Abstract: Diesel Exhaust Fluid is metered into an engine exhaust gas aftertreatment system having a close coupled SCR catalyst and a main SCR catalyst. The DEF is injected into two injector locations, one upstream of the close coupled SCR catalyst and another upstream of the main SCR catalyst, the quantity of DEF in each injector being based on primarily the temperature at the main SCR catalyst and the mass flow of the NOx through the aftertreatment system. This method of injection enables a relatively better fuel economy outcome while meeting the regulated tailpipe NOx emission levels and the N2O formation limits.

Abstract: Diesel Exhaust Fluid is metered into an engine exhaust gas aftertreatment system having a close coupled SCR catalyst and a main SCR catalyst. The DEF is injected into two injector locations, one upstream of the close coupled SCR catalyst and another upstream of the main SCR catalyst, the quantity of DEF in each injector being based on primarily the temperature at the main SCR catalyst and the mass flow of the NOx through the aftertreatment system. This method of injection enables a relatively better fuel economy outcome while meeting the regulated tailpipe NOx emission levels and the N2O formation limits.

Abstract: According to at least one aspect of the present technology, a method is provided for compensating the output of a mass air flow sensor in response to humidity level. The method includes determining an actual mass air flow value (MAF_ACT) using the mass air flow sensor. The method also includes determining an actual humidity value (HUM_ACT) of the air flow that is measured by the mass air flow sensor. The method further includes determining if the actual humidity value (HUM_ACT) is outside of a preselected operating range. If the actual humidity value (HUM_ACT) is outside of the preselected operating range, the method determines a humidity-compensated mass air flow value (MAF_HUM) as a function of the actual mass air flow value (MAF_ACT) and the actual humidity value (HUM_ACT).