Air Injection: Description and Operation

AIR System:

Purpose:
The AIR management system is used on 5.7L (C/K) 10 series with standard transmission and California Emissions to reduce Carbon Monoxide (CO) and Hydrocarbon (HC) emissions. This system under certain conditions, adds air (oxygen) to the exhaust manifold to continue oxidation after the exhaust gas leaves the combustion chamber. The heat from this reaction brings the catalytic converter up to operating temperature faster when the engine is cold.

Operation:
This system consists of an AIR pump, an electric AIR control valve with solenoid, check valve(s), and necessary plumbing.

AIR Pump:
A belt driven AIR pump supplies air through a centrifugal filter fan to the secondary AIR injection bypass valve. The shape of the centrifugal filter fan and the direction of fan rotation prevents foreign material from entering the pump with incoming air.

Air Cleaner:
The air cleaner acts as a silencer for diverted air.

Check Valves:
The check valve, on the AIR injection pipe, prevent back flow of exhaust gases into the AIR pump.

EAC Valve:

AIR Bypass Valve:
When the engine is started with a coolant temperature above 15°C (45°F), the ECM energizes the solenoid on the AIR Control Valve which directs air to the exhaust manifold.

1. At higher speeds, air can be redirected to the air cleaner by the pressure relief valve even though the solenoid is energized.

2. Air can also be directed to the air cleaner if the following conditions exist:

- Low manifold pressure (overrun).
- Quick vacuum rise (rapid deceleration).
- Rich engine condition.

3. The solenoid can be de-energized and air is directed to the air cleaner, under the following conditions:

- If the engine coolant temperature is too low.
- If the throttle is opened to power enrichment for more than a short time.
- If the system is in "Closed Loop" mode.
- If the MIL (Service Engine Soon) lamp is ON.

4. Some applications will switch air to the ports for a short time when entering power enrichment.

- Some applications have a "Closed Loop" idle with air directed to the air cleaner.