Abstract: Systems and methods for identifying alcohol content of a fuel in an engine. In one example approach, a method comprises adjusting fuel injection to the engine based on fuel alcohol content identified from crankshaft acceleration. For example, the crankshaft acceleration may be generated by modulating an air/fuel ratio in a selected cylinder across a range of air/fuel ratios while keeping the engine at stoichiometry.

Abstract: Systems and methods for monitoring cylinder air/fuel imbalances are provided. In one example approach, a method comprises, identifying a cylinder with a potential air/fuel imbalance based on crankshaft accelerations generated by a series of rich, lean, and stoichiometric conditions in the cylinder while keeping the engine at stoichiometry.

Abstract: Systems and methods for identifying alcohol content of a fuel in an engine. In one example approach, a method comprises adjusting fuel injection to the engine based on fuel alcohol content identified from crankshaft acceleration. For example, the crankshaft acceleration may be generated by modulating an air/fuel ratio in a selected cylinder across a range of air/fuel ratios while keeping the engine at stoichiometry.

Abstract: Methods and systems are provided for monitoring a fuel vapor recovery system including a fuel tank isolation valve coupled between a fuel tank and a canister. During selected conditions, the valve is modulated and pressure pulsations in the fuel vapor recovery system are monitored. Valve degradation is identified based on correlations between the valve modulation and the resultant pressure pulsations.

Abstract: A vehicle is provided with a fuel system, a controller, and a diagnostic module with an orifice, a pressure sensor, and a pump, the module connecting the fuel system to atmosphere. The controller measures a reference pressure across the orifice to provide a threshold, isolates the fuel system, and provides a code in response to comparing a series or measured pressures to the threshold. A method for performing an evaporative leak diagnostic is provided. A valve in a diagnostic module is commanded to a vent position. A pump is operated to measure a reference pressure across an orifice to provide a threshold. A valve is commanded to a test position. The pump is operated to place the fuel system in a low pressure state, and a series of pressures in the fuel system is measured. A diagnostic code is provided after comparing the series of pressures to the threshold.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: Systems and methods for identifying alcohol content of a fuel in an engine. In one example approach, a method comprises adjusting fuel injection to the engine based on fuel alcohol content identified from crankshaft acceleration. For example, the crankshaft acceleration may be generated by modulating an air/fuel ratio in a selected cylinder across a range of air/fuel ratios while keeping the engine at stoichiometry.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A system and method for engine control and diagnostics are described. In one example, a catalyst is modeled as a non-linear integrator. The method may improve engine air-fuel diagnostics.

Abstract: A system for an internal combustion engine of a vehicle is disclosed. In one example, characteristics of an oxygen sensor are a basis for determining degradation of a temperature sensor. In this way, the system can provide redundant exhaust gas temperature sensing.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A method and system for fuel vapor control in a hybrid vehicle (HEV). The HEV fuel vapor recovery system includes a fuel tank isolation valve, which is normally closed to isolate storage of refueling from storage of diurnal vapors. The method for fuel vapor control includes selectively actuating the fuel tank isolation valve during interrelated routines for refueling, fuel vapor purging, and emission system leak detection diagnostics to improve regulation of pressure and vacuum the HEV fuel vapor recovery system.

Abstract: A system for managing fuel-vapor emission from a fuel tank of a vehicle using a vortex-effect flow separator coupled in the fuel-vapor purging system of the vehicle. The warmer-flow outlet of the separator is coupled to the engine intake, and the cooler-flow outlet is coupled to the fuel tank. In this way, less fuel vapor is delivered to the engine intake.

Abstract: Air/fuel imbalance monitoring systems and methods for monitoring air/fuel ratio imbalance of an internal combustion engine are disclosed. In one embodiment, an oxygen sensor is sampled above cylinder firing frequency and a ratio of data from at least one window over a total number of windows is determined. The approach can be used to indicate imbalances between engine cylinders.

Abstract: Air/fuel imbalance monitoring systems and methods for monitoring air/fuel ratio imbalance of an internal combustion engine having a plurality of engine cylinders are provided herein. An example of the method may include routing exhaust gas from a first group of cylinders to an exhaust gas oxygen sensor, and during selected operating conditions, indicating that air/fuel of at least one cylinder in the first group is imbalanced based on a response of the exhaust gas oxygen sensor at frequencies at or above firing frequency of the cylinders in the first group. An example of the system may include an exhaust gas oxygen sensor positioned in such a way that exhaust gas from the group of engine cylinders are routed to the exhaust gas oxygen sensor, and a controller configured to during selected operating conditions, indicate that air/fuel of at least one cylinder in the group is imbalanced based on a response of the exhaust gas oxygen sensor at frequencies at or above firing frequency of the cylinders in the group.

Abstract: A system for managing fuel vapors generated in a fuel system of a vehicle, the fuel system including a fuel tank includes a flow separator comprising an inlet to which a gas flow having fuel vapors is admitted, at least two outlets, and an internal cavity, the inlet, the outlets, and the internal cavity configured to separate the gas flow, with at least one outlet flow becoming warmer and at least one outlet flow becoming cooler than the inlet flow; a first path coupling the warmer outlet to an engine of the vehicle; a second path coupling the cooler outlet to the fuel tank; and a third path coupling the fuel tank to the inlet.