240SX L4-2.4L (KA24DE) (1993)
Air Induction Valve: Description and Operation
SYSTEM PURPOSE
The Pulsed Secondary Air Injection (PAIR) System is designed to send secondary air to the exhaust manifold to promote afterburning of the exhaust
gases, reducing CO and HC. The exhaust pressure in the manifold pulsates in response to the opening and closing of the exhaust valves and decreases
periodically below atmospheric pressure creating a vacuum effect.
Pulsed Secondary Air Injection (PAIR/AIV) Input/Output Signals
CIRCUIT OPERATION
When the ECM senses the proper conditions suitable for PAIR operation, via the water temperature sensor, idle switch and crank angle sensor it
supplies the ground circuit to the PAIRC solenoid allowing the system to operate.
Fig. 6 AIV/PAIR Valve
The vacuum being transmitted to the PAIR Valve acts upon a diaphragm opening the valve port allowing the system to operate. The exhaust flow then
draws filtered air into the the manifold through the piping and PAIR Valve promoting afterburning of the unburned exhaust gasses. A set of reed valves
are mounted in the PAIR Valve to prevent exhaust gas from being sent back into the unit when the exhaust pressure exceeds atmospheric pressure.
Vacuum Control Solenoid
PULSED SECONDARY AIR INJECTION (PAIRC) CONTROL SOLENOID
The ECM supplies the ground circuit to the PAIRC solenoid. When activated, it redirects vacuum from the source and vent ports to the source and
valve ports, applying vacuum to the PAIR.