why does my Volkswagen Passat B8 (2015-2022) have a rough idle after starting?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before performing any work.

2. Clean Throttle Body

• Required Tools: Throttle body cleaner, soft brush, microfiber cloth.
• Remove the air intake duct from the throttle body.
• Spray throttle body cleaner into the throttle body while holding the throttle open.
• Use a soft brush to gently scrub away carbon deposits.
• Wipe clean with a microfiber cloth and reassemble the duct.

3. Inspect and Replace Air Filter

• Required Tools: Screwdriver or socket set (if applicable to your model).
• Locate the air filter housing and remove the cover.
• Take out the old air filter and inspect it for dirt and damage.
• Insert a new air filter, ensuring it fits snugly in the housing.
• Reinstall the cover and secure it properly.

4. Check Fuel Pressure

• Required Tools: Fuel pressure gauge.
• Locate the fuel rail and connect the fuel pressure gauge to the test port.
• Turn the ignition to the "ON" position (without starting the engine) to check the fuel pressure.
• Compare the reading with the manufacturer's specifications (typically around 50-60 psi for most vehicles).
• If pressure is low, consider replacing the fuel pump or fuel filter.

5. Inspect and Replace Spark Plugs

• Required Tools: Spark plug socket, torque wrench.
• Remove the ignition coil packs to access the spark plugs.
• Use the spark plug socket to carefully unscrew and remove each spark plug.
• Inspect the plugs for wear or fouling and replace with OEM specifications.
• Torque the new plugs to the manufacturer's specification (usually around 15-20 ft-lbs) and reassemble the ignition coils.