Abstract: A vehicle includes an internal combustion engine having a plurality of cylinders, a sensor configured to generate a sensor signal correlated with an air-fuel ratio of first and second cylinders of the plurality of cylinders, and a controller in communication with the sensor and programmed to monitor the air-fuel ratio of the first cylinder in response to an indication that air-fuel ratio measurements of the first cylinder satisfy predetermined criteria for current engine operating conditions while air-fuel ratio measurements of the second cylinder do not satisfy the predetermined criteria for the current engine operating conditions.

Abstract: A method for monitoring a secondary airflow (SAIR) system in an engine includes determining degradation of the SAIR system adding a SAIR to downstream of an engine cylinder exhaust based on a comparison of the SAIR before and after a shutdown of a SAIR pump, the SAIR calculated from a fuel injection amount, an exhaust air-fuel ratio, and an engine intake airflow. In this way, SAIR at the exhaust manifold can be monitored utilizing existing onboard sensors and technology, thereby maintaining OBD and emissions monitoring, reducing engine emissions, and maintaining costs.

Abstract: Systems and methods for operating a vehicle that may be driven to or sold in different geographical locations that may have different engine emissions and fuel economy standards are described. The systems and methods may adjust vehicle operation to comply with standards that may be enforced where the vehicle is geographically located. The standards may apply to countries, treaty zones, race track areas, off-road areas, and other geographically related standards.

Abstract: Methods and systems are provided for assessing a state of a vent hose that fluidically couples a crankcase of an engine to an engine air intake system. In one example, a method may include sealing the crankcase from the vent hose, initiating cranking of the engine, monitoring a series of pressure pulsations during a monitoring window duration via a pressure sensor positioned between a crankcase oil separator and the vent hose, and indicating a presence of degradation associated with the vent hose based on the series of pressure pulsations and the monitoring window duration. In this way, diagnosis of a state of the vent hose may be reliably assessed without crankcase pressures confounding pressure measurements as recorded via the pressure sensor.

Abstract: Methods and systems are provided for assessing a state of a vent hose that fluidically couples a crankcase of an engine to an engine air intake system. In one example, a method may include sealing the crankcase from the vent hose, initiating cranking of the engine, monitoring a series of pressure pulsations during a monitoring window duration via a pressure sensor positioned between a crankcase oil separator and the vent hose, and indicating a presence of degradation associated with the vent hose based on the series of pressure pulsations and the monitoring window duration. In this way, diagnosis of a state of the vent hose may be reliably assessed without crankcase pressures confounding pressure measurements as recorded via the pressure sensor.

Abstract: Systems and methods for operating a vehicle that may be driven to or sold in different geographical locations that may have different engine emissions and fuel economy standards are described. The systems and methods may adjust vehicle operation to comply with standards that may be enforced where the vehicle is geographically located. The standards may apply to countries, treaty zones, race track areas, off-road areas, and other geographically related standards.

Abstract: Methods and systems are provided for identifying degraded exhaust gas temperature (EGT) sensor responses. In one example, a method may include cycling an engine between a higher temperature operating mode and a lower temperature operating mode while maintaining engine torque output across the higher temperature operating mode and the lower temperature operating modes, both the higher temperature operating mode and the lower temperature operating mode providing stoichiometric exhaust gas to a downstream catalyst, and characterizing a response behavior of an EGT sensor based on output of the EGT sensor during the cycling. In this way, stepwise exhaust gas temperature changes are produced for characterizing the EGT sensor response without disrupting emissions and torque control.

Abstract: Systems and methods for operating a vehicle that may be driven to or sold in different geographical locations that may have different engine emissions and fuel economy standards are described. The systems and methods may adjust vehicle operation to comply with standards that may be enforced where the vehicle is geographically located. The standards may apply to countries, treaty zones, race track areas, off-road areas, and other geographically related standards.

Abstract: Methods and systems are provided for improving completion rates for engine system diagnostics for hybrid electric vehicles. In one example, a method may include in response to fueling of the engine of a hybrid electric vehicle being discontinued, establishing an air flow from an intake to an exhaust of the engine by relying on an electric motor to rotate the engine unfueled, and conducting a plurality of diagnostic monitors that rely on the air flow prior to reactivation of fueling of the engine. In this way, diagnostic monitor completion rates may be improved for hybrid electric vehicles, and fuel economy may be improved by coordinating the plurality of diagnostic monitors to be conducted during times when the engine is not fueled.

Abstract: Methods and systems are provided for cycle-to-cycle torque reductions under exhaust component temperature constraints. In one example, a method may include, responsive to a torque reduction request, introducing a lambda split between two sets of cylinders over a plurality of engine cycles while maintaining an average of stoichiometry between the two sets of cylinders, and, responsive to reaching a lambda split threshold, introducing differentially delayed ignition timing in both sets of cylinders. In this way, fast torque reduction may be provided while maintaining a globally stoichiometric air-fuel ratio, thereby decreasing vehicle emissions, and reducing heat-related degradation to exhaust components.

Abstract: Systems and methods for operating an engine and a transmission to reduce a catalyst light off time are disclosed. In one example, clutches of a transmission are operated to provide a desired load to the engine so that engine combustion stability may be improved while supplying heat to a catalyst so that the catalyst light off time may be reduced.

Abstract: A vehicle includes a first axle, second axle, driveshaft, engine, clutch, and controller. The first and second axles are coupled by the driveshaft. The engine is configured to generate torque in the first axle. The clutch is configured to disconnect an output of the second axle. The controller is programmed to, responsive to a clutch release request that would result in an increasing commanded torque to the first axle being greater than a threshold, decrease an engine torque such that a first axle torque is less than the threshold.

Abstract: A vehicle includes a first axle, second axle, driveshaft, engine, clutch, and controller. The first and second axles are coupled by the driveshaft. The engine is configured to generate torque in the first axle. The clutch is configured to disconnect an output of the second axle. The controller is programmed to, in response to release of the clutch resulting in an increasing commanded torque to the first axle being greater than a threshold, decrease an engine torque such that a first axle torque is less than the threshold.