Air Injection: Description and Operation

Air Injection Schematic:

Purpose:
The Air Injection Reaction (AIR) system helps reduce Hydrocarbons (HC), Carbon Monoxide (CO) and Oxides of Nitrogen (NOx) exhaust emissions.

The AIR system heats the catalytic converter quickly on engine start up so conversion of exhaust gases can occur sooner.

A single bed, three-way catalyst, monolith converter is used for each cylinder bank. It consists of a three-way catalyst which controls all three emissions.

Air Injection System:

Operation:

Electric Air Pump
The electric air pump supplies air to the AIR system. Intake air passes through an inlet silencer at the front of the pump. The air is then pressured and pumped to the control valve. The air pump is controlled by the ECM and is protected by a 25 amp fuse.

Check Valves
The check valves prevent back flow of exhaust gases into the pump in the event of an exhaust backfire.

Electronic Switching Valve:

Control Valve
A control valve directs flow from the electric air pump to the exhaust ports or away from the exhaust ports. Air from the electric air pump enters the body of the control valve and builds pressure against the Electric Switching Valve (ESV).


ESV Solenoid
An electric solenoid controls the air flow through the ESV. The ESV solenoid is normally closed and controls vacuum to an internal valve which performs a switching operation by directing air flow from the electric air pump to the exhaust ports (solenoid energized) or away from the exhaust ports (solenoid de-energized). The ESV is controlled by the ECM.