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Methods and systems are provided for improving control of high dilution EGR. An intake plenum is divided so that fresh intake air and EGR can be delivered to engine cylinders via dedicated plenum portions. Distinct sets of throttles are provided in the cylinder intake ports coupled the different ple

Methods and systems are provided for improving control of high dilution EGR. An intake plenum is divided so that fresh intake air and EGR can be delivered to engine cylinders via dedicated plenum portions. Distinct sets of throttles are provided in the cylinder intake ports coupled the different plenum portions so that a ratio of intake air flow and EGR flow to the engine cylinders can be rapidly adjusted in response to sudden changes (e.g., increase or decrease) in EGR demand.

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1. A method for an engine, comprising: delivering at least intake air into engine cylinders via a first section of a divided intake plenum;delivering at least EGR into the engine cylinders via a second, different, section of the divided intake plenum, wherein the first and second sections of the div

1. A method for an engine, comprising: delivering at least intake air into engine cylinders via a first section of a divided intake plenum;delivering at least EGR into the engine cylinders via a second, different, section of the divided intake plenum, wherein the first and second sections of the divided intake plenum are separated by a divider inside the divided intake plenum, the divider spanning an entire length of the divided intake plenum from upstream of an EGR passage to intake ports of the cylinders; andadjusting relative flow from the first section to the cylinders via a first set of throttle valves and from the second section to the cylinders via a second set of throttle valves, the first and second sets of throttle valves arranged in a perpendicular arrangement on a common shaft, the common shaft configured perpendicular to a plane of the divider. 2. The method of claim 1, wherein the first and second sets of throttle valves between the plenum and the cylinders are positioned in the intake ports of the cylinders, wherein the divider is perpendicular to a ground plane in the intake ports and parallel to the ground plane in a remainder of the plenum. 3. The method of claim 2, wherein the first set of throttle valves includes, for each engine cylinder, a first throttle valve coupled to the first section, and wherein the first set of throttle valves includes a second throttle valve coupled to the second section, and wherein each first throttle valve of the first set of throttle valves and each second throttle valve of the second set of throttle valves is actuated by a common actuator. 4. The method of claim 3, wherein the adjusting relative flow includes actuating the common actuator to open each first throttle valve of the first set of throttle valves while closing each second throttle valve of the second set of throttle valves, or close each first throttle valve of the first set of throttle valves while opening each second throttle valve of the second set of throttle valves. 5. The method of claim 4, wherein the actuating includes actuating the common shaft via the common actuator to open the first set of throttle valves by an amount while closing the second set of throttle valves by said amount. 6. The method of claim 2, wherein the intake plenum has an inlet at an upstream end for drawing in fresh intake air, the inlet upstream of a location where the EGR passage is coupled to the intake plenum, and an outlet coupled to the intake port of the cylinders at a downstream end, and wherein the divider spans the intake plenum from the inlet to the outlet, the divider dividing the plenum into upper and lower portions from the inlet to the outlet. 7. The method of claim 6, wherein the first section is one of the upper and lower portions and wherein the second section is a remaining one of the upper and lower portions. 8. The method of claim 4, wherein the adjusting is responsive to a change in EGR demand, the change in EGR demand including one of an increase in EGR demand and a decrease in EGR demand. 9. The method of claim 8, wherein the increase in EGR demand is responsive to an operator pedal tip-in to less than wide open throttle, and wherein the decrease in EGR demand is responsive to one of an operator pedal tip-in to wide open throttle and an operator pedal tip-out. 10. The method of claim 9, wherein the second section is coupled to an outlet of the EGR passage while the first section is not coupled to the outlet of the EGR passage, and wherein the EGR passage includes an EGR valve for adjusting an amount of exhaust residuals recirculated from an engine exhaust manifold into the second section of the intake plenum. 11. The method of claim 10, wherein the adjusting includes: in response to a smaller increase in EGR demand, maintaining positions of each of the first and the second set of throttle valves;in response to a larger increase in EGR demand, fully closing the first set of throttle valves while fully opening the second set of throttle valves;in response to a larger decrease in EGR demand, fully opening the first set of throttle valves while fully closing the second set of throttle valves; andin response to a smaller decrease in EGR demand, partially opening the first set of throttle valves while partially closing the second set of throttle valves, each of the partially opening and the partially closing based on the smaller decrease in EGR demand. 12. The method of claim 11, further comprising: adjusting a position of the EGR valve based on the change in EGR demand and the adjusting the relative flow from each of the first section and the second section of the divided intake plenum. 13. The method of claim 12, further comprising: in response to the smaller decrease in EGR demand, after EGR flow is at a desired EGR flow, fully closing the partially open first set of throttle valves while fully opening the partially closed second set of throttle valves. 14. A method for an engine, comprising: drawing only fresh intake air into a first portion of a plenum via a first inlet located downstream of an intake throttle and upstream of an EGR passage and distributing the fresh intake air to a plurality of outlet ports coupled to distinct engine cylinders;drawing exhaust gas into a second portion of the plenum via a second inlet located downstream of the intake throttle and upstream of the EGR passage and distributing the exhaust gas to the plurality of outlet ports, the first and second plenum portions divided from one another along an entire length of the plenum from the inlets to the outlet ports via a divider inside the plenum; andthrottling flow at the plurality of outlet ports via a first set of throttle valves coupled to the first portion and a second set of throttle valves coupled to the second portion to vary a ratio of exhaust to fresh air in the cylinders, the first and second sets of throttle valves aligned perpendicular to each other on a common shaft, and wherein the common shaft is arranged perpendicular to a plane of the divider. 15. The method of claim 14, wherein the throttling flow includes: actuating the common shaft via a common actuator to increase an opening of the second set of throttle valves while decreasing an opening of the first set of throttle valves to increase the ratio of exhaust to fresh air in the cylinders while maintaining a position of an EGR valve; andactuating the common shaft via the common actuator to decrease an opening of the second set of throttle valves while increasing an opening of the first set of throttle valves to decrease the ratio of exhaust to fresh air in the cylinders while closing the EGR valve. 16. An engine system, comprising: a divided engine intake plenum leading to intake ports of distinct engine cylinders, the divided intake plenum including: a divider dividing an entire length on an inside of the intake plenum into a first, upper and a second, lower plenum portion, wherein the divider is perpendicular to a ground plane in the intake ports and parallel to the ground plane in a remainder of the intake plenum;the first, upper plenum portion having a first inlet for drawing fresh air and a plurality of outlets coupled to the distinct engine cylinders for delivering the fresh air to the engine cylinders; andthe second, lower plenum portion having a second inlet for drawing fresh air, a third inlet positioned downstream of the second inlet for drawing exhaust gas from an EGR passage; and a plurality of outlets coupled to the distinct engine cylinders for delivering a mixture of the fresh air and the exhaust gas to the engine cylinders;a first set of throttle valves configured on a common actuatable shaft and coupled to the plurality of outlets of the first plenum portion, wherein the common shaft is arranged perpendicular to a plane of the divider;a second set of throttle valves configured on the common actuatable shaft and oriented perpendicular to the first set of throttle valves, the second set of throttle valves coupled to the plurality of outlets of the second plenum portion;an EGR valve coupled in the EGR passage, upstream of the third inlet, for adjusting an amount of exhaust residuals delivered to the second plenum portion; anda controller having non-transitory memory with computer readable instructions for: in response to an increase in EGR demand, opening the EGR valve; andadjusting a position of the common actuatable shaft to fully open the second set of throttle valves and increase throttled flow to the engine cylinders via the second plenum portion while concurrently fully closing the first set of throttle valves to decrease throttled flow into the engine cylinders via the first plenum portion. 17. The system of claim 16, wherein the controller includes further instructions for: in response to a larger decrease in EGR demand, closing the EGR valve; andadjusting a position of the common actuatable shaft to fully open the first set of throttle valves and increase throttled flow to the engine cylinders via the first plenum portion while fully closing the second set of throttle valves to decrease throttled flow into the engine cylinders via the second plenum portion. 18. The system of claim 17, wherein the controller includes further instructions for: in response to a smaller decrease in EGR demand, adjusting a position of the common actuatable shaft to increase an opening of the first set of throttle valves while decreasing an opening of the second set of throttle valves;then reducing an opening of the EGR valve; andwhen a desired EGR flow rate is reached, maintaining the opening of the EGR valve while adjusting the position of the common actuatable shaft to fully close the first set of throttle valves and fully open the second set of throttle valves.