Developmet of an Idle Speed Control System for Spark-Ignition Engines

This paper discusses the design, develpoment, testing, and analysis of a stand-alone idle speed control system for general use on automotive engines. This system utilizes analog electronics and a D.C. motor actuator to adjust the throttle stop to achieve constant idle speed that rejects variations in engine torque loading. The prototype system demonstrates constant engine speed control with rejection of power steering, in-gear, airconditioning, and engine tuning variations. A mathematical model is presented that predicts these results accurately.