Vacuum Amplifier: Testing and Inspection

Fig. 27 Testing Vacuum Amplifier (California):

Requirements:
Engine must be at normal operating temperature, 80°C (176°F)
EGR valve must operate correctly
EGR thermo-vacuum valve must operate correctly.

1. Start the engine and let it idle.
2. If idle speed is erratic, disconnect the vacuum line from the EGR valve.
3. If the idle speed increases, replace the vacuum amplifier.
4. If the idle remains erratic, remove and plug vacuum line 'A', Fig. 27.
5. Connect a hand operated vacuum pump to the vacuum amplifier.
6. Apply 20 mm (0.79in.) Hg vacuum to the vacuum amplifier, and the idle speed should drop.
7. If the idle speed does not drop, replace the vacuum amplifier.