Pulsed Secondary Air Injection: Description and Operation

This system supplies secondary air into the exhaust stream to promote rapid oxidation of exhaust emissions.
System components include a reed valve, a secondary air control valve, a check valve (except California vehicles), an electronic control unit (ECU) from the feedback carburetor system and various sensors. Non-California vehicles are equipped with an additional secondary air supply system to provide improved oxidation of contaminants.
The reed valve supplies secondary air to the front catalytic converter during engine warm-up, deceleration or heavy load conditions. It is activated by exhaust vacuum created from pulsations in the exhaust manifold. At this time extra air is then supplied to the manifold through the secondary air control valve.
The secondary air control valve is opened by intake manifold vacuum when the control valve solenoid is activated by the ECU. The ECU activates the solenoid based on information received from sensors regarding coolant temperature, engine speed, time, throttle position and idle position.