Systems are provided for EGR mass and air mass estimation during steady state and transient operations. By utilizing a combination sensor comprising of a manifold absolute pressure sensing element and a differential pressure sensing element sharing a common pressure chamber with connections to the intake manifold, errors in EGR mass estimation may be reduced.

In an EGR device configured to reflux part of exhaust gas of the engine as EGR gas into intake air of the engine, an EGR valve configured to restrict a flow rate of the EGR gas is closed when rotation speed N of the engine is between a low-speed threshold and a high-speed threshold, and fuel injection rate is between a low-injection rate threshold and a high-injection rate threshold that are set for each rotation speed.

Various systems and methods are provided for controlling the temperature of outlet gasses from a throttle bypass turbine. In one embodiment, a method of operating a throttle bypass turbine comprises controlling a temperature of outlet gas flowing out of the turbine by routing the outlet gas through an exhaust gas recirculation heat exchanger positioned in an exhaust gas recirculation passage, the turbine coupled to an intake passage.

An engine assembly comprises an exhaust gas recirculation circuit, an aftertreatment apparatus and a controller. The controller is configured to determine a desired proportion of exhaust gas to be directed to the exhaust gas recirculation circuit. The controller is further configured to determine, based on the proportion of exhaust gas to be directed to the exhaust gas recirculation circuit, a baseline value for an extent to which to open the exhaust gas recirculation valve for a clean aftertreatment apparatus. The controller is further configured to determine a compensation function based on an inferred aftertreatment flow restriction value. The controller is further configured to control the extent to which the exhaust gas recirculation valve is open based on the baseline value modified by the compensation function in order to maintain the desired proportion of exhaust gas to be directed to the exhaust gas recirculation circuit.