Intake Manifold Vacuum Test: Notes

Bring the engine to normal operating temperature. Connect vacuum tester to the intake manifold. Run the engine at the specified idle speed.

The vacuum gauge should read between 51--74 kPa (15--22 in-Hg) depending upon the engine condition and the altitude at which the test is performed. Subtract 3.37 kPa (1 in-Hg) from the specified reading for every 304.8 m (1, 000 feet) of elevation above sea level. The reading should be steady. If necessary, adjust the gauge damper control (where used) if the needle is fluttering rapidly. Adjust damper until needle moves easily without excessive flutter.