Deceleration cylinder cut-off (DCCO) methodology with enhanced EGR

A system comprising:

• an engine having an intake manifold an exhaust manifold, a crankshaft, a plurality of working cylinders each having at least one intake valve and at least one exhaust valve, and an exhaust gas recirculation conduit providing fluid communication between the intake manifold and the exhaust manifold;
• and
• a controller configured to:
• while the engine is operating, in response to a no engine torque request:
• deactivate a number of the working cylinders less than the entire plurality of working cylinders such that none of the deactivated working cylinders are fired and no air is pumped through the deactivated working cylinders as the crankshaft rotates;
• and
• operate at least one of the plurality of working cylinders that is not deactivated to pump air through the non-deactivated working cylinder;
• and
• control the flow of air pumped through the non-deactivated working cylinder to selectively flow to the intake manifold or to an exhaust aftertreatment device disposed between the exhaust manifold and a tailpipe.

A method of operating an engine having an intake manifold, an exhaust manifold, a crankshaft, four working cylinders each having at least one intake valve and at least one exhaust valve, and an exhaust gas recirculation conduit providing fluid communication between the intake manifold and the exhaust manifold, the method comprising:

• while the engine is operating, in response to a no engine torque request:
• deactivating three of the working cylinders by controlling valve lift using a sliding cam for the intake and exhaust valves associated with the deactivated cylinders such that no air is pumped through the deactivated working cylinders as the crankshaft rotates;
• operating the working cylinder that is not deactivated to pump air through the non-deactivated working cylinder;
• and
• controlling gas flow through the exhaust gas recirculation conduit to circulate air pumped through the non-deactivated working cylinder to the intake manifold.