Air Injection: Description and Operation

SYSTEM DESCRIPTION
The Air Injection Reaction (AIR, or secondary air injection) system is used to reduce Carbon Monoxide (CO) and Hydrocarbon (HC) emissions. The system supplies fresh air to the exhaust system to promote continued combustion of unburned hydrocarbons and carbon monoxide. This also helps heat up the catalytic converter more quickly on engine start-up so the catalytic reactions can begin sooner.

The A.I.R. system includes:

Air Pump And Valve Assembly Installation:

ELECTRIC AIR PUMP
A computer controlled electric air pump provides air for the system during open loop operation only, for a maximum time of 80 seconds.

Electric Pulse-Air Shut-Off Valve:

ELECTRIC DIVERTER VALVE (OR ELECTRIC PULSE-AIR SHUT OFF VALVE)
The EDV directs the flow of air from the electric air pump to the exhaust ports or to the atmosphere.

CONTROL (EDV) SOLENOID
The Electric Divert Valve Solenoid is normally closed and controls vacuum to an internal diaphragm valve which directs air flow from the electric air pump to the exhaust ports (solenoid energized) or to the atmosphere (solenoid de-energized). The electric air pump operation and EDV solenoid are controlled by the ECM. When air to the exhaust ports is desired, the ECM turns on both the electric air pump and the EDV solenoid. The ECM does this by completing the circuit to ground to energize the air pump relay and EDV solenoid.

Exhaust Check-Valve:

CHECK VALVES AND NECESSARY PLUMBING
The check valves prevent back flow of exhaust into the pump in the event of an exhaust backfire.



CAUTION: Mask off the inlet air silencer whenever pressure washing or steam cleaning the engine compartment to prevent damage to the air pump.