Abstract: The invention is directed to a control system for an internal combustion engine with reference to air throughput, rotational speed and lambda. In this control system, a decoupling device is provided between open loop and closed loop control signals which act with different speeds. An ignition signal is influenced in dependence upon a lambda-dependent signal via at least one dead time member. In this way, phases having unfavorable opposing influence on control branches of different reaction durations are reduced.

Abstract: The speed to be measured, either engine speed or vehicle (drive wheel) speed, is measured by a tachogenerator which trips a timer to provide a series of measurements. When the system is in use, a driver can store the actual speed at a selected moment as the desired speed. From a linearized model of vehicle speed or engine speed response to acceleration or deceleration of the engine by displacement of a control member, system parameters a.sub.1 and b.sub.1 are derived. The actual speed signal is multiplied by a.sub.1 and added algebraically (to produce a difference signal) to the desired speed signal, with the resulting signal then being multiplied by another constant derived from the system parameter b.sub.1 by reference to weighting factors p and q of a cost minimizing equation relating to the relative significance of obtaining a small control deviation and of limiting or increasing the amplitude of the control signal. An output signal is then provided by the second multiplying stage.