Fast Transforms for Rapid Isolation of Misfiring Cylinders

This paper presents a method for the isolation of misfiring cylinders in an internal combustion engine.

The method is based on the measurement of the extrema of engine angular velocity. It has been shown that a number of indices can be derived from such a measurement, to provide an indication of engine performance degradation. In this study, an onboard microprocessor-based instrument samples the extrema of the engine velocity waveform in real time, generating an N or 2N vector representing each engine cycle, where N is the number of cylinders.

The data is processed by matrix transformations which are designed to isolate specific faults and their intensity. The transforms are constructed in such a way as to yield a nonzero output only when a certain fault is encountered.

The system is capable of detecting individual or multiple cylinder misfires, both complete and partial. Experimental verification has been carried out in a passenger vehicle.