No. 1 Anti-AFTERBURN Valve

Warm engine to normal operating temperature and ensure engine operates smoothly at idle. Stop engine. Disconnect air pump-to-air control hose at air pump. Disconnect electrical connectors from relief solenoid valve (Blue color dot) and switching solenoid valve (Gray color dot).
Start engine and run at idle. Place finger over air pump-to-air control hose. Air should not be drawn in and idle speed should not change. Disconnect vacuum hose "A" shown in Fig. 1 ; idle speed should drop. Reconnect vacuum hose "A"; speed should return to normal idle. If valve does not respond as outlined, replace No. 1 anti-afterburn valve.
NOTE: Before replacing No. 1 anti-afterburn valve, check auxiliary control unit as outlined in "Mazda Rotary Engine Auxiliary Control Device" article in this section. Also check relief solenoid valve and switching solenoid valve as described in "Mazda Rotary Engine Air Injection System" article in this section.

Fig 1: Testing No. 1 Anti-Afterburn Valve
Courtesy of MAZDA MOTORS CORP.