Abstract: Various systems and methods are described for an engine system with an exhaust gas treatment system including a particulate filter. In one example method, accumulated hydrocarbons are removed from the exhaust gas treatment system by increasing an exhaust gas temperature to a first temperature responsive to a particulate filter regeneration request during extended cold idle operation. After a predetermined duration, the exhaust gas temperature is increased to a second, higher temperature to regenerate the particulate filter.

Abstract: Various systems and methods are described for an engine system with an exhaust gas treatment system including a particulate filter. In one example method, accumulated hydrocarbons are removed from the exhaust gas treatment system by increasing an exhaust gas temperature to a first temperature responsive to a particulate filter regeneration request during extended cold idle operation. After a predetermined duration, the exhaust gas temperature is increased to a second, higher temperature to regenerate the particulate filter.

Abstract: A variety of methods and devices for controlling the operation of the intake and exhaust valves in an internal combustion engine during skip fire operation are described. In various embodiments, an exhaust valve monitor or other suitable mechanism is used to detect exhaust valve actuation faults. When an exhaust valve actuation fault is detected for a particular cylinder, the corresponding intake valve is deactivated (or not activated) in circumstances when it would otherwise be activated in order to prevent the intake valve from opening into a cylinder that contains high pressure combustion gases. The described approach is particularly beneficial when skip fire operation is combined with cylinder deactivation so that air is not pumped through the cylinders during the skipped working cycles.

Abstract: A variety of methods and arrangements for detecting misfire in a skip fire engine control system are described. In one aspect, a window is assigned to a target firing opportunity for a target working chamber. A change in an engine parameter is measured during the window. A determination is made as to whether a firing opportunity before the target firing opportunity is a skip or a fire and/or whether a firing opportunity after the target firing opportunity is a skip or a fire. Based at least in part on this skip/fire determination, a determination is made as to whether the target working chamber has misfired. In various embodiments, if the target working chamber is identified as persistently misfiring, the firing sequence is modified so that the target working chamber is deactivated and excluded from the firing sequence. In still other embodiments, a torque model is used to detect engine-related problems.

Abstract: Methods and devices are described for performing engine diagnostics during skip fire operation of an engine while a vehicle is being driven. Knowledge of the firing sequence is used to determine appropriate times to conduct selected diagnostics and/or to help better interpret sensor inputs or diagnostic results. In one aspect, selected diagnostics are executed when a single cylinder is fired a plurality of times in isolation relative to a sensor used in the diagnosis. In another aspect, selected diagnostics are conducted while the engine is operated using a firing sequence that insures that no cylinders in a first cylinder bank are fired for a plurality of engine cycles while cylinders in a second bank are at least sometimes fired. The described tests can be conducted opportunistically, when conditions are appropriate, or specific firing sequences can be commanded to achieve the desired isolation or skipping of one or more selected cylinders.

Abstract: Various systems and methods are described for an engine system with an exhaust gas treatment system including a particulate filter. In one example method, accumulated hydrocarbons are removed from the exhaust gas treatment system by increasing an exhaust gas temperature to a first temperature responsive to a particulate filter regeneration request during extended cold idle operation. After a predetermined duration, the exhaust gas temperature is increased to a second, higher temperature to regenerate the particulate filter.