EN
Combustion piston engine is one of the devices in which fast changeable processes occur in operationalconditions. In this paper are presented basic problems associated with research on fast changeable processes occurring in diesel engines , exemplified by the processes of indicated pressure and fuel pressure injected to engine's cylinder. Dynamical characteristics of the investigated processes were analyzed and problems of synchronous averaging of pseudo-periodical signals were considered in order to limit high frequency noise content in useful signal. Some limitations of elimination effectiveness of high frequency noisefrom tested signals have been revealed