A method for operating an internal combustion engine of a drivetrain of a vehicle during launching. The vehicle has an exhaust-gas aftertreatment system for purifying exhaust gas of the engine. After a starting operation of the engine, the drivetrain is operated in a first operating state. In this first operating state, the engine is operated at idle, the exhaust-gas aftertreatment system is heated by the internal combustion engine, and a launch prohibition is active. The launch prohibition that is active in the first operating state prevents launching using the internal combustion engine. After a predefined state of the exhaust-gas aftertreatment system has been attained, the drivetrain is operated in a second operating state. The launch prohibition is inactive in the second operating state, such that launching using the engine is possible in the second operating state.

A method for preheating a catalytic converter which is arranged in the exhaust-gas flow of a motor vehicle and which has an electrically heated catalyst is described. The catalytic converter is preheated with the electrically heated catalyst to a maximum temperature within a period of time before the initial engine starting operation. In the process, the temperature of the electrically heated catalyst and the battery state of the vehicle are monitored. During the preheating, it is checked whether or not the battery state has fallen below a state threshold. If so, the heating of the electrically heated catalyst is stopped, and engine-internal measures are implemented. If not, further heating of the electrically heated catalyst is implemented until the maximum temperature is reached again.

A hybrid vehicle includes a multi-cylinder engine, an exhaust gas control apparatus including a catalyst for removing exhaust gas from the multi-cylinder engine, an electric motor, and a control device configured to execute catalyst temperature increase control for stopping fuel supply to at least one cylinder and making an air-fuel ratio in each of remaining cylinders rich in a case where a temperature increase of a catalyst is requested during a load operation of the multi-cylinder engine, execute control such that an electric motor supplements insufficient drive power due to the execution of the catalyst temperature increase control, and change the air-fuel ratio in at least one of the remaining cylinders to a lean side after a temperature of the exhaust gas control apparatus becomes equal to or higher than a determination threshold value during the execution of the catalyst temperature increase control.

A system and method for a variable displacement internal combustion engine using different types of pneumatic cylinder springs on skipped working cycles to control engine and aftertreatment system temperatures are described. The system and method may be used to rapidly heat up the aftertreatment system(s) and/or an engine block of the engine following a cold start by using one or more different types of pneumatic cylinder springs during skipped firing opportunities. By rapidly heating the aftertreatment system(s) and/or engine block, noxious emissions such as hydrocarbons, carbon monoxide, NO.sub.x and/or particulates, following cold starts are significantly reduced.

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.

Disclosed is a method for use in a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream, where the process comprises the reduction of nitrogen oxides of the exhaust gas stream through the use of a reducing agent derived from an additive. The disclosed method comprises: defining an integrand to be the difference between the rate of injection of the additive and the rate of evaporation of the additive to the reducing agent multiplied by a coefficient (s), wherein the value of the coefficient (s) is between zero and one; producing an integral controller output proportional to the integral of the integrand with time; requesting a countermeasure based on the integral controller output to counteract solid deposits derived from the additive.

Systems and methods for operating an engine that includes an exhaust tuning valve in its exhaust system are described. In one example, a position of the exhaust tuning valve may be adjusted to reduce a possibility of the exhaust tuning valve becoming stuck due to freezing water. In particular, the exhaust tuning valve may be cycled as ambient temperature approaches a temperature at which water freezes.

Methods and systems are provided to heat a catalyst of an after-treatment system for a vehicle. The after-treatment system is powered by a battery. An operational parameter of the battery and the driving mode of the vehicle is determined. After receiving an indication that a first operational parameter threshold has been surpassed and a torque demand of the vehicle has been predicted, heat is provided to the catalyst of the after-treatment system based on the predicted torque demand of the vehicle surpassing a second operational parameter threshold.

A control module for an aftertreatment system that includes a selective catalytic reduction (SCR) catalyst and an oxidation catalyst, comprises a controller configured to be operatively coupled to the aftertreatment system. The controller is configured to determine an actual SCR catalytic conversion efficiency of the SCR catalyst. The controller determines an estimated SCR catalytic conversion efficiency based on a test sulfur concentration selected by the controller. In response to the estimated SCR catalytic conversion efficiency being within a predefined range, the controller sets the test sulfur concentration as a determined sulfur concentration in a fuel provided to the engine. The controller generates a sulfur concentration signal indicating the determined sulfur.

A method for determining a reference value of a presence of at least one substance (NO.sub.x) occurring in an exhaust gas stream of an internal combustion engine (101), wherein the at least one substance is subjected to exhaust treatment, the exhaust treatment being carried out in dependence on the reference value (Em.sub.ref; Em.sub.ref,1; Em.sub.ref,2) When the internal combustion engine (101) is started: accumulating the occurrence (Em.sub.ACC,1; Em.sub.ACC,2) of the at least one substance (NO.sub.x) downstream from the exhaust treatment during a first period, and determining whether to redetermine the reference value (Em.sub.ref; Em.sub.ref,1; Em.sub.ref,2) based on the accumulated occurrence (Em.sub.ACC,1; Em.sub.ACC,2) of the at least one substance (NO.sub.x).