how to fix BMW 3 Series F30/F31 (2012-2019) engine misfire code P0300?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before beginning work.

2. Inspect and Replace Spark Plugs

• Tools Required: Spark plug socket, torque wrench, dielectric grease.
• Remove the engine cover if necessary.
• Using the spark plug socket, carefully remove each spark plug.
• Inspect the spark plugs for wear; replace any that are damaged or excessively worn.
• Apply a small amount of dielectric grease to the threads of the new spark plugs.
• Install new spark plugs with a torque specification of 18 Nm (13 lb-ft).
• Reinstall the engine cover.

3. Check and Replace Ignition Coils

• Tools Required: Ratchet and socket set.
• Remove the ignition coil covers if present.
• Disconnect the electrical connectors from each ignition coil.
• Remove the bolts securing the ignition coils and carefully extract them from the cylinder head.
• Inspect the coil connectors and replace if damaged.
• Install new ignition coils, ensuring they are seated properly.
• Reconnect the electrical connectors and replace the coil covers.

4. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit (if required), ratchet and socket set.
• Locate the fuel injectors and disconnect the electrical connectors.
• Remove the fuel rail bolts and gently lift the fuel rail away from the engine.
• Carefully extract the fuel injectors from the rail.
• Clean the injectors using a cleaning kit or replace them if clogged or damaged.
• Reinstall the injectors, ensuring proper seating, and reattach the fuel rail.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine (optional) or carburetor cleaner.
• Inspect all vacuum hoses and the intake manifold for cracks or disconnections.
• If using a smoke machine, introduce smoke to identify leaks.
• If using carburetor cleaner, spray around suspected areas and listen for RPM changes.

6. Verify Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition to the "On" position without starting the engine to check for proper pressure according to manufacturer specifications (typically between 50-60 psi).
• If the pressure is low, investigate the fuel pump or fuel filter for potential issues.