Automatic tuning of fuel injected engines

A method and apparatus for automatic tuning of fuel injected engines includes an air-fuel ratio sensor, a load device for controlling engine RPM, a digital computer and a display device. The digital computer displays a plurality of throttle positions to an operator who sets the throttle of said engine to correspond to said display of throttle position. The digital computer varies the engine RPM over the operating range of the engine to determine corresponding map values for storage in an injector signal modifier.