A method comprises determining that an aftertreatment system is in a cold-operation mode; initiating a low engine-out NOx (LEON) mode by controlling a component of a vehicle containing the aftertreatment system to decrease an instantaneous engine out NOx (EONOx) amount and to increase exhaust energy relative to a normal operation mode for an engine of the vehicle; receiving information indicative of an operating status of the vehicle during the LEON mode; disengaging the LEON mode; subsequent to disengaging the LEON mode, initiating a thermal management (TM) mode for the aftertreatment system, wherein the TM mode is initiated by controlling a component of the vehicle to increase fueling to the engine for a power level by reducing engine efficiency and directing excess fuel to the aftertreatment system; receiving information indicative of an operating status of the vehicle during the TM mode; and disengaging the TM mode.

Controllers and methods for managing transitions into and/or out of a cylinder cut off mode are described. In some embodiments, a skip fire based transition into a cylinder cut off mode is used in which the fraction of working cycles that are fired is gradually reduced to a threshold firing fraction. Once the threshold firing fraction has been reached, all of the working chambers are deactivated.

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 heating an exhaust after treatment device and producing smooth engine torque output are described. In one example, exhaust valve opening time is adjusted to compensate for additional torque that may be generated via combusting rich air-fuel mixtures in cylinders. In addition, intake valve lift may be adjusted to compensate for additional torque that may be generated via combusting rich air-fuel mixtures in cylinders.

The disclosure provides a method and a device for closed-loop control of a temperature of a component in an exhaust-gas tract of an internal combustion engine. The exhaust-gas tract has a temperature sensor arranged upstream of the component. The method includes providing a control circuit for the closed-loop control of the temperature of the component and detecting a measurement signal by the temperature sensor during the operation of the internal combustion engine. The measurement signal is characteristic of an exhaust-gas temperature. The measurement signal is used as a measured controlled variable for the control circuit for the closed-loop control of the temperature of the component. The method also includes determining a temperature model for the exhaust-gas temperature of the exhaust gas upstream of the component. The temperature model is used as a predictor for the control circuit. Also, a modeled controlled variable is provided from the temperature model.

A variety of methods and arrangements for controlling the exhaust gas temperature of a lean burn, skip fire controlled internal combustion engine are described. In one aspect, an engine controller includes an aftertreatment system monitor and a firing timing determination unit. The aftertreatment monitor obtains data relating to a temperature of one or more aftertreatment elements, such as a catalytic converter. Based at least partly on this data, the firing timing determination unit generates a firing sequence for operating the engine in a skip fire manner such that the temperature of the aftertreatment element is controlled within its effective operating range.

A heater for use in heating a fluid flow through a passageway is provided that includes a continuous resistive heating element having a predefined shape that is directly exposed to the fluid flow. The predefined shape includes a cross-sectional geometry that provides a required heat distribution, structural strength, and reduced back pressure within the passageway. The predefined shape may include airfoils, while the cross-sectional geometry provides a required heat distribution, structural strength, and reduced back pressure within the passageway.

Methods and systems for operating an engine that includes a controller and a NOx sensor are described. In one example, output of the NOx sensor is selectively made available to software modules within the controller when an offset in NOx sensor output is not expected. If the offset in NOx sensor output is expected, the NOx sensor output may not be made available to the software modules.

An engine controller executes a fuel introduction process of introducing, in a state in which the crankshaft of an internal combustion engine is rotating, air-fuel mixture that contains fuel injected by a fuel injection valve into the exhaust passage without burning the air-fuel mixture in the cylinder. When the oxygen concentration of exit gas that has passed through a three-way catalyst decreases during the execution of the fuel introduction process, the engine controller executes a stopping process of stopping the fuel introduction process.

Methods and systems for operating an engine that includes a controller and a NOx sensor are described. In one example, output of the NOx sensor is selectively made available to software modules within the controller when an offset in NOx sensor output is not expected. If the offset in NOx sensor output is expected, the NOx sensor output may not be made available to the software modules.