Engine Control by an On-Board Computer

A spark ignited internal combustion engine with computer controlled spark and exhaust gas recirculation has been operated over the CVS test cycle. At the 1975 emission level, a 10-20% improvement in fuel economy on the test vehicle over the initial production 1975 California vehicle was measured. Comparable driveability, octane, emission levels, and performance were obtained. The initial calibration for the control of spark and EGR was developed from engine dynamometer testing; computer simulations allowed for calibration development prior to vehicle implementation. Cost effectiveness questions have not been resolved.