Air Injection: Description and Operation

Fig. 12 Air Injection System:

To help lower the amount of CO and HC emitted during engine warm-up, additional air is introduced into the exhaust manifolds to assist in the oxidation process.
The air is delivered by an engine powered air pump, Fig. 12. The air pump is of the rotary vane, positive displacement type and is driven by a crankshaft driven belt. The air pump is controlled by an electrically operated clutch that disengages when the engine coolant temperature has exceeded 95°F (35°C) or when the engine speed exceeds 2500 RPM.
To prevent hot exhaust gases from damaging the air pump a check valve and a vacuum operated switching valve are located in the air delivery line.
The operating vacuum to the switching valve is controlled by a solenoid operated valve. The solenoid operated valve is operated at the same time as the air pump clutch.