Air Injection: Description and Operation

Air Suction System Schematic:

Air Suction System Operations Chart:

The air suction (AS) system is used to direct air into the exhaust manifold to extend the combustion of unburned hydrocarbons (HC) and carbon monoxide (CO) in the exhaust system. This air is also used as the oxygen source for the catalytic converter. Air flow is controlled by a valve assembly that includes a vacuum operated shut-off valve and a reed valve. During normal operation, the shut-off valve is held open by the vacuum switching valve (VSV). The VSV is activated by the ECU with input from the coolant sensor, throttle position sensor and the air flow meter. Vacuum created by exhaust pulses opens the reed valve and air is drawn into the exhaust stream during specified conditions.