EGR Vacuum Modulator: Turbo

Disconnect the 2 vacuum hoses from EGR vacuum modulator. Plug port "P" on EGR vacuum modulator. See Fig 1.
Apply air pressure to port "Q" on vacuum modulator. See Fig 1. Air should flow freely through air filter side of EGR vacuum modulator.
Start engine. Increase engine to 3500 RPM. Repeat test procedures in steps 1) and 2). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations.

Fig 1: Identifying Ports & Testing EGR Vacuum Modulator (Turbo)