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Robust on-board diagnosis of emission catalyst performance requires the development of artificially damaged "threshold" catalysts that accurately mimic the performance of damaged catalysts in customer use. The threshold catalysts are used by emissions calibrators to determine fore-aft exhaust oxygen sensor responses that indicate catalyst failure. Rather than rely on traditional trial-and-error processes to generate threshold catalysts, we have used a DFSS (Design For Six-Sigma) approach that explores, at a research level, the relationship between oxygen storage capacity (OSC) of the catalyst (i.e., the fundamental property dictating the response of the aft oxygen sensor) and key process input variables: high-temperature exposure, phosphorus poisoning, and catalyst "recovery."

Catalyzed hydrocarbon traps have shown promise in reducing cold-start tailpipe hydrocarbon emissions from gasoline powered vehicles. In this paper, we report the use of catalyzed hydrocarbon trap technology to reduce the non-methane hydrocarbon emissions from a flex-fuel vehicle that can operate on fuel mixtures ranging from pure gasoline to 85% ethanol/15% gasoline. We have found that hydrocarbon traps show a substantially greater reduction in hydrocarbon emissions when used with ethanol fuel than with gasoline. We present laboratory and vehicle test results that show that tailpipe non-methane hydrocarbon emissions from a flex-fuel vehicle can be reduced by 43% when using 85% ethanol/15% gasoline fuel and 16% when using gasoline fuel from a baseline exhaust system using a three-way catalyst. These results were obtained using a catalyzed hydrocarbon trap specifically formulated for use with ethanol fuel.