Method and system for providing smooth mode transitions in a variable displacement internal combustion engine

An internal combustion engine system, comprising:

• a plurality of cylinder banks, each one of the banks having at least one cylinder;
• a pair of plenums, each one of the banks being fed air through a corresponding one of the pair of manifold plenums;
• a main throttle body having an outlet for feeding air to a pair of output ports, each one of such output ports being coupled to feed the air to a corresponding one of the pair of manifold plenums;
• a main throttle plate disposed in the main throttle body for controlling airflow passing to the outlet of the main throttle body;
• a plenum throttle plate disposed in one of the pair of plenums for controlling air from the one of the pair of output ports of the main throttle body coupled thereto to cylinders in the bank of cylinders coupled thereto;
• and
• a control system for, during transitions from an engine operation mode using a first number of the cylinders to a mode using a different number of the cylinders, operating the plenum throttle plate to provide a change in airflow to said one of the pair of plenums in a first sense thereby changing the airflow in the other one of the bank of cylinders in a second, opposite sense.