A number of embodiments of engine controls and engine control methods that employ instantaneous rate of combustion is the combustion chamber at a sensed parameter. Rate of combustion is determined by a linear equation based upon data arrived from combustion chamber pressures. The system is adapted to operate under different control modes so as to provide specific control for normal running, lean burn, maximum torque, cold starting, transient conditions, and/or knock control. The desired rate of combustion is achieved by engine control adjustments.