Air Injection: Description and Operation

Pulse Air System:

General
The Pulse Air Injection System uses the alternating exhaust pressure pulsations instead of an air pump to inject air into the exhaust system and produce exhaust gas oxidation. Air is routed from the air cleaner through hoses to air control valves which are controlled by air switch solenoids. The air switch solenoids are controlled by the Micro Computer Unit (MCU). At the appropriate signal from the MCU, the air control valve is opened and air is allowed to flow through the air injection check valve. From there the air enters the exhaust stream either at the front exhaust pipe (upstream) or at the catalytic converter (downstream) depending on which of the air injection circuits have been opened.

Check Valve:

Check Valves
The check valves are reed valves that are opened and closed by the positive and negative exhaust pressure pulsations. During the negative exhaust pulse (low pressure) atmospheric pressure opens the check valve and air is forced into the exhaust system.

Air Control Valves
The air control valves control the supply of air routed to the check valves.

Air Switch Solenoids
The air switch solenoids control the air control valves by switching the vacuum ON and OFF as directed by the MCU.

Micro Computer Unit
The MCU switches air either upstream or downstream by energizing or de-energizing the air switch solenoids. The MCU uses predetermined engine operating criteria to determine proper air management.

Vacuum Storage Tank
Vacuum is stored in a tank until released by either one of the air switch solenoids.