Deceleration cylinder cut-off

A method of operating an engine having a crankshaft, an intake manifold and a plurality of working chambers, the method comprising, during operation of the engine:

• deactivating all of the working chambers such that none of the working chambers are fired and no air is pumped through the working chambers as the crankshaft rotates;
• subsequent to the deactivation of all of the working chambers, operating the engine in an air pumping skip fire operational mode in which some working cycles are active working cycles that are fueled and fired and some working cycles are air pumping working cycles in which air is pumped through the associated working chamber without firing to help reduce the manifold pressure relative to a manifold pressure that existed at the beginning of the air pumping skip fire operational mode;
• and
• after the manifold pressure has been reduced, operating the engine in a cylinder deactivation skip fire operational mode in which some working cycles are active working cycles that are fueled and fired and some working cycles are skipped working cycles in which the associated working chambers are deactivated such that air is not pumped through the deactivated working chambers during the skipped working cycles.

A method of operating an engine having a crankshaft, an intake manifold and a plurality of working chambers, the method comprising, during operation of the engine:

• deactivating all of the working chambers such that none of the working chambers are fired and no air is pumped through the working chambers as the crankshaft rotates;
• subsequent to the deactivation of all of the working chambers, operating the engine in an air pumping skip fire operational mode in which some working cycles are active working cycles that are fueled and fired and some working cycles are air pumping working cycles in which air is pumped through the associated working chamber without firing to help reduce the manifold pressure relative to a manifold pressure that existed at the beginning of the air pumping skip fire operational mode;
• and
• after the manifold pressure has been reduced to a target level, operating the engine in an all cylinder operational mode.

A method of operating an engine having a crankshaft, an intake manifold and a plurality of working chambers, the method comprising, during operation of the engine:

• deactivating all of the working chambers such that none of the working chambers are fired and no air is pumped through the working chambers as the crankshaft rotates;
• subsequent to the deactivation of all of the working chambers, operating the engine in an air pumping skip fire operational mode in which some working cycles are active working cycles that are fueled and fired, some working cycles are air pumping working cycles in which air is pumped through the associated working chamber without firing to help reduce the manifold pressure relative to a manifold pressure that existed at the beginning of the air pumping skip fire operational mode and some working cycles continue to remain deactivated with no firing or air being pumped through;
• and
• after the manifold pressure has been reduced, operating the engine in a cylinder deactivation skip fire operational mode in which some working cycles are active working cycles that are fueled and fired and some working cycles are skipped working cycles in which the associated working chambers are deactivated such that air is not pumped through the deactivated working chambers during the skipped working cycles.