel filter in the correct orientation (arrow indicating flow direction).
• Reconnect fuel lines and replace the fuse.

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

• Locate the engine coolant temperature sensor.
• Disconnect the electrical connector and remove the sensor using a socket or wrench.
• Install the new sensor and reconnect the electrical connector.