Development of Third Generation of Gasoline P-ZEV Technology

This paper describes the third generation of the partial zero emission vehicle (P-ZEV) technology originally adopted on the Nissan Sentra CA sold in California. The 2000 Nissan Sentra CA became the world's first gasoline-fueled car to qualify for P-ZEV credits from the California Air Resources Board (CARB). The third-generation P-ZEV system has been substantially reduced in size and cost, compared with the Sentra CA system, enabling it to be used on high-volume models. This system complies with the P-ZEV requirements, including those for zero evaporative emissions and Onboard Diagnostics II (OBD-II).

To achieve a more compact and lower-cost system, an ultra-thin-walled catalyst substrate, the world's first to attain a 1.8-mil wall thickness, has been adopted along with catalysts that display excellent low-temperature activity. As a result, low-temperature catalyst activity has been significantly improved. A new compact HC trap catalyst system has also been developed, which has high-efficiency HC trap catalysts arranged in two stages. Improvements were also made to the system to reduce engine-out HC and NOx emissions. These various improvements made it possible to develop a mass-produced engine system that meets the P-ZEV requirements.