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

Solution

1. Preparation

• Tools Needed: OBD-II scanner, socket set, torque wrench, compression tester, fuel injector cleaner.
• Disconnect the negative battery terminal to ensure safety while working on electrical components.

2. Inspect Ignition Components

1. Remove the engine cover (if applicable) using a socket set.
2. Disconnect the ignition coils from each spark plug.
3. Inspect spark plugs for wear (burnt tips, carbon buildup) and replace if necessary.
4. If coils are damaged or misfiring, replace the ignition coils with new ones.
5. Reinstall spark plugs and coils, ensuring they are torqued to the manufacturer's specifications.

3. Examine Fuel Injectors

1. Remove the fuel rail assembly to access the injectors.
2. Inspect each fuel injector for clogs or damage.
3. Clean the injectors using a fuel injector cleaner or replace them if necessary.
4. Reinstall the fuel rail and ensure all connections are secure.

4. Check for Vacuum Leaks

1. Inspect all vacuum hoses for cracks or disconnections.
2. Use a smoke machine to identify any vacuum leaks around the intake manifold and throttle body.
3. Replace any leaking hoses or gaskets as needed.

5. Test Compression

1. Remove all spark plugs to facilitate the compression test.
2. Insert the compression tester into each cylinder and crank the engine.
3. Record the compression readings and compare them against manufacturer specifications.
4. If readings are low, further investigation may be needed into piston rings or valve seals.