Air Injection: Description and Operation

Fig. 4 Secondary air injection system:

DESCRIPTION
The secondary air injection system, Fig. 4, reduces carbon monoxide and hydrocarbon emissions by providing air for continuing combustion of unburned gases after leaving the engine. The system utilizes natural pulses of the exhaust system and catalyst through reed valves. Fresh air mixing with the exhaust gases oxidizes the hydrocarbons and carbon monoxide and turns them into CO2 and water vapor.