Abstract: A method for calculating exhaust gas temperature indirectly at points in or around an engine exhaust after treatment system for use in determining an amount of unburned hydrocarbons resident therein at a given point in time.

Abstract: A method for calculating exhaust gas temperature indirectly at points in or around an engine exhaust after treatment system for use in determining an amount of unburned hydrocarbons resident therein at a given point in time.

Abstract: A system to protect an after treatment system from the effects of hydrocarbon accumulation on a catalyst. An engine system microprocessor using software estimates the amount of hydrocarbon accumulation on the after treatment system based on engine system parameters and other parameters. The accumulated hydrocarbons can cause an exothermic event if the catalyst temperature is allowed to ramp up too quickly. Similarly, accumulated hydrocarbon can temporarily reduce after treatment system performance. In the case of SCR, the microprocessor can control a reductant injector to modulate the amount of reductant being injected into the after treatment system to control the amount of ammonia slip. Alternatively or in addition to, the microprocessor can communicate with proper electronic control modules to modulate the engine system parameters such as engine speed, fuel, and back pressure to control engine exhaust flow temperature during operation of the engine system.

Abstract: An engine control system including an engine configured to generate exhaust comprising an exhaust constituent and to operate in a first operating mode or a second operating mode different from the first operating mode. The engine control system can include a plurality of sensors configured to generate temperature data corresponding to at least one of a measured exhaust temperature and an ambient temperature, and exhaust constituent data corresponding to an exhaust constituent concentration. The engine control system can include a controller operatively coupled to the plurality of sensors and the engine, and configured to receive the temperature data and the exhaust constituent data from the plurality of sensors, and change an operating state of the engine from the first operating mode to the second operating mode when the temperature data is less than a predetermined temperature threshold and the exhaust constituent data is greater than a predetermined exhaust constituent threshold.