Coasting Valve

With vacuum gauge attached in tube from air control valve to coasting valve, start engine and check that vacuum is more than 15.7 in. (400 mm) Hg. when engine speed is 800 RPM. Raise speed to about 2500 RPM and close throttle suddenly. Vacuum reading at this time should be 0-1.18 in. (0-30 mm) Hg. When engine speed decreases to 1100-1300 RPM, the reading should rise to more than 15.7 in. (400 mm) Hg.

Fig 1: Testing Coasting Valve

Courtesy of MAZDA MOTORS CORP.