Passat L4-1984cc 2.0L DOHC (1991)
Vacuum Amplifier: Testing and Inspection
Requirements:
Engine must be at normal operating temperature, 80°C (176°F)
EGR valve must operate correctly
EGR thermo-vacuum valve must operate correctly.
Fig. 29 Vacuum Amplifier Test #1
Special tool required:
Vacuum gauge or Slack-tube tester (US 4487 or equivalent)
1.
Zero the slack-tube tester and connect it or vacuum gauge to the red line between the throttle body and the vacuum amplifier with a 'T' fitting.
2.
Start the engine and let it idle.
Reading should be 0.3 in. Hg.
Fig. 30 Vacuum Amplifier Test #2
3.
Zero the slack-tube tester and connect it or vacuum gauge to the blue line between the vacuum amplifier and the thermo-switch.
4.
Start the engine and let it idle.
Reading should be 1.9 - 3.5 in Hg.