For exhaust gas recirculation (EGR) fueling control, at least one donor cylinder of a plurality of cylinders in an engine provides exhaust gas to an air intake for the plurality of cylinders. A fuel variable restriction initially provides fuel concurrent with an intake stroke for the at least one donor cylinder in response to a transition from withholding the fuel to the plurality of cylinders.

Various methods and systems are provided for controlling air flow in a two-stage turbocharger. In one example, an engine method comprises adjusting one or more exhaust gas recirculation valves to maintain a first turbocharger within a first air flow range, and adjusting a turbocharger bypass valve to maintain a second turbocharger within a second air flow range.

A technique is provided for compensating an untrimmed oxygen (O.sub.2) sensor utilized in operation of an exhaust gas recalculation (EGR) system associated with an engine. The technique includes, in one implementation, receiving a measurement from the O.sub.2 sensor at a known pressure, where the O.sub.2 sensor is positioned on an intake side of an engine system. Humidity compensation and pressure compensation are then determined for the O.sub.2 sensor measurement, where the pressure compensation is based in part on the humidity compensation. The EGR system is controlled using the untrimmed O.sub.2 sensor measurement that has been compensated for pressure and humidity.

To provide a controller and a control method for an internal combustion engine capable of reducing the calculation error of recirculation exhaust gas amount due to changes with time of the internal combustion engines, and humidity change of intake air, and also capable of reducing the calculation error of recirculation exhaust gas amount at transient operation. The controller and the control method for the internal combustion engine calculates humidity detecting EGR rate based on intake-air humidity and manifold humidity, calculates humidity detecting opening area which realizes humidity detecting recirculation flow rate calculated based on humidity detecting EGR rate, calculates learned opening area corresponding to present opening degree of EGR valve using learning value of opening area calculated based on humidity detecting opening area, and calculates flow rate of recirculation exhaust gas for control based on learned opening area.

An internal combustion engine includes an intake air temperature adjustment apparatus that adjusts the temperature of intake air, and a control apparatus that operates at least the intake air temperature adjustment apparatus. When the internal combustion engine operates in a stoichiometric EGR mode, the control apparatus operates the intake air temperature adjustment apparatus so that the temperature of intake air entering a combustion chamber enters a first temperature region. When the internal combustion engine operates in a lean mode, the control apparatus operates the intake air temperature adjustment apparatus so that the temperature of intake air entering a combustion chamber enters a second temperature region that is a lower temperature region than the first temperature region.

Methods and systems are provided for pressure control in a boosted engine system. A variable geometry turbine (VGT) geometry, and/or wastegate (WG), and/or an exhaust gas recirculation (EGR) valve opening is adjusted based a difference between the exhaust pressure and an intake pressure, and optionally other signals (e.g., engine speed, exhaust pressure) in order to reduce the difference between exhaust and intake manifold pressures, thereby reducing pumping work losses.

The control apparatus operates an engine water temperature adjustment apparatus so that the temperature of cooling water that passes through an engine head enters a first temperature region in a lean mode, and operates the engine water temperature adjustment apparatus so that the temperature of the cooling water enters a second temperature region that is lower than the first temperature region in a stoichiometric mode. When knocking is detected after switching is started from the stoichiometric mode to the lean mode, the control apparatus performs any one of a first operation to operate a variable valve apparatus so as to retard the closing timing of an intake valve, a second operation to operate an oil jet apparatus so as to increase an oil jet amount, and a third operation to operate an EGR apparatus so as to increase an EGR amount.

Various methods and systems are provided for controlling emissions. In one example, a controller is configured to respond to a sensed exhaust oxygen concentration by changing a fuel injection timing to maintain particulate matter (PM) within a range, and then adjusting an exhaust gas recirculation (EGR) amount based on NOx sensor output and based on the change in fuel injection timing.

An engine control system of a vehicle includes a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry. The first cylinder outputs exhaust to a first three way catalyst (TWC), and the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve. An EGR control module controls opening of the EGR valve to: (i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst; and (ii) a conduit that recirculates exhaust back to an intake system of the engine.

A supercharger and a turbocharger are provided, as well as a load sensor detecting a traction load of a trailer towed by a semi-trailer and being arranged in a coupler. A combined supercharging and turbocharging is performed by the supercharger and the turbocharger when the traction load is heavier than a previously defined traction determination value. Only supercharging is performed by the turbocharger when the traction load is not more than the traction determination value.