Abstract: Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Abstract: Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Abstract: Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Abstract: Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Abstract: Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Abstract: Methods and systems for controlling and/or diagnosing an emission control system of a vehicle having a first SCR region upstream of a second SCR region are provided herein. One exemplary method includes, indicating degradation based on a first SCR region performance during a first condition; and indicating degradation based on a second SCR region performance during a second condition, the first condition different than the second condition. In this way, different levels of degradation among different SCR regions may be used to indicate emissions levels have increased above a threshold value, for example.

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: A system and method for supplying fuel to an engine is disclosed. In one example, a first controller supplies injector commands to a second controller via an asynchronous serial communication bus. The system may reduce the complexity of supplying two or more fuels to an engine.

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.

Abstract: Embodiments for indicating degradation of a piston-cooling jet system are provided. In one example, an engine method comprises indicating degradation of a piston-cooling jet system in response to a relationship between engine speed and oil pressure at maximum oil pump displacement conditions. In this way, engine operation may be adjusted in response to an indicated degradation.

Abstract: Methods and systems for controlling and/or diagnosing an emission control system of a vehicle having a first SCR region upstream of a second SCR region are provided herein. One exemplary method includes, indicating degradation based on a first SCR region performance during a first condition; and indicating degradation based on a second SCR region performance during a second condition, the first condition different than the second condition. In this way, different levels of degradation among different SCR regions may be used to indicate emissions levels have increased above a threshold value, for example.

Abstract: Methods and systems for controlling and/or diagnosing an emission control system of a vehicle having a first SCR region upstream of a second SCR region are provided herein. One exemplary method includes, indicating degradation based on a first SCR region performance during a first condition; and indicating degradation based on a second SCR region performance during a second condition, the first condition different than the second condition. In this way, different levels of degradation among different SCR regions may be used to indicate emissions levels have increased above a threshold value, for example.

Abstract: Methods and systems for controlling an emission control system of a vehicle having a first SCR region upstream of a second SCR region are provided herein. One exemplary method includes, in a first mode: adjusting an amount of reductant injected upstream of a first SCR region based on a condition of the first SCR region. The method may also include, in a second mode: adjusting the amount of reductant injected upstream of the first SCR region based on a condition of the second SCR region.

Abstract: Embodiments for indicating degradation of a piston-cooling jet system are provided. In one example, an engine method comprises indicating degradation of a piston-cooling jet system in response to a relationship between engine speed and oil pressure at maximum oil pump displacement conditions. In this way, engine operation may be adjusted in response to an indicated degradation.

Abstract: A system and method for supplying fuel to an engine is disclosed. In one example, a first controller supplies injector commands to a second controller via an asynchronous serial communication bus. The system may reduce the complexity of supplying two or more fuels to an engine.