why does my BMW 3 Series F30/F31 (2012-2019) engine misfire at idle

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to ensure safety during repair.
• Allow the engine to cool before beginning work.

2. Inspect and Replace Spark Plugs

• Remove the ignition coil cover if applicable.
• Use a socket set to remove the spark plugs.
• Inspect the spark plugs for fouling, wear, or damage.
• Replace with new OEM or equivalent spark plugs, ensuring the correct gap.
• Torque the spark plugs to manufacturer specifications (typically around 15-20 Nm).

3. Check and Replace Ignition Coils

• If spark plugs are in good condition, proceed to inspect ignition coils.
• Disconnect the electrical connector from each ignition coil.
• Remove the ignition coils using a socket or ratchet.
• Test each ignition coil with a multimeter for resistance; replace any faulty coils.
• Reinstall new ignition coils, ensuring they are seated properly.

4. Verify Fuel System

• Use a fuel pressure gauge to check the fuel pressure; it should meet OEM specifications (typically around 50-60 psi).
• If pressure is low, check the fuel filter and fuel pump for blockages or failure.
• Replace the fuel filter if clogged, and consider replacing the fuel pump if it fails to deliver adequate pressure.

5. Inspect Air Intake and Vacuum System

• Check for any obstructions or leaks in the air intake system, including the air filter and intake ducts.
• Inspect all vacuum hoses for cracks or disconnections; replace any damaged hoses.
• Clean the throttle body if necessary using throttle body cleaner.