Microprocessor Controlled Three - Way Catalyst Efficiency Monitoring System (A Progress Report)

The present paper describes the progress design of microcontrolled three-way catalyst efficiency monitoring system [1]. The system is based on a powerful microprocessor and utilizes the moving average value differential signal from a pair of thermocouples installed at the catalyst outlet and inlet sections. This signal is processed in real time using an appropriate statistical algorithm and the corresponding results are compared to experimentally determined limiting values to assess the current state of the catalyst efficiency during driving conditions. The result of this comparison is presented on a LCD display as A, B, or C catalyst condition signal. The advantages and results of this new algorithm version are presented in this paper. The system has already installed at and operates on new and used cars provided that the type of catalyst used has been experimentally tested to provide the necessary limiting values that characterize its relative levels of efficiency. It can also be reprogrammed and calibrated via a RS232C serial interface.