why does my BMW 5 Series F10/F11 (2010-2017) have a rough idle when cold

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to prevent electrical short circuits.
• Allow the engine to cool before beginning work.

2. Inspect and Clean the Throttle Body

• Remove the air intake duct to gain access to the throttle body.
• Use throttle body cleaner and a soft cloth to clean the throttle plate and surrounding area.
• Reattach the air intake duct securely.

3. Replace Spark Plugs

• Remove the ignition coils by unscrewing the retaining bolts.
• Carefully pull out the coils and disconnect the electrical connectors.
• Remove old spark plugs using a spark plug socket and ratchet.
• Install new spark plugs, ensuring they are gapped correctly to manufacturer specifications (typically around 0.028-0.032 inches for BMW).
• Reinstall ignition coils and secure them with bolts.

4. Replace Engine Coolant Temperature Sensor

• Locate the coolant temperature sensor on the engine block.
• Disconnect the electrical connector and remove any retaining clips.
• Unscrew the sensor using a socket wrench and replace it with a new one.
• Reconnect the electrical connector and ensure it is secure.

5. Verify Fuel Pressure

• Attach a fuel pressure gauge to the fuel rail.
• Start the engine and observe the pressure reading; it should meet manufacturer specifications (usually around 50-60 psi).
• If pressure is low, inspect the fuel pump and fuel filter for issues.