Air Injection: Description and Operation

SYSTEM DESCRIPTION

This system is used to reduce Carbon Monoxide (CO) and Hydrocarbon (HC) emissions. It also heats up the catalytic converter quickly, on engine start-up, so the conversion of exhaust gases will occur sooner.


The A.I.R. system includes:

1. An Air Pump:
A belt driven pump on the front of the engine supplies the air to the system. Intake air passes through a centrifugal filter fan at the front of the pump, where foreign material is separated from the air by centrifugal force.
2. A Control Valve:
Air flows from the pump through an ECM controlled valve (called a control valve) through check valves to either the exhaust ports or the silencer.
3. Check Valves:
The check valves prevent back flow of exhaust into the pump in the event of an exhaust backfire or pump drive belt failure.
4. Necessary plumbing.

Electric Air Control Valve:

ELECTRIC AIR CONTROL VALVE (EAC)

The system uses an EAC valve to combine electronic control with normal diverter valve function.
When the solenoid is energized, the valve will perform similar to a standard diverter valve. Air from the pump is directed to the exhaust ports unless there is a sudden rise in manifold vacuum due to vehicle deceleration.
When the solenoid is de-energized, the pressurized air from the air pump is allowed to enter the decel timing chamber. This places sufficient pressure on the valve diaphragm to overcome spring pressure, which allows air to divert to the atmosphere.
At high engine speeds, excess air is allowed to exhaust to atmosphere through the pressure relief valve.

Deceleration Valve:

DECELERATION VALVE

To prevent backfiring during high vacuum conditions, a deceleration (gulp) valve is used to allow air to flow into the intake manifold. This allows the air/fuel mixture, which is rich due to the high vacuum created by the throttle valve closing, to become leaner.