Abstract: An engine control system is provided which calculates an optimum air/fuel ratio by minimizing the smoke produced by the engine while at the same time maximizing the engine response time for all altitudes over which the engine operates. The control system includes a microprocessor, an ambient pressure sensor, fuel injectors, and storage means. A manual adjustment is provided that allows an operator to manually adjust the air/fuel ratio within certain pre-defined limits of the optimum value.

Abstract: An apparatus is provided for operating an internal combustion engine having an inlet air filter and a plurality of solenoid operated fuel injection units adapted to receive fuel injection signals and responsively inject fuel into associated engine cylinders. The apparatus includes a sensor adapted to sense a level of clogging of the air filter and responsively produce a clogging level signal. An electronic controller is adapted to produce the fuel injection signals as a function of sensed operating parameters and in accordance with a preselected horsepower curve. The controller is further adapted to receive the clogging level signal, compare the clogging level signal to a preselected threshold and limit the maximum engine horsepower in response to the clogging level signal being equal to or greater than the preselected threshold.