Abstract: A method for starting an engine is provided. The method comprises in response to an engine start request, cycling a gaseous fuel injector prior to activating a starter motor. In this way, delayed engine starts using gaseous fuel may be mitigated.

Abstract: A method for starting an engine is provided. The method comprises in response to an engine start request, cycling a gaseous fuel injector prior to activating a starter motor. In this way, delayed engine starts using gaseous fuel may be mitigated.

Abstract: A method for starting an engine is provided. The method comprises in response to an engine start request, cycling a gaseous fuel injector prior to activating a starter motor. In this way, delayed engine starts using gaseous fuel may be mitigated.

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 for starting an engine is provided. The method comprises opening a throttle valve controlling air flow into an intake manifold in response to a gaseous pressure differential across a gaseous fuel injector exceeding a threshold pressure. In this way, delayed engine starts using gaseous fuel may be mitigated.

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 for starting an engine is provided. The method comprises in response to an engine start request, cycling a gaseous fuel injector prior to activating a starter motor. In this way, delayed engine starts using gaseous fuel may be mitigated.

Abstract: A method for starting an engine is provided. The method comprises opening a throttle valve controlling air flow into an intake manifold in response to a gaseous pressure differential across a gaseous fuel injector exceeding a threshold pressure. In this way, delayed engine starts using gaseous fuel may be mitigated.

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.