Abstract
Keywords
OBD systems certification and approval, OBD monitors testing, Oxygen Sensor malfunction simulation, TWC malfunction simulation, exhaust gas system modelling
Abstract
This paper discusses the methods and features of a set of technological solutions that allow technicians who conduct certification to carry out comprehensive and thorough performance tests of OBDII and EOBD diagnostic procedures and functions responsible for continual monitoring of the oxygen sensors and assessment of the catalytic converter's effectiveness, based on measurements taken by the previously mentioned sensors.
The first part of this work discusses relevant formal and legal requirements in this area, which have begun to have a substantial bearing on the vehicle manufacturing business, as stipulated by both European and American regulations. Those requirements cover methods used in onboard diagnostic systems to detect vehicle's malfunctions or deteriorated functionality of oxygen sensors, and these will also be given consideration in this paper. These diagnostic tests are presented and then classified into several categories, (sensor circuit performance tests, functional tests, active and passive tests). Some focus is given to methods and algorithms used to assess the condition of the catalytic converter (its oxygen capacity), while examining the signal waveforms from pre- and post- catalyst oxygen sensors.
The next part of the paper describes assessments and premises connected with the developed system, and its capabilities and limitations in simulating any of the most common situations occurring during a vehicle's life cycle. Focus is given to conditions that the system must meet so that its real impact on the engine's performance could adequately match that of real problem situations it is designed to simulate. To substantiate this discussion, a practical description of hardware and software components of the project follows the theoretical discussion. This section examines the methods used and the algorithms which modify the oxygen sensor signal waves, and are dependant on the simulated technical condition of the sensors and the catalytic converter.
Finally, in its conclusion, the paper presents sample results obtained when functional characteristics of OBD diagnostic procedures were tested on real vehicles.