Air Injection: Description and Operation

Fig. 77 Secondary air supply system.:

This system, Fig.77, 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.
On 1983 models, the control switch bellows and vacuum tank adjust their operation in response to atmospheric pressure.
On all models, the air chambers act as silencers to reduce exhaust noise and the ratio mixture after shifting gears or during deceleration.
On 1983 models, the air suction control solenoid valve is actuated when any of the following conditions are met:
a. On Federal and high altitude vehicles, engine speed is below 1400 RPM and vehicle speed is above mph for manual transmission or above 15 mph for automatic transmission.
b. Engine speed is below 3150 RPM and coolant temperature is below 158 deg. F..
c. Control switch is on and vehicle speed is above mph for manual transmission or above 15 mph for automatic transmission.
d. Engine speed is below 3150 RPM and air suction vacuum switch is on.