how to diagnose a misfire in my BMW 5 Series G30/G31 (2017-2024)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is turned off and cool.
• Disconnect the negative battery terminal to avoid electrical issues.

2. Inspect and Replace Spark Plugs

• Remove the engine cover if necessary using a socket set.
• Disconnect the ignition coils and remove them using a socket wrench.
• Unscrew and extract the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear and replace them with OEM or equivalent parts. Torque new spark plugs to the manufacturer’s specification (typically 18 ft-lbs for BMW).
• Reinstall the ignition coils and reconnect all electrical connectors.

3. Check and Replace Ignition Coils

• If faulty ignition coils are identified, replace them.
• Remove the defective ignition coil by pulling it out from the spark plug.
• Install the new ignition coil and ensure it is seated correctly.
• Reconnect electrical connectors and secure any retaining clips.

4. Fuel System Inspection and Repair

• Attach a fuel pressure gauge to the fuel rail test port and turn the ignition to ON (without starting the engine) to check for fuel pressure.
• If pressure is below specifications (typically around 50-60 psi), inspect the fuel pump and filter. Replace them if necessary.
• For clogged injectors, you may clean them using a professional cleaning kit or replace them if cleaning doesn’t resolve the issue.

5. Address Vacuum Leaks

• Inspect all vacuum hoses for cracks or disconnections.
• If any leaks are found, replace the affected hoses.
• Use smoke testing if necessary to locate hard-to-find leaks.