Air Injection System: Operation
When vehicle exceeds set speed of speed sensor and manifold vacuum is above set vacuum of control switch, the control switch solenoid valve and control switch are open. The control unit energizes the air suction control solenoid valve to apply manifold vacuum to the air suction cut-off diaphragm valve, which opens the secondary air passage.
When vacuum, induced by pulsation in exhaust manifold, makes air suction reed valve open, fresh air enters exhaust manifold. The control switch bellows adjust their operation in response to atmospheric pressure. Air chambers act as silencers to reduce exhaust noise.