The mixture controller is designed so that it evaluates the signal from an oxygen sensor in the exhaust pipe. It ascertains whether the actual signal value in comparison with the previous measurement has crossed a threshold in either the rich or lean direction. If it has crossed the lean threshold, the control parameter that goes to the injectors is adjusted by a large proportional step in the rich direction, and then an integration process for the parameter starts. If the rich threshold has been crossed, the integration is halted and resumed after a delay time. The cycle is repeated indefinitely, either immediately or after a short time period.
