An independent periodical technical inspection (PTI)*) of vehicles is proposed in the last time as a better prevention against increased emissions of the fleet.
Several projects focused on the Diesel vehicles (HD & LD) and on the functionality of the exhaust aftertreatment systems as a key element for lowering emissions of a vehicle or machine.
The present paper summarizes the results obtained on 3 modern passenger cars Euro 6b (with EGR, DOC, DPF & SCR) during load jumps, representing the heat-up or cool-down behaviour of the exhaust system.
The portable devices for PTI were tested together with the stationary measuring systems of the engine laboratory.
In the second part of the report, the present knowledge and proposals of supplementary test procedures (like IUC or PTI) were shortly described.
It can be stated that the efficiency of the SCR-systems in a short PTI test is visible, and it is possible to quantify it in the positive or negative load jump, if a longer driving period at the constant OP (10 to 15 minutes) is realized in order to attain the stabilization of the system. For that a chassis dynamometer is recommended. A simple “5 minutes” test of the functionality of a deNOx system is not possible. On the contrary, the testing of DPF quality can be easily and quickly performed by means of a PN-measurement at vehicle standstill and it became already a legal reality in some countries.