Systems and methods for controlling exhaust gas recirculation

A system comprising:

• an engine;
• a plurality of fuel injectors operable to inject fuel into cylinders of a first cylinder group and cylinders of a second cylinder group of the engine;
• an intake passage structure coupled to the first cylinder group and the second cylinder group;
• an EGR passage structure coupled between the first cylinder group and the intake passage structure;
• an exhaust passage structure coupled to the second cylinder group;
• a controller configured to control injection of fuel to a subset of cylinders that includes less than all cylinders of the first cylinder group to obtain a target EGR rate, the control of the injection including injecting fuel to less than all cylinders of the first cylinder group, wherein the controller is further configured to control injection of fuel to at least one cylinder of the second cylinder group.

A method, comprising:

• skip firing a first cylinder group, wherein the first cylinder group provides exhaust gas through an exhaust gas recirculation (EGR) passage structure fluidly coupled between the first cylinder group and an intake passage structure;
• and
• combusting fuel in at least one cylinder of a second cylinder group, wherein the second cylinder group provides substantially no exhaust gas through the EGR passage structure, and wherein the first cylinder group is exclusive of the second cylinder group;
• wherein the step of skip firing comprises:
• in a first combustion cycle, exclusively combusting fuel in a first subset of the first cylinder group that includes less than all cylinders of the first cylinder group;
• and
• in a successive, second combustion cycle, exclusively combusting fuel in a second subset of the first cylinder group that includes less than all the cylinders of the first cylinder group, wherein the second subset is at least partially different than the first subset.