Abstract: In internal-combustion engines with large numbers of cylinders, the rotational speed fractions of the cylinders are superimposed such that, when considering a rotational speed curve, no conclusions are possible any longer with respect to rotational speed fractions of individual cylinders. This requires new analyzing methods. According to the invention, contributions of individual cylinders of the internal-combustion engine to the rotational acceleration are determined by the rotational speed course of the crankshaft by individually cutting off the cylinders successively. From the thus obtained rotational speed course curves, a pulse response spectrum {right arrow over (I)} of an operating cycle is formed at least for the harmonic of the 0.5th order. In normal operation, the rotational speed course of the crankshaft is then continuously recorded above the angle of each operating cycle.

Abstract: A novel method and a suitable device for the cylinder-specific determination of spark failures on a reciprocating engine through a classifying unit based on measurement data that contain information about the number of crankshaft revolutions. For this process, the measurement data are subjected to a pre-processing procedure in the classifying unit and classified through a classification process, wherein within the framework of the pre-processing procedure the data are subjected to a principal axis transformation (HAT). Due to the utilization of this resource-saving method for detecting spark failures on reciprocating engines in accordance with the invention, the processing requirements for once cycle are less than 5 Kflops, despite a measurement vector v length of 240. Due to the fact that the invented device requires only a single measurement data recorder, e.g.