Advances in digital computer technology have brought the application of on-line digital control systems to bear on the problem of exhaust gas pollution from the internal combustion engine. One application, adaptive digital control of fuel consumption based on a feedback of an analysis of exhaust gases, is explained. A small gasoline engine is modified with a fuel injection system, thus the engine, digital computer, and gas analyzer interface is developed. The engine's exhaust pollutants, based on real time operating conditions, are minimized while performance is retained.The delay time limitations experienced by the feedback transducer are demonstrated by a transient mode of operation. The relevance of this investigation and some future applications are discussed.