why does my BMW 5 Series F10/F11 (2010-2017) have poor fuel economy now

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool before starting the inspection.

2. Replace Air Filter

• Locate the air filter housing.
• Remove the screws or clips securing the air filter cover.
• Take out the old air filter and replace it with a new one, ensuring it fits snugly.
• Reassemble the air filter housing.

3. Check and Replace Spark Plugs

• Remove the ignition coil covers if equipped.
• Disconnect the electrical connectors from the ignition coils.
• Remove the ignition coils using a socket set.
• Use a spark plug socket to remove the old spark plugs.
• Inspect the spark plugs for wear and replace them with OEM specifications (typically NGK or Bosch).
• Reinstall the ignition coils and connectors.

4. Inspect Fuel System

• Connect a fuel pressure gauge to the fuel rail's test port.
• Start the engine and monitor the fuel pressure; it should match the manufacturer’s specifications (usually around 50-60 psi for BMW).
• If pressure is low, consider replacing the fuel pump or filter as needed.

5. Repair Vacuum Leaks

• Inspect all vacuum hoses and the intake manifold for cracks or disconnections.
• Replace any damaged hoses or gaskets found during the inspection.
• Use a smoke machine if necessary to identify hidden leaks.