Various systems and method for controlling exhaust gas recirculation (EGR) in an internal combustion engine are provided. In one embodiment, a method includes during a first operating condition, directing exhaust gas from a first cylinder group into an engine air intake stream and directing substantially no exhaust gas from a second cylinder group to the engine air intake stream. The method further includes during a second operating condition, directing exhaust gas from the second cylinder group through a turbocharger bypass into the engine air intake stream and reducing a fuel injection amount of the first cylinder group relative to a fuel injection amount of the second cylinder group.

Methods and systems are provided for controlling and coordinating control of a post-catalyst exhaust throttle and an EGR valve to expedite catalyst heating. By closing both valves during an engine cold start, an elevated exhaust backpressure and increased heat rejection at an EGR cooler can be synergistically used to warm each of an engine and an exhaust catalyst. The valves may also be controlled to vary an amount of exhaust flowing through an exhaust venturi so as to meet engine vacuum needs while providing a desired amount of engine EGR.

Various methods and systems are provided for diagnosing a condition of a component in an exhaust gas recirculation system. In one example, a method includes selectively routing exhaust from a first subset of engine cylinders to an exhaust passage via a first valve and to an intake passage via a second valve and determining a respective condition of each of the first valve and second valve based on a first exhaust pressure of the first subset of engine cylinders and a second exhaust pressure of a second subset of engine cylinders.

Embodiments of the present disclosure present a valve assembly that includes a valve body having a gas passage bore, a valving bore extending along a longitudinal axis and intersecting the gas passage bore, a first bearing surface concentric with the longitudinal axis and a radially spaced apart second bearing surface concentric with the longitudinal axis, wherein an interface of the gas passage bore and the valving bore defines a flow port radially intermediate the first bearing surface and the second bearing surface. The valve assembly further includes a shaft valve extending along the longitudinal axis and rotatably mounted in the valving bore.