A method of transient control for enrichment operation in a low-temperature combustion engine. The method includes determining if a current mode of the low-temperature combustion (LTC) engine is a positive valve overlap (PVO) mode. Determining if a previous mode of the LTC engine was also the PVO mode when the current mode is the PVO mode, wherein the previous mode is immediately prior to the current mode. Determining if the previous mode of the LTC engine was a negative valve overlap (NVO) mode when the previous mode was not the PVO mode. Initiating a predetermined enrichment PVO mode for the LTC engine based on the previous mode of the LTC engine. The predetermined enrichment PVO mode includes initiating a deep enrichment PVO mode, when the previous mode of the LTC engine was the NVO mode, and initiating a shallow enrichment PVO mode, when the previous mode of the LTC engine was not the NVO mode.

A system includes an exhaust aftertreatment system in exhaust gas receiving communication with an engine including a plurality of cylinders where the engine is structured to operate according to low load conditions and where a controller is structured to determine that at least one diesel emissions fluid (DEF) doser is frozen based on at least one of an ambient air temperature and a DEF source temperature. The controller is structured to operate the engine according to a skip-fire mode in response to a DEF flag indicating that the at least one DEF doser is frozen. The skip-fire mode comprises firing a portion of the plurality of cylinders that is less than a total amount of cylinders of the plurality of cylinders. The controller is structured to discontinue the skip-fire mode in response to determining that the at least one DEF doser is likely thawed.

Systems and methods for controlling a gasoline urea selective catalytic reductant catalyst are described. In one example, an observer is provided that corrects an estimate of an amount of NH.sub.3 that is stored in a SCR. The amount of NH.sub.3 that is stored in the SCR is a basis for generating additional NH.sub.3 or ceasing generation of NH.sub.3.

Systems and methods for estimating a temperature of an after treatment device in an exhaust system of an engine are described. In one example, the temperature is estimated during condition when an engine exits a fuel cut-out mode and excess fuel is delivered to the after treatment device for the purpose of increasing after treatment device efficiency.

An engine and one or more aftertreatment subsystems integrated into one system for optimization and control. At least one controller may be connected to the engine and the one or more aftertreatment subsystems. The controller may contain and execute a program for the optimization and control of the one system. Controller may receive information pertinent to the engine and the one or more aftertreatment subsystems for the program. The controller may prescribe setpoints and constraints for measured variables and positions of actuators according to the program to aid in effecting the optimization and control of the one system.

Systems, apparatuses, and methods for monitoring a catalyst health parameter are provided. A system includes one or more processing circuits having one or more memory devices coupled to one or more processors. The one or more memory devices store instructions that, when executed by the one or more processors, cause the one or more processors to: receive information indicative of at least one of a temperature of exhaust gas entering the aftertreatment system, a time at idle, or a mass flow of exhaust gas; determine a catalyst health management criteria based on the information; determine a catalyst health indicator based on the catalyst health management criteria being met; compare the determined catalyst health indicator to a predetermined health threshold criteria; and provide a notification based on the determined catalyst health indicator being less than the predetermined health threshold criteria.

Systems and methods for improving operation of a vehicle are presented. In one example, a controller may respond to a temperature of a catalyst to permit or temporarily inhibit a vehicle from moving. Engine load and engine emissions may be reduced by limiting vehicle motion until a catalyst temperature exceeds a threshold temperature.

A management device 100 includes: a data acquisition unit 122 configured to acquire cumulative data for each parameter related to stress acting on a DOC 33 configured to purify exhaust gas of an engine and an exhaust gas temperature of the exhaust gas raised for purification; a damage degree identification unit 123 configured to identify a degree of damage to the DOC 33 based on the acquired cumulative data; a relationship identification unit 124 configured to identify a relational expression indicating a relationship between the identified degree of damage and the exhaust gas temperature; an target information acquisition unit 125 configured to acquire an exhaust gas temperature of exhaust gas raised for purification performed by the DOC 33; and a diagnosis unit 126 configured to estimate a degree of damage to the DOC 33 based on the acquired exhaust gas temperature and the identified relational expression.

A method is provided for controlling an engine. In one example, the method may include injecting fuel to the engine; and during an operating condition, limiting injected fuel based on engine airflow to a smoke-fuel limit, the smoke-fuel limit transiently adjusted from a first smoke-fuel limit to a second smoke-fuel limit based on a duration operating at the smoke-fuel limit. In one example, the method may include during another operating condition, fuel injection not limited by the smoke-fuel limit. In some examples, the duration may be a time duration. In some examples, the duration may be a crank angle duration. In some examples, limiting the injected fuel is based on an estimated engine airflow and estimated fuel injection amount to the engine.

A temperature of a catalyst (EHC) is estimated with high accuracy. An electronic control device of the present invention controls an engine system that includes: an internal combustion engine; a motor capable of motoring the internal combustion engine; a catalyst that is installed in an exhaust passage of the internal combustion engine, has a function of being heated by energization, and purifies exhaust gas; and a downstream temperature sensor installed on the downstream side of the catalyst. The electronic control device includes: a control unit that causes the motor to motor the internal combustion engine; and an estimation unit that performs a first estimation process of estimating a temperature of the catalyst based on detection information of the downstream temperature sensor when the internal combustion engine is motored.