Air Injection: Description and Operation

PURPOSE
The Pulsed Secondary Air Injection (PAIR) system is designed to send secondary air to the exhaust manifold, utilizing the vacuum caused by exhaust pulsation in the exhaust manifold.




OPERATION
The exhaust pressure in the exhaust manifold usually pulsates in response to the opening and closing of the exhaust valve and decreases below atmospheric pressure periodically. if a secondary air intake pipe is opened to the atmosphere under vacuum conditions, secondary air can be drawn into the exhaust manifold in proportion to the vacuum.
The PAIR valve is controlled by the ECCS control module, corresponding to the engine coolant temperature. When the engine is cold, the PAIR valve control system operates to reduce HO and CO.
In extremely cold conditions, PAIR valve control system does not operate to reduce after-burning. This system also operates during deceleration for the purpose of blowing off water around the PAIR valve.