why does my BMW 3 Series E90/E91 (2005-2012) have a delayed start?

Solution

1. Preparation

• Gather necessary tools and parts for the repair.
• Disconnect the negative battery terminal to ensure safety.

2. Battery Inspection

• Tools Required: Multimeter
• Check the battery voltage; it should be above 12.4 volts.
• If voltage is low, recharge or replace the battery as needed.

3. Fuel System Check

• Tools Required: Fuel pressure gauge
• Locate the fuel rail and connect the fuel pressure gauge.
• Turn the ignition to the "On" position (do not start) and check fuel pressure; it should meet specifications (usually around 50-60 psi for this model).
• If pressure is low, inspect the fuel pump and fuel filter for clogs or failure.

4. Starter Motor Test

• Tools Required: Multimeter, socket set
• Remove the starter motor from the vehicle.
• Connect the multimeter to the starter terminals and check for voltage when attempting to start the engine.
• If there is voltage but the starter does not engage, replace the starter motor.

5. Ignition System Inspection

• Tools Required: Socket set, spark plug wrench
• Remove the spark plugs and inspect for wear or fouling.
• Replace any damaged or worn spark plugs.
• Check the ignition coils for proper operation; replace any faulty coils.

6. Wiring and Connectors Examination

• Visually inspect wiring and connectors related to the starting system.
• Clean any corroded connectors and repair damaged wiring as necessary.