AVF Engine Noises: Troubleshooting Guide (Solution)

Knocking sounds at idle, injector pump, part number: AVF.

Cause.
The knocking sounds are caused by pulsations in the vacuum line between the solenoid valve and the exhaust gas recirculation (EGR) valve. The diaphragm of the EGR valve vibrates in the same rhythm as the vacuum pulsations.

Solution:
Replace the three-part vacuum line between the solenoid valve and the exhaust gas recirculation valve (consisting of a fabric hose, a pipe, and an elbow) with a single fabric hose of the same diameter, part number N 020 282.1.