Air Injection System: Operation

Pulse air system uses alternating positive and negative pressure pulsations in exhaust system to draw in fresh air through air cleaner. Check valves are used to allow fresh air into exhaust, but prevent exhaust from flowing back into intake system.

Air is switched between upstream and downstream injection by 2 vacuum-operated control valves. Each control valve is switched by an electrically operated-vacuum solenoid.

Vacuum solenoids are switched on and off by MCU according to engine operating conditions. Vacuum storage tank maintains vacuum supply to switching solenoids.