ENGINE WITH CONTROL UNIT FOR LEAN BURN OPERATION

An internal combustion engine includes an engine block including a cylinder, a piston positioned within the cylinder and configured to reciprocate in the cylinder, an electronic throttle control system including a motor and a throttle plate, an air flow sensor configured to detect an air mass flow rate, a fuel system for supplying a controlled amount of fuel to the cylinder including a fuel injector, and an engine control unit coupled to the fuel system and the electronic throttle control system. The engine control unit is configured to determine engine speed data including a current engine speed, a previous engine speed, and a desired engine speed, control a fuel injection duration based on the engine speed data, determine air-fuel ratio data comprising a current air-fuel ratio and a desired air-fuel ratio, and control a throttle plate position based on the air-fuel ratio data.