why does my BMW X3 F25 (2011-2018) have a rough idle when cold

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool completely before starting work.

2. Inspect and Clean Air Intake System

• Remove the air intake duct leading to the throttle body.
• Inspect the MAF sensor for dirt and clean it with MAF cleaner.
• Check the air filter; replace if dirty.
• Reinstall the air intake duct securely.

3. Test and Replace Spark Plugs

• Remove the ignition coils by unbolting them and pulling them out of the spark plug well.
• Remove the spark plugs using a spark plug socket and inspect them for wear or fouling.
• Replace with new spark plugs if necessary, ensuring they are gapped correctly according to manufacturer specifications.
• Reinstall the ignition coils and ensure they are seated correctly.

4. Clean Throttle Body

• Remove the throttle body from the intake manifold by unbolting it.
• Clean the throttle plate and interior with throttle body cleaner and a soft cloth.
• Reinstall the throttle body, ensuring to torque bolts to manufacturer specifications.

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

• Locate the coolant temperature sensor and disconnect the electrical connector.
• Remove the sensor using a socket or wrench.
• Install a new sensor, ensuring not to overtighten, and reconnect the electrical connector.