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Dual fuel injection systems, like PFI+DI (port fuel injection + direct injection system) are being increasingly used in gasoline engine applications to increase the engine performance, fuel efficiency and reduce emissions. At a given engine operating condition, the air/fuel error is a function of the fraction of fuel injected by each of the fuel systems. If the fraction of fuel from each of the fuel system is changed at a given operating condition, the fuel system error will change as well making it challenging to learn the fuel system errors. This paper aims at describing the adaptive fueling control algorithm to estimate the fuel error contribution from each individual fuel system. Considering the fuel injection system slope errors to be the significant cause for air-fuel errors, a model structure was developed to calculate the fuel system adaptive correction factor as a function of changing fraction of fueling between the fuel systems.

Lean NOx Traps are used to treat the NOx emissions from lean-burn engines by storing the NOx under lean conditions and reducing the NOx during periodic rich excursions. However, sulfur poisons the adsorption sites of the traps. The sulfur can be removed from the NOx trap by operating rich at high temperatures for several minutes. This results in the release of some SO2 but also large quantities of H2S, which is a source of customer dissatisfaction that must be reduced or eliminated. This paper describes the use of a nickel-containing catalyst and air/fuel control to maximize the release of SO2 and minimize the emissions of H2S during the desulfation of a lean NOx trap. We present laboratory and vehicle data with a nickel-containing catalyst located downstream of a lean NOx trap during desulfations of the trap. The nickel effectively reduced the emissions of H2S during the desulfation while improving the robustness to fluctuations in the air/fuel control.