Air Injection: Description and Operation

Fig. 71 Secondary air supply system.:

This system, Fig. 71, uses vacuum pulses in the exhaust manifold to draw air from the air cleaner to the exhaust manifold to promote oxidation of hydrocarbons. The control unit actuates the air suction control solenoid valve which applies manifold vacuum to the air suction cut-off diaphragm valve, opening the secondary air passage. When vacuum, created by exhaust pulses, opens the air suction reed valve, fresh air pours into the exhaust manifold. The air chambers act as silencers to reduce exhaust noise and the delay valve maintains the proper air/fuel ratio mixture after shifting gears or during deceleration.