what can cause my Volkswagen Passat B8 (2015-2022) to stall at stop lights?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety while working on electrical components.

2. Fuel System Inspection

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Connect the fuel pressure gauge to the test port.
  3. Turn the ignition to the "ON" position without starting the engine and check the pressure reading. It should meet manufacturer specifications (typically around 50-60 psi).
  4. If pressure is low, check the fuel pump and filter for blockage or failure.

3. Throttle Body Cleaning

• Tools Required: Throttle body cleaner, soft brush, and rags
• Sub-steps:
  1. Disconnect the intake duct from the throttle body.
  2. Remove the throttle body from the intake manifold by unscrewing the mounting bolts.
  3. Spray throttle body cleaner onto a soft brush and clean the throttle plate and interior surfaces.
  4. Reinstall the throttle body and reconnect the intake duct.

4. Idle Air Control Valve Inspection

• Tools Required: Screwdriver set and cleaning supplies
• Sub-steps:
  1. Locate the idle air control valve (IAC) on the throttle body or intake manifold.
  2. Remove the IAC valve connector and unscrew the mounting screws to take out the valve.
  3. Inspect the IAC for carbon buildup and clean it as necessary.
  4. Reinstall the IAC and reconnect the wiring harness.

5. Spark Plug and Ignition Coil Replacement

• Tools Required: Socket set, torque wrench
• Sub-steps:
  1. Remove the engine cover to access the ignition coils.
  2. Disconnect the electrical connectors from each ignition coil.
  3. Unscrew the ignition coils and remove them from the spark plugs.
  4. Remove the spark plugs using a spark plug socket.
  5. Install new spark plugs, ensuring proper torque (usually around 15 lb-ft).
  6. Reinstall the ignition coils and reconnect the electrical connectors.