Air Injection: Description and Operation

This system is used to direct air into the exhaust ports or catalytic converter to extend the combustion of unburned hydrocarbons (HC) and carbon monoxide (CO) in exhaust system. This air is also used as the oxygen source for the catalytic converter.




3A-C, 3E, 4A-C & 4A-LC ENGINES, EXC. CALIFORNIA

Air is drawn into the exhaust stream through an air cleaner mounted, reed type Air Suction Valve (ASV) as long as vacuum is present in the catalytic converter. Air is ducted directly to the converter to provide additional oxygen for catalyst operation. When exhaust pressure builds up in the converter, the ASV reed valve closes.




3A-C, 4A-C & 4A-LC ENGINES, CALIFORNIA

Air is drawn into the exhaust stream through a vacuum operated shut-off valve and a reed type Air Suction Valve (ASV). At idle, ported vacuum is applied to the shut off valve, the valve is open, and air is drawn into the exhaust manifold by exhaust vacuum pulsations. In this mode, the reed valve prevents exhaust pressure from forcing exhaust gasses into the air cleaner. When the throttle plate is moved, uncovering the air suction control port, the shut-off valve closes and no air is drawn into the exhaust stream. A Vacuum Transmitting Valve (VTV) is used to delay closing of the shut-off valve.