Abstract: Feedback control of an internal combustion engine is performed based on a signal from a vibration sensor and a crankshaft angle sensor. An energy factor can be computed based on these sensor signals. A vector of energy factor can be computed as a function of crank angle degree over a particular window of engine rotation of interest. Based on the energy factor vector, combustion phasing can be estimated.

Abstract: An exhaust gas recirculation system for an internal combustion engine, which comprises an intake plenum, an exhaust gas system, and a fresh-air feed line and an exhaust gas recirculation line connected to the intake plenum, includes a sensor, arranged in the intake plenum for measuring an amount of an exhaust gas component, and a controller constructed for outputting a correcting variable based on the sensor and adjusting the percentage by mass of inert gas in the intake plenum on the basis of the correcting variable. The sensor arranged in the intake plenum is a gas concentration sensor which is equipped for determining the air ratio, the oxygen concentration or the carbon dioxide concentration in the intake plenum and to output as sensor variable a variable representing the air ratio, the oxygen concentration or the carbon dioxide concentration to controller.