Abstract: A vehicle includes first and second electric machines constrained to rotate in unison and configured to power a common axle. A controller is programmed to, in response to activation of the vehicle, select one of the first and second speed sensors as a representative speed sensor, and, in response to the electric machines being in speed control, command speeds to the first and second electric machines based on a difference between a target speed of the electric machines and a measured speed of the representative speed sensor.

Abstract: A vehicle includes first and second electric machines constrained to rotate in unison and configured to power a common axle. A controller is programmed to, in response to activation of the vehicle, select one of the first and second speed sensors as a representative speed sensor, and, in reponse to the electric machines being in speed control, command speeds to the first and second electric machines based on a difference between a target speed of the electric machines and a measured speed of the representative speed sensor.

Abstract: Methods and systems are provided for detecting throttle obstructions in a vehicle. In one example, after engine start up, throttle icing condition resulting from the throttle capturing ice fragments originally formed within a charge air cooler or an intake passage upstream of throttle, may be detected. Responsive to detecting the throttle icing condition, the throttle may be adjusted to a fully open position independent of accelerator pedal position, and maintained at the fully open position for a threshold duration while maintaining a desired torque, to release the captured ice fragments from the throttle.

Abstract: Methods and systems are provided for detecting throttle obstructions in a vehicle. In one example, after engine start up, throttle icing condition resulting from the throttle capturing ice fragments originally formed within a charge air cooler or an intake passage upstream of throttle, may be detected. Responsive to detecting the throttle icing condition, the throttle may be adjusted to a fully open position independent of accelerator pedal position, and maintained at the fully open position for a threshold duration while maintaining a desired torque, to release the captured ice fragments from the throttle.

Abstract: Methods and systems are provided for improving boost response in a turbocharged engine. In one example, a method may include in response to a tip-out following a tip-in, when an exhaust catalyst temperature is within a threshold range, deactivating fuel injectors to the engine and increasing air flow to an exhaust turbine based on a desired increase in a turbine speed to maintain the turbine speed at or above a threshold speed.

Abstract: Methods are provided for reducing transient fuel issues in a multi-fuel engine system. When transitioning from co-fueling with a first fuel split ratio to co-fueling with an alternate fuel split ratio, the change in fuel split ratio is gradually ramped in over multiple engine cycles. This reduces combustion stability issues and the disturbance potential of a wholesale fuel change.

Abstract: Methods and systems are provided for improving boost response in a turbocharged engine. In one example, a method may include in response to a tip-out following a tip-in, when an exhaust catalyst temperature is within a threshold range, deactivating fuel injectors to the engine and increasing air flow to an exhaust turbine based on a desired increase in a turbine speed to maintain the turbine speed at or above a threshold speed.

Abstract: A method is described for adjusting the amount of gaseous fuel injected based on the sonic choked flow rate through a restriction. Because the sonic choke flow rate continues to decrease as tank pressure decreases, the method includes computing the sonic choke flow rate through the restriction based on system variables and enforcing the rate of CNG injection to be less than the sonic choke flow rate through the restriction. Thereby, the mass flow rate to the fuel injector can be substantially maximized to substantially minimize the time for fuel tank emptying, particularly during the last amount of tank emptying when the contents of the gaseous storage tank is low.

Abstract: Methods and systems are provided for reducing exhaust temperatures during high engine load conditions in engine systems configured to operate with multiple fuels. Stoichiometric cylinder operation is provided via injection of a gaseous fuel such as CNG. In response to elevated exhaust temperatures, the cylinder is enriched by injecting a liquid fuel, such as gasoline, while maintaining the injection of CNG and while maintaining spark timing at MBT.

Abstract: Methods are provided for reducing transient fuel issues in a multi-fuel engine system. When transitioning from co-fueling with a first fuel split ratio to co-fueling with an alternate fuel split ratio, the change in fuel split ratio is gradually ramped in over multiple engine cycles. This reduces combustion stability issues and the disturbance potential of a wholesale fuel change.

Abstract: A method is described for adjusting the amount of gaseous fuel injected based on the sonic choked flow rate through a restriction. Because the sonic choke flow rate continues to decrease as tank pressure decreases, the method includes computing the sonic choke flow rate through the restriction based on system variables and enforcing the rate of CNG injection to be less than the sonic choke flow rate through the restriction. Thereby, the mass flow rate to the fuel injector can be substantially maximized to substantially minimize the time for fuel tank emptying, particularly during the last amount of tank emptying when the contents of the gaseous storage tank is low.

Abstract: Methods and systems are provided for adjusting a transmission shift schedule in engine systems configured to operate with multiple fuels. During low engine speed and high engine load conditions, when an air charge temperature is elevated, engine operation is shifted from gasoline usage to CNG usage. The torque advantage of CNG usage is leveraged to advance a transmission upshift schedule and delay a downshift schedule to improve vehicle responsiveness when operating with CNG only.

Abstract: Methods and systems are provided for reducing exhaust temperatures during high engine load conditions in engine systems configured to operate with multiple fuels. Stoichiometric cylinder operation is provided via injection of a gaseous fuel such as CNG. In response to elevated exhaust temperatures, the cylinder is enriched by injecting a liquid fuel, such as gasoline, while maintaining the injection of CNG and while maintaining spark timing at MBT.