how to fix my Volkswagen Passat B8 (2015-2022) that has a rough idle after new spark plugs

Solution

1. Preparation

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

2. Inspect Spark Plugs

• Remove the ignition coils to access the spark plugs.
• Use a socket wrench to carefully remove each spark plug.
• Inspect each spark plug for signs of damage, improper gap, or wear.

3. Reinstall Spark Plugs

• Check and adjust the gap of each spark plug to the manufacturer's specifications (typically around 0.028-0.032 inches for this model).
• Apply a small amount of anti-seize compound to the threads of each spark plug (if recommended).
• Carefully install the spark plugs and torque them to the manufacturer's specifications (typically around 22 ft-lbs).
• Reinstall the ignition coils and ensure they are securely connected.

4. Check Electrical Connections

• Inspect the wiring harness connected to the ignition coils for any signs of wear or damage.
• Ensure all connectors are clean and seated properly.
• Use a multimeter to test the ignition coils for proper resistance and functionality.

5. Inspect Fuel Delivery

• If the rough idle persists, check the fuel pressure using a fuel pressure gauge.
• Replace the fuel filter if it shows signs of clogging or if it hasn’t been replaced per the maintenance schedule.
• Consider cleaning the fuel injectors using a fuel system cleaner.