Volkswagen Golf MK7 (2015-2019) rough idle when cold start what's causing it

Solution

1. Preparation

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

2. Inspect and Replace Spark Plugs

• Remove the ignition coil cover using a socket set.
• Disconnect the ignition coils and pull them out.
• Remove the old spark plugs using a spark plug socket.
• Inspect the old plugs for wear or fouling.
• Install new spark plugs, ensuring to torque them to the manufacturer’s specifications (typically around 20-25 Nm).
• Reconnect the ignition coils and cover.

3. Clean or Replace the MAF Sensor

• Locate the MAF sensor in the intake duct.
• Disconnect the electrical connector and the hose clamps.
• Remove the sensor from the housing.
• Clean the MAF sensor with MAF cleaner spray or replace it if damaged.
• Reinstall the MAF sensor ensuring a snug fit and reconnect the electrical connector.

4. Inspect and Replace Fuel Filter (if applicable)

• Locate the fuel filter; it may be integrated into the fuel pump assembly.
• Relieve fuel system pressure by removing the fuel pump fuse and running the engine until it stalls.
• Disconnect fuel lines from the filter using appropriate line removal tools.
• Replace the fuel filter and reconnect the lines, ensuring all connections are secure.

5. Test and Replace Engine Coolant Temperature Sensor

• Locate the ECT sensor, usually near the thermostat housing.
• Disconnect the electrical connector and remove the sensor using a socket set.
• Install the new ECT sensor with a new O-ring or gasket, if applicable.
• Reconnect the electrical connector.