Solid carbon (C) is produced during hydrocarbon fuels combustion by the molecules heat decomposition process in a local lack of oxygen. More reactive hydrogen consumed the part of oxygen in the zone of an oxygen-rich mixture, so carbon particles are not gaining access to oxygen. Solid carbon particles are bound to other various materials such as mechanical impurities, sulphates, condensates, and liquid fuel residues, some of them with high toxicity – such as polycyclic aromatic hydrocarbons (PAH). The cause of high solid carbon emissions is a significant inhomogeneity of the mixture up to the value λ = 0 inside the fuel droplets where oxygen absences up to λ = ∞ in the space where fuel does not even come. Therefore, solid carbon emissions highly depend on the quality of atomization of the fuel which is injected into the cylinder. The supply of oxygen required for oxidation is improved by increasing the total amount of the air in the cylinder. In Slovakia as well as in other countries (the Czech Republic, etc.), there have been recently multiple instances of removing catalysts from vehicles by services, deactivation of diesel particulate filters (DPF, SCR), or vehicle control units reprogramming (tuning), or a combination of the previous actions. From the perspective of a company and its interest, it is a large interference with vehicle design, and it also affects the relationship with the environment. From the perspective of society, it is irrelevant whether it is the individual's conduct or the conduct of certain groups. This article explores the possible solutions for checking the illegal diesel engines conversion due to deactivation of particulate matter filters in exhaust systems of diesel engines as well as the current legislation that covers this issue.

This paper focuses on the implementation of a new exhaust-emission measurement system of motor vehicles equipped with a petrol engine and an advanced emission system. Our study deals with new methods of emission inspections using on-board diagnostics in order to increase the efficiency of emission inspection itself. The aim of implementing the new method of emission measurement is to eliminate vehicles that contribute to air pollution with emissions, due to an insufficient technical condition of the petrol engine fuel supply system.