why does my Toyota Camry's engine run rough when cold

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before proceeding.

2. Replace Coolant Temperature Sensor

• Locate the ECT sensor (usually near the thermostat housing).
• Disconnect the electrical connector from the sensor.
• Remove the sensor using a socket or wrench.
• Install the new ECT sensor, tightening it to the manufacturer's specified torque (typically around 15-20 ft-lbs).
• Reconnect the electrical connector.

3. Inspect and Replace Spark Plugs

• Remove the engine cover if necessary to access the spark plugs.
• Use a socket set to remove the spark plugs, inspecting them for wear or carbon buildup.
• Replace with new spark plugs as specified by the manufacturer (check for correct gap).
• Torque the new spark plugs to the specified value (usually around 13-16 ft-lbs).

4. Check for Vacuum Leaks

• Start the engine and use a spray bottle with soapy water around intake manifold and vacuum hoses.
• Look for bubbles indicating a leak; if found, replace the affected hoses or gaskets.
• Ensure all connections are tight.

5. Test and Replace Fuel Filter (if necessary)

• Relieve fuel system pressure using the service manual procedure.
• Locate and remove the fuel filter.
• Install the new fuel filter, ensuring correct orientation of the flow direction.
• Re-pressurize the fuel system and check for leaks.