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FTP emissions were measured on a 2009MY, 4 cylinder 2.4L Malibu PZEV vehicle with 3 and 33 ppm sulfur fuel. The exhaust system employed one close-coupled and one under floor converter. FTP evaluations with Phase-II certification fuel with 33 ppm sulfur exhibited increasing NOx emissions with subsequent FTP evaluations (NOx creep). In an effort to minimize NOx creep, FTP preparation cycles and low sulfur fuels were investigated. Results indicate that utilizing the US06 cycle in between subsequent FTP's can mitigate NOx creep. FTP evaluations with 3 ppm sulfur fuel exhibited no NOx creep regardless of FTP preparation cycle and yielded overall lower NOx emissions.

Federal Test Procedure (FTP) emissions were measured on a 2009 4 cylinder 2.4L Malibu PZEV vehicle with 10 and 30ppm sulfur fuel while varying the PGM (Platinum Group Metals) of the close-coupled and underfloor converters. Base CARB PH-III certification fuel was used. Three consecutive FTPs were used to measure the impact of fuel sulfur and catalyst PGM loading combinations. In general, reducing fuel sulfur and increasing catalyst PGM loadings, decrease FTP emissions. Increasing Pd concentrations can mitigate the impact of higher fuel sulfur concentrations. The results also suggest that a 50% reduction in PGM can be achieved with a reduction in fuel sulfur from 30 to 10 ppm. On average, NMHC, CO and NOx emissions were reduced by 12, 49 and 64%, respectively with the 10 ppm sulfur fuel. In addition, HC and NOx vehicle emission variability were reduced by 74 and 57% with the 10 ppm sulfur fuel.