Systems and methods provide deceleration fuel cutoff regeneration of a gas particulate filter. A powertrain system includes an exhaust system containing the gas particulate filter, which is configured to collect particulate matter from an exhaust gas stream of the powertrain system. A temperature sensor is configured to monitor a temperature of the gas particulate filter. A loading monitor, such as a sensor and/or a model, is configured to provide a loading input of particulate loading of the gas particulate filter. At least one controller is configured to: determine, by comparing the loading input to stored values, whether the gas particulate filter requires the regeneration; effect a warmup of the gas particulate filter when the determination shows the gas particulate filter requires the regeneration; and initiate the regeneration when a value received from the temperature sensor meets a minimum threshold level.

Methods and systems are provided for a turbocharger. In one example, a method may include bypassing exhaust gases flowing to the turbocharger in response to a catalyst temperature being less than a threshold temperature. The bypassing includes opening a bypass valve and adjusting a position of one or more turbine nozzle vanes.

A skip fire engine controller and method of control is described wherein during transitions from a first firing density to a second firing density, a firing density and a pumping density are separately set so as to balance the conflicting demands of (a) torque control, (b) Noise, Vibration and Harshness (NVH), (c) air flow through the engine and (d) air-fuel ratio.

System and methods are described for optimizing exhaust flow rate and temperature during specified operational periods warm-up and keep-warm conditions, by minimizing or maximizing heat flux during those specified operational periods.

Various methods and arrangements for improving fuel economy and noise, vibration, and harshness (NVH) in a skip fire controlled engine are described. An engine controller dynamically selects a gas spring type for a skipped firing opportunity. Determination of the skip/fire pattern and gas spring type may be made on a firing opportunity by firing opportunity basis.

Methods and systems are provided for operating a cylinder of an engine including a pre-chamber ignition system during a cold start condition. In one example, a method may include performing a post-injection in the cylinder, and then performing a pre-chamber combustion during an exhaust stroke of the cylinder. In this way, a temperature of a catalyst of the engine may be increased, which may decrease vehicle emissions during the cold start condition.

Methods and systems for operating an engine that includes a catalyst and a particulate filter are described. In one example, release of reductant from an injector may be determined according to a plurality of metrics so that reliability of a release indication may be improved. In addition, operation of an engine may be adjusted responsive to the release indication so that exhaust system temperatures may be maintained.

A control system for a hybrid vehicle configured to prevent a reduction in the purifying performance of the catalyst in a predetermined operating mode. An operating mode of the hybrid vehicle can be selected from a first hybrid vehicle mode, a second hybrid vehicle mode, and a fixed mode. A controller that is configured to restrict a shifting operation between the first hybrid vehicle mode and the second hybrid vehicle mode via the fixed mode, when the purifying device is being warmed or the purifying device has to be warmed.

According to various embodiments, an exhaust treatment system includes a catalyst that is in direct contact with an exhaust stream, at least one sensor that senses a system parameter and produces one or more signals corresponding to the system parameter, and a controller that is configured to receive the one or more signals and control catalyst performance based on the one or more signals by regenerating the catalyst. Regenerating the catalyst includes increasing a temperature of the exhaust stream flowing to the catalyst and directing a reductant injector to adjust a flow rate of reductant being injected into the exhaust stream flowing to the catalyst.

Operating an internal combustion engine (110) having at least two combustion chambers (1-6) and at least one exhaust-gas catalytic converter (130). In one example, a beginning of the load operation phase of the internal combustion engine (110) that adjoins a coasting phase is detected. A combustion chamber of the at least two combustion chambers (1-6) is determined as the first combustion chamber; and one of other the combustion chambers is selected as the purging combustion chamber. An exhaust gas of the purging combustion chamber is directed into the same exhaust-gas catalytic converter (130) as an exhaust gas of the first combustion chamber. A first fuel quantity is fed into the purging combustion chamber such that the first fuel quantity, prior to igniting the fuel in the purging combustion chamber, is discharged to be partially or fully non-combusted in the direction of the exhaust-gas catalytic convertor (130).