how to troubleshoot my BMW 5 Series F10/F11 (2010-2017) with a persistent misfire?

Solution

1. Preparation

• Gather tools: OBD-II scanner, spark plug socket, torque wrench, fuel pressure gauge, multimeter, compression tester, and basic hand tools.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Replace Spark Plugs

• Remove the ignition coils:
  1. Unplug the electrical connector from each ignition coil.
  2. Remove the bolts securing the coils and lift them out.
• Remove the spark plugs:
  1. Use the spark plug socket to unscrew and remove the old spark plugs.
  2. Inspect and clean any debris from the spark plug wells.
• Install new spark plugs:
  1. Check the gap on the new spark plugs using a feeler gauge and adjust if necessary.
  2. Install new spark plugs and torque them to the manufacturer's specifications (typically around 23 Nm).
• Reinstall ignition coils and reconnect electrical connectors.

3. Test Ignition Coils

• Use a multimeter to check the resistance of each ignition coil:
  1. Disconnect the coil connector and measure the primary and secondary resistance.
  2. Replace any coils that are outside of the manufacturer's specifications.
• Reinstall any replaced ignition coils.

4. Inspect and Clean Fuel Injectors

• Use a fuel injector cleaner kit or have them professionally cleaned if they are clogged.
• Verify that fuel injectors are functioning properly by checking for a consistent spray pattern.

5. Perform Compression Test

• Remove all spark plugs to ensure the engine can crank freely.
• Insert the compression tester into each cylinder’s spark plug hole and crank the engine:
  1. Record the compression readings and compare them to the manufacturer's specifications.
  2. Address any low compression issues with a rebuild or replacement of affected components.