Air Injection: Description and Operation

AIR System:

SYSTEM DESCRIPTION

This system is used to reduce Carbon Monoxide (CO) and Hydrocarbon emissions. This system under certain conditions, adds air to the exhaust manifold to continue combustion after the exhaust gas leaves the combustion chamber. It also heats up the catalytic converter quickly on engine start-up so conversion of exhaust gases will start quickly.

The A.I.R. system includes:

^ An Air Pump:
A belt driven pump on the front of the engine and supplies the air to the system. Intake air passes through a centrifugal filter fan at the front of the pump, where foreign materials are separated from the air by centrifugal force.
^ A Control Valve:
Air flows from the pump through an ECM controlled valve (called a EAC valve) through check valves to either the exhaust ports or the converter.
^ 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.
^ Necessary plumbing.

EAC Valve:

CONTROL VALVE DESCRIPTION

EAC VALVE

The EAC valve directs the air from the air pump to the engine exhaust manifold port or to the air cleaner.

When the engine is started with a coolant temperature above 15~C, the ECM energizes the solenoid on the AIR CONTROL VALVE which directs air to the exhaust manifold. At higher speeds, air can be diverted to the air cleaner even if the solenoid is energized. It can do this by means of the pressure relief valve. Air can also be directed to the air cleaner if the following conditions exist;

1. If the engine coolant temperature is too low.
2. If the throttle is open for power enrichment for more than a short time.
3. If the system is in closed loop.

Some applications will switch air to the exhaust ports for a short period of time when entering the power enrichment mode. Also note:

1. Some applications will switch air to the air cleaner at idle.
2. Some applications have air directed to the exhaust manifold ports during idle.