my BMW 3 Series E90/E91 (2005-2012) has a hard start, what could be the cause?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to ensure safety while working on electrical components.

2. Fuel System Inspection

• Tools Required: Fuel pressure gauge, screwdrivers, safety glasses, gloves.
• Sub-steps:
  1. Locate the fuel rail service port on the engine and connect the fuel pressure gauge.
  2. Turn the ignition to the "ON" position (do not start the engine) and observe the fuel pressure reading.
  3. If the pressure is below specifications, check the fuel pump and fuel filter for issues and replace if necessary.
  4. Disconnect the gauge and replace the service port cap securely.

3. Ignition System Service

• Tools Required: Socket set, torque wrench, spark plug socket.
• Sub-steps:
  1. Remove the engine cover to access the ignition coils and spark plugs.
  2. Disconnect the electrical connectors from the ignition coils and remove them using a socket.
  3. Inspect the spark plugs for wear or contamination; replace if necessary.
  4. Reinstall the ignition coils and torque them to the manufacturer’s specifications.

4. Battery and Electrical System Check

• Tools Required: Multimeter, battery terminal cleaner.
• Sub-steps:
  1. Use a multimeter to check the battery voltage; it should be above 12.6 volts.
  2. Clean the battery terminals and connections to ensure good contact.
  3. If the battery is weak, replace it with a new one and ensure proper disconnection and reconnection.