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 ECT 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

ECT VALVE

The ECT valve directs the air from the air pump to the engine exhaust manifold ports 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. Low manifold vacuum.
2. Rapid deceleration.
3. Rich engine condition.

When the solenoid on the AIR Control Valve is de-energized the air is then switched up to the air cleaner under the following conditions:

1. If the engine coolant temperature is to low.
2. If the throttle is opened for power enrichment for to long of a time.
3. If the system is in "Closed Loop" mode.
4. If the "Service Engine Soon" lamp is on.

Also note:

1. Some applications have a "Closed Loop" idle which directs air from the air pump to the air cleaner.
2. Some applications will switch air to the exhaust ports when in the power enrichment mode is entered.
3. Some applications have air directed to the exhaust ports at idle.