my Volkswagen Golf MK7 (2015-2019) has a rough idle, what's causing it?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to avoid electrical shorts.
• Ensure the vehicle is on a flat surface and securely parked.

2. Inspect and Replace Spark Plugs

• Remove the engine cover (if applicable) using a socket set.
• Unscrew and remove the old spark plugs using a spark plug socket.
• Inspect the spark plugs for wear; replace them with new ones if necessary (OEM recommended).
• Torque the new spark plugs to manufacturer specifications (typically around 20 Nm).

3. Clean or Replace the Idle Air Control Valve (IAC)

• Locate the IAC valve on the throttle body.
• Disconnect the electrical connector and remove any mounting screws.
• Clean the IAC valve using throttle body cleaner or replace it if it's defective.
• Reinstall the IAC valve and reconnect the electrical connector.

4. Inspect and Repair Vacuum Leaks

• Check all vacuum hoses for cracks or leaks.
• Replace any damaged hoses with new ones.
• Ensure all connections are tight and secure.

5. Test Fuel System

• Use a fuel pressure gauge to measure fuel pressure at the fuel rail.
• If the pressure is low, check the fuel filter and replace it if clogged.
• Test the fuel pump operation; replace if it fails to maintain adequate pressure.