The paper describes the problem of the combustion process diagnostics in diesel engines of HDV vehicles in the aspect of the environment protection and misfire detection as well as its use in the OBD/EOBD systems. Vibroacoustic processes were taken into consideration and the chosenparameters ofthe vibration signals obtainedfrom the specified locations in the engine were the diagnostic estimators of the process changes. The paper discusses the diagnosis of the course of the process from the point of view of the OBD system requirements, in order to check the possibility of using the deterministic chaos method and vibroacoustic processes in on-line diagnostic processes and in the design of combustion monitors in diesel locomotive engines. This stage of the scientific studies was done to check the sensitivity of selected non-linear methods for the process changes or their lack. The paper also presents the signal analyses, limitations of the method, criteria of the process qualification and its accuracy. Diagnostic algorithms of misfire detection and possibility of its practical use in contemporary vehicle drivertrains have been described as well.