D21 Hardbody 2WD L4-2389cc 2.4L SOHC MFI (KA24E) (1990)
Air Induction Valve Solenoid: Description and Operation
The Cold Air Induction 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.
Fig. 5 Solenoid Valve
When the ECU senses the predetermined conditions for AIV operation, it energizes the AIV solenoid, redirecting vacuum from the source port and
the vent port to the source port and the valve port.
Fig. 6 AIV/PAIR Valve
The vacuum being transmitted to the AIV acts upon a diaphragm opening the AIV port allowing the system to operate.
The exhaust flow then draws filtered air into the the manifold through the piping and AIV, promoting afterburning of the unburned exhaust gasses.
A set of reed valves are mounted in the AIV to prevent exhaust gas from being sent back into the AIV when the exhaust pressure exceeds
atmospheric pressure.
Fig. 121 AIV Operation
^Refer to the chart above for AIV system operating conditions.