Abstract: Systems and methods for operating a compressor and a compressor recirculation valve of a turbocharged engine to avoid the possibility of compressor surge are presented. The systems and methods position the compressor recirculation valve responsive to a compressor surge line that is based on two other compressor surge lines that may be a function of compressor pressure ratio and compressor flow.

Abstract: Methods and systems are provided for controlling exhaust emissions by adjusting an injection profile for different fuels injected into an engine cylinder from different fuel injectors during engine start and crank. By splitting fuel injection during start and cranking so that fuel of lower alcohol content is port injected and fuel of higher alcohol content is direct injected as one or multiple injections, the soot load of the engine can be reduced and fuel economy can be improved.

Abstract: Systems and methods for reactivating cylinders of an engine that have been temporarily deactivated to conserve fuel are presented. The systems and methods adjust fuel injection quantity and timing of direct fuel injectors to reduce particulate emissions that may form in cylinders that are being reactivated due to reduced piston and combustion chamber temperatures that may occur in newly reactivated cylinders.

Abstract: Methods and systems are provided for maintaining stoichiometry of an exhaust gas during operation of a fuel injector at a threshold pulse width. In response to operation of a fuel injector at the threshold pulse width and a rich exhaust gas air-fuel ratio, airflow is increased to the intake manifold. Engine actuators may also be adjusted to maintain torque during the increased airflow while operating the fuel injectors at the threshold pulse width.

Abstract: Methods and systems are provided for controlling exhaust emissions by adjusting an injection profile for different fuels injected into an engine cylinder from different fuel injectors during engine start and crank. By splitting fuel injection during start and cranking so that fuel of lower alcohol content is port injected and fuel of higher alcohol content is direct injected as one or multiple injections, the soot load of the engine can be reduced and fuel economy can be improved.

Abstract: Methods and systems are provided for improving engine exhaust emissions while enabling exhaust catalyst regeneration following an engine lean event. Prior to a VDE event, or prior to an engine idle-stop, ammonia is produced and stored on an exhaust underbody SCR catalyst. Then, during the engine restart after the VDE mode or the idle-stop, the stored ammonia is used to treat exhaust NOx species while an upstream exhaust underbody three-way catalyst is regenerated.

Abstract: Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected idling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during an idle adaptation relative to a zero point learned during a DFSO adaptation.

Abstract: A method for operating an engine of a vehicle. During a warm-up period following a cold start of the vehicle, a cylinder of the engine is charged to a reduced air-charge pressure, and fuel is injected into the cylinder. After the warm-up period, the cylinder is charged to a non-reduced air-charge pressure, greater for an equivalent driver demand than the reduced air-charge pressure, and fuel is injected into the cylinder.

Abstract: Various methods for compensating a deflected linkage in a wastegate arrangement are provided. In one example, current is applied to an actuator to move a wastegate valve coupled through a linkage to the actuator for diverting gasses from a turbocharger. The position of the actuator is indicated, and a correction to said indicated actuator position is applied compensating for deflection of the linkage based at least on said applied current. Said applied current is adjusted when said corrected actuator position reaches a position corresponding to a desired valve position.

Abstract: Methods and systems are provided for estimating an impact of PCV hydrocarbons on an output of an intake oxygen sensor. In one example, a method may include disabling EGR flow when the impact of PCV hydrocarbons on the output of the intake oxygen sensor is above a threshold. The impact of the PCV hydrocarbons on the output of the intake oxygen sensor may be based on a difference between the output of the intake oxygen sensor and a DPOV sensor when EGR is flow and a difference between the output of the intake oxygen sensor and expected blow-by when EGR is not flowing.

Abstract: Methods and systems are provided for reducing EGR estimation errors during lean engine operating conditions. During lean engine operation, EGR is disabled if the estimated exhaust air-fuel ratio becomes leaner than a lean threshold. The lean threshold is adjusted based on an upper limit of EGR errors that may be tolerated by the engine at a given engine speed and load.

Abstract: Methods and systems are described for controlling fuel injection in an engine equipped with a dual injector system including a port injector and a direct injector. A ratio of port injected fuel to direct injected fuel is adjusted based at least on intake valve temperature. The proportion of fuel port injected into a cylinder is increased as the intake valve temperature for the given cylinder increases to improve fuel vaporization in the intake port.

Abstract: Methods and systems are provided for flowing crankcase gases through an aspirator arranged in a PCV line. The aspirator regulates PCV flow, and may also generate vacuum depending on a position of a pintle extendable across a horizontal passage of the aspirator. When regulating PCV flow and not generating vacuum, the aspirator is fully closed and crankcase gases in the horizontal passage are metered through an orifice in the pintle. When generating vacuum, the aspirator is at least partially opened and PCV flow through the horizontal passage generates vacuum at a vacuum port of the aspirator.

Abstract: A method, comprising: operating an engine cylinder with fuel from a first injector and not a second injector and activating the second injector in response to a rail pressure increase of a fuel rail, the fuel rail coupled to the second injector. In this way, degradation of the second injector may be reduced by activating the second injector and allowing fuel flow through the second injector to reduce the pressure and temperature of the fuel rail.

Abstract: Methods and systems are provided for reducing EGR estimation errors during lean engine operating conditions. During lean engine operation, EGR is disabled if the estimated exhaust air-fuel ratio becomes leaner than a lean threshold. The lean threshold is adjusted based on an upper limit of EGR errors that may be tolerated by the engine at a given engine speed and load.

Abstract: Various systems and methods are described for an exhaust gas recirculation (EGR) system coupled to an engine in a vehicle. One example method comprises, controlling an amount of EGR according to a minimum of a first EGR amount corresponding to a temperature of a first location and a second EGR amount corresponding to a condensate formation of a second location.

Abstract: Methods and systems are provided for reducing EGR estimation errors during lean engine operating conditions. During lean engine operation, EGR is disabled if the estimated exhaust air-fuel ratio becomes leaner than a lean threshold. The lean threshold is adjusted based on an upper limit of EGR errors that may be tolerated by the engine at a given engine speed and load.

Abstract: A vacuum source arbitration system is disclosed. In one example, vacuum is supplied to a vacuum reservoir via an ejector during a first condition, and vacuum is supplied to the vacuum reservoir via an engine intake manifold during a second condition. The approach may provide a desired level of vacuum in a reservoir while reducing engine fuel consumption.

Abstract: Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor during selected idling conditions. The learned zero point is used to infer EGR flow and accordingly adjust EGR valve control. In addition, EGR valve leakage is diagnosed based on the zero point learned during an idle adaptation relative to a zero point learned during a DFSO adaptation.

Abstract: A method, comprising: operating an engine cylinder with fuel from a first injector and not a second injector and activating the second injector in response to a rail pressure increase of a fuel rail, the fuel rail coupled to the second injector. In this way, degradation of the second injector may be reduced by activating the second injector and allowing fuel flow through the second injector to reduce the pressure and temperature of the fuel rail.