Abstract: An automatic control system is shown to vary the mixture of fuel-to-air in a conventional internal combustion engine to minimize resulting pollutants and maximize engine efficiency and performance. The system senses manifold vacuum and engine acceleration and based, in part, upon such inputs forces the mixture leaner until an instability event is detected at which time the system rapidly forces the mixture richer at a predetermined rate and time period to overcome the instability. The mixture is then again gradually forced leaner. The rate of leaning is controlled by the vacuum pressure so that no leaning occurs at or near full throttle and the rate of leaning is decreased either gradually or incrementally as power requirements decrease. The air-to-fuel ratio may be adjusted by regulating the introduction of secondary air or by adjusting the quantity of fuel injection. A control system for individually monitoring and correcting fuel injection rates of individual cylinders is provided.

Abstract: An automatic control system is shown to vary the mixture of fuel-to-air in a conventional internal combustion engine to minimize resulting pollutants and maximize engine efficiency and performance. The system senses manifold vacuum and engine acceleration and based, in part, upon such inputs forces the mixture leaner until an instability event is detected at which time the system rapidly forces the mixture richer at a predetermined rate and time period to overcome the instability. The mixture is then again forced leaner. The rate of leaning is controlled by the vacuum pressure so that no leaning occurs at or near full throttle and the rate of leaning is decreased as power requirements decrease Further, secondary air is introduced substantially tangentially to the primary air/fuel flow to maximize mixture between the primary and secondary flows.