Abstract: A method and a system for determining if fuel containing more than the desired concentration of sulfur is being combusted in an engine. The engine includes a selected catalytic reduction (SCR) module or a lean NOx trap (LNT) and the system includes various sensors and a controller for calculating NOx conversion ratio and ammonia slip. Timers are utilized for purposes of positively identifying when sulfur in the fuel is causing a substandard performance of the exhaust system. If the timers or time periods are not satisfied, a conversion ratio failure or an ammonia slip failure is attributable to equipment failure, and not sulfur in the fuel. However, if the timers are satisfied, then sulfur in the fuel is positively identified as the problem thereby enabling the operator to eliminate equipment failure as a possible source of the conversion ratio or ammonia slip failure.

Abstract: A method of determining and regulating a mass flow rate exhaust gases recirculated into an engine is disclosed. The method may comprise directing the exhaust gases through a venturi and sensing a differential exhaust pressure across the venturi. The method may further include sensing an absolute exhaust pressure at the venturi, and sensing a temperature of the exhaust gases. The method may further include determining the mass flow rate of the exhaust based on the sensed differential fluid pressure, absolute fluid pressure, and temperature.

Abstract: A method of determining and regulating a mass flow rate exhaust gases recirculated into an engine is disclosed. The method may comprise directing the exhaust gases through a venturi and sensing a differential exhaust pressure across the venturi. The method may further include sensing an absolute exhaust pressure at the venturi, and sensing a temperature of the exhaust gases. The method may further include determining the mass flow rate of the exhaust based on the sensed differential fluid pressure, absolute fluid pressure, and temperature.