A method for operating an engine during a fuel cut-off mode is disclosed. The method may adjust exhaust valve opening timing and exhaust valve lift of one or more cylinders to heat air flowing through the one or more cylinders so that a temperature of an after treatment device may be maintained or increased.

A heating system includes at least one electric heater disposed within the fluid flow system. A control device includes a microprocessor and is configured to determine a temperature of the at least one electric heater based on a model and at least one input from the fluid flow system. The control device is configured to provide power to the at least one electric heater based on the temperature of the at least one electric heater.

A method for cold start pre-warming of a pressure-charged internal combustion engine and/or of an exhaust gas aftertreatment device of a internal combustion engine, includes arranging a cold-starting aid in the intake duct for warming the charge air while the engine is stationary. The internal combustion engine has at least one working cylinder with at least one inlet valve and at least one outlet valve and further includes a device for setting a valve position. The internal combustion engine can be pressure-charged by a pressure-charging device operable by an electric motor. In the method, after detection of a cold start of the internal combustion engine: the cold-starting aid is activated while the engine is stationary; electric-motor operation of the pressure-charging device is activated; and a valve overlap between at least one inlet valve and at least one outlet valve is set.

A control apparatus for an internal combustion engine for adjusting an amount of air passing through a catalyst during fuel cut-off operation of the internal combustion engine, the temperature of the catalyst is caused to rise, when the fuel cut-off operation of the internal combustion engine is carried out in a state where the temperature of the catalyst is low. The apparatus is constructed such that in cases where the fuel cut-off operation is carried out in a state where the temperature of the catalyst is relatively low but equal to or higher than an activation temperature thereof, the amount of air passing through the catalyst is made larger in a period of time in which the catalyst becomes a rich atmosphere immediately after the start of the fuel cut-off operation, in comparison with a subsequent period of time in which the catalyst becomes a lean atmosphere.

Methods and systems are provided for controlling hybrid vehicle engine operation, where the vehicle engine comprises one or more cylinders dedicated to recirculating exhaust to an intake manifold. In one example, during an engine cold-start event or other event where temperature of one or more exhaust catalysts are below a temperature needed for catalytic activity, fuel injection to the dedicated exhaust gas recirculation cylinder(s) is maintained shut off, while its intake and exhaust valves are maintained activated, thus enabling the dedicated exhaust gas recirculation cylinder(s) to route air to the intake manifold of the engine, resulting in exhaust gas lean of stoichiometry that may serve to heat the catalyst. In this way, during cold start events and other events where temperature of one or more exhaust catalysts are below a temperature for catalytic activity, combustion stability issues may be avoided, and exhaust catalyst(s) rapidly heated, thereby reducing undesired tailpipe emissions.

An object is to supply fresh air and EGR gas into a cylinder in good balance according to the required load in a naturally aspirated gasoline engine. When the operation state of the engine falls in a low load range, a control apparatus adjusts the degree of opening of the second throttle while keeping the first throttle fully open and controls EGR gas quantity by adjusting the degree of opening of the EGR valve. When the operation state falls in a middle load range, the apparatus controls EGR gas quantity by adjusting the degree of opening of the first throttle while keeping the EGR valve fully open. When the operation state falls in a high load range, the apparatus adjusts the degree of opening of the first throttle while keeping the second throttle fully open and controls EGR gas quantity by adjusting the degree of opening of the EGR valve.

In a hybrid vehicle, in a case where a temperature of a catalyst is equal to or larger than a prescribed temperature that is a temperature at which purification of an exhaust gas in the catalyst begins, and charging of a storage battery is not restricted, at least one of an engine load, an engine speed, and a retard angle amount of an ignition timing is made to gradually increase, and in a case where the temperature of the catalyst is equal to or larger than the prescribed temperature and the charging of the storage battery is restricted, the engine load is fixed and at least one of the engine speed and the retard angle amount of the ignition timing is made to gradually increase.

Methods and systems are provided for reducing emissions during an engine cold start. In one example, a method may include, during emission control device heating, initiating combustion in a cylinder via a spark plug directly coupled to the cylinder and providing secondary air via a turbulent jet ignition system. In this way, an amount of hydrocarbons in feedgas provided to the emission control device prior to the emission control device reaching its light-off temperature may be reduced.

A gaseous fuel engine system includes an exhaust controller coupled with a temperature sensor and a NOx sensor, and structured to actuate open an electrically actuated bypass valve to bypass an oxidation catalyst with exhaust, based on an exhaust temperature and an exhaust NOx amount to mitigate production of yellow smoke. Yellow smoke mitigation logic may run during startup and when the gaseous fuel engine is in a lower part of an engine load range. The yellow smoke mitigation logic can be selectively triggered in response to transient engine load increases when the gaseous fuel engine is operating in an upper part of an engine load range.

Embodiments for controlling exhaust gas turbines are provided. In one embodiment, a method for controlling a turbocharger arrangement of an internal combustion engine, the turbocharger arrangement having at least a first exhaust-gas turbine and a second exhaust-gas turbine arranged downstream of the first, and an exhaust-gas aftertreatment system being arranged downstream of the second exhaust-gas turbine comprises, in a warm-up mode, controlling at least one exhaust-gas turbine so as to increase an inlet temperature of an exhaust-gas flow at the inlet into the exhaust-gas aftertreatment system. In this way, the exhaust-gas aftertreatment system may be rapidly heated.