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An advanced diesel aftertreatment system utilizing Selective Catalytic Reduction (SCR) with urea for lean nitrogen oxides (NOx) control was tested on a 2.7L V6 Land Rover vehicle to demonstrate the capability of achieving Tier 2 Bin 5 and lower emission standards for light-duty trucks. SCR washcoat was applied to a diesel particulate filter (DPF) to perform NOx and particulate reduction simultaneously. Advanced SCR systems employed both traditional SCR catalysts and SCR-coated filters (SCRF) to improve the NOx reduction efficiency. The engine-out NOx level was adjusted by modifying the EGR (Exhaust Gas Recirculation) calibration. Cold start NOx performance was improved by SCR warm-up strategy and urea over injection. This study showed the advanced SCR system could tolerate higher NH₃ storage in the SCR catalyst, resulting in overall higher NOx conversion on the FTP-75 test cycle.

Power Split Hybrids are unique when compared to conventional powertrains from the perspective that the engine speed is directly controlled by the motor/generator at all times. Therefore, traditional methods of detecting variations in fuel volatility do not apply for Power Split Hybrid based configurations. In their place, the Ratio-metric Fuel Compensation (RFC) method has been developed for Power Split Hybrid generator configurations to detect and compensate for engine hesitations within milliseconds of the first injection event. Furthermore, test results have shown that in the presence of low volatility fuel, RFC provides robust starts at the ideal lean air fuel ratio required for PZEV emissions compliance.