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On-Board Diagnostics for emissions-related components require the monitoring of the catalytic converter performance. Currently, the dual Exhaust Gas Oxygen (EGO) sensor method is the only proven method for monitoring the catalyst performance for hydrocarbons (HC). The premise for using the dual oxygen sensor method is that a catalyst with good oxygen storage capacity (OSC) will perform better than a catalyst with lower OSC. A statistical relationship has been developed to correlate HC performance with changes in OSC. The current algorithms are susceptible to false illumination of the Malfunction Indication Light (MIL) due to: 1. The accuracy with which the diagnostic algorithm can predict a catalyst malfunction condition, and 2. The precision with which the algorithm can consistently predict a malfunction. A new algorithm has been developed that provides a significant improvement in correlation between the EGO sensor signals and hydrocarbon emissions.

Precious metal catalysts have been proven to be the most durable for reduction of automotive exhaust emissions. Currently, three-way catalysts are composed of mainly platinum and rhodium for reduction of CO, NOx and HC. Future catalysts are projected to contain increasing amounts of Pd to reduce current pricing of automotive catalysts. Mnolithic three-way catalysts containing Pt/Rh and Pd/Rh were aged on an engine dynamometer and were subsequently evaluated using engine sweep tests at various perturbation conditions of A/F ratio, amplitude and frequency. Stoichiometric light-off tests were also performed at various perturbation conditions. In addition, these catalysts were evaluated on FTP slave vehicles having widely different control strategies resulting in a substantial range of perturbation conditions.