Federal and Canadian Models

Fig. 58 Air Suction System Schematic:

The air suction (AS) system is used to direct air into the exhaust ports to extend the combustion of unburned hydrocarbons (HC) and carbon monoxide (CO) in the exhaust system. This air is used as the oxygen source for the catalytic converter. Air flow is directed to the catalyst when vacuum created by exhaust pulses opens the reed valve and air is drawn into the catalytic converter.