Abstract: A skip fire control system for an engine of a vehicle includes a set of sensors configured to measure a set of operating parameters of the engine corresponding to a volumetric efficiency of the engine, a set of sub-systems having a set of operational states that affect transitions between different firing patterns/fractions of the engine, and a controller configured to, based on the set of operating parameters and the set of operational states of the set of sub-systems, determine a best firing pattern/fraction by taking into account losses or penalties to transition at least some of the set of operational states of the set of sub-systems to obtain a target firing pattern/fraction, and control the engine based on the target firing pattern/fraction to maximize an efficiency of the engine.

Abstract: A skip fire control system for an engine of a vehicle includes a set of sensors configured to measure a set of operating parameters of the engine corresponding to a volumetric efficiency of the engine, a set of sub-systems having a set of operational states that affect transitions between different firing patterns/fractions of the engine, and a controller configured to, based on the set of operating parameters and the set of operational states of the set of sub-systems, determine a best firing pattern/fraction by taking into account losses or penalties to transition at least some of the set of operational states of the set of sub-systems to obtain a target firing pattern/fraction, and control the engine based on the target firing pattern/fraction to maximize an efficiency of the engine.

Abstract: 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.

Abstract: 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.

Abstract: Various methods and arrangements for improving fuel economy in decel fuel cut-off (DFCO) operation of an internal combustion engine are described. In one aspect, a catalytic converter bypass valve diverts the pumped air in DFCO mode from flowing through a catalytic converter. The diverted, pumped air may flow through a bypass line or be returned to the engine intake manifold through an exhaust gas recirculation return line. Another aspect of the invention relates to directing the diverted pumped air through an emission control device.

Abstract: Methods and arrangements for transitioning an engine between a deceleration cylinder cutoff (DCCO) state and an operational state are described. In one aspect, transitions from DCCO begin with reactivating cylinders to pump air to reduce the pressure in the intake manifold prior to firing any cylinders. In another aspect, transitions from DCCO, involve the use of an air pumping skip fire operational mode. After the manifold pressure has been reduced, the engine may transition to either a cylinder deactivation skip fire operational mode or other appropriate operational mode. In yet another aspect a method of transitioning into DCCO using a skip fire approach is described. In this aspect, the fraction of the working cycles that are fired is gradually reduced to a threshold firing fraction. All of the working chambers are then deactivated after reaching the threshold firing fraction.

Abstract: Methods and arrangements for transitioning an engine between a deceleration cylinder cutoff (DCCO) state and an operational state are described. In one aspect, transitions from DCCO begin with reactivating cylinders to pump air to reduce the pressure in the intake manifold prior to firing any cylinders. In another aspect, transitions from DCCO, involve the use of an air pumping skip fire operational mode. After the manifold pressure has been reduced, the engine may transition to either a cylinder deactivation skip fire operational mode or other appropriate operational mode. In yet another aspect a method of transitioning into DCCO using a skip fire approach is described. In this aspect, the fraction of the working cycles that are fired is gradually reduced to a threshold firing fraction. All of the working chambers are then deactivated after reaching the threshold firing fraction.