my BMW X3 G01 (2018-2024) has a rough idle when cold starting

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to ensure safety when working with electrical components.
• Allow the engine to cool down before proceeding with any work.

2. Clean Throttle Body

• Sub-steps:

  1. Remove the air intake duct connected to the throttle body.
  2. Use throttle body cleaner and a soft cloth to clean the throttle plate and surrounding area.
  3. Reattach the air intake duct securely.

• Tools Required:

  • Throttle body cleaner
  • Soft cloth
  • Screwdriver set

3. Replace Spark Plugs

• Sub-steps:

  1. Remove the ignition coil covers (if applicable) to access the spark plugs.
  2. Unscrew and remove the old spark plugs using a spark plug socket.
  3. Inspect the spark plug gap and replace with new plugs if necessary (check specifications for gap size).
  4. Install new spark plugs and torque them to manufacturer specifications.

• Tools Required:

  • Spark plug socket
  • Torque wrench

4. Test Fuel Pressure

• Sub-steps:

  1. Connect a fuel pressure gauge to the fuel rail's test port.
  2. Turn the ignition to the "ON" position (do not start) to check pressure reading.
  3. Compare the reading to the manufacturer's specifications; replace the fuel pump if below specifications.

• Tools Required:

  • Fuel pressure gauge

5. Verify Coolant Temperature Sensor

• Sub-steps:

  1. Locate the coolant temperature sensor and disconnect the wiring harness.
  2. Using a multimeter, check the resistance against the specifications provided in the service manual.
  3. Replace the sensor if readings are out of specification.

• Tools Required:

  • Multimeter