Abstract: Methods and systems for diagnosing a multiple cylinder engine are provided herein. An exemplary method of diagnosing an internal combustion engine system having a multi-cylinder internal combustion engine is described. In one example, cylinder air-fuel imbalance is determined from the squared value of a difference of two values.

Abstract: Method and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions. One example method comprises, adjusting a brake torque applied to a deactivated rotating engine after an engine restart request, the brake torque applied to slow the engine to at least a predetermined threshold speed without stopping the engine, and engaging a starter to the still rotating engine to increase the engine speed and restart the engine.

Abstract: Methods and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions and selectively reactivated during engine restart conditions. One example method comprises, during an engine restart from an idle stop, performing a first combustion event in a cylinder with a piston at an engine crankshaft position that is after a crankshaft position at which said cylinder's exhaust valve opens, and before a crankshaft position at which the cylinder's intake valve closes, during a cycle of said cylinder. In this way, inaccuracies in cylinder aircharge estimation may be reduced, thereby also reducing air-fuel ratio errors and improving the quality and repeatability of engine restarts.

Abstract: A method is provided for controlling an engine having two cylinders, one of which having an adjustable valve. The method comprising performing a combustion in two cylinders having pistons, the combustions for said cylinders occurring during a common stroke of the pistons; increasing a number of strokes in a cycle of one of the two cylinders; and returning operation of the one of the two cylinders to four strokes, so that combustion of the one of the two cylinders occurs sequentially from the other of the two cylinders.

Abstract: Various systems and methods for an engine system which includes a throttle turbine generator having a turbine which drives an auxiliary generator and disposed in a throttle bypass are described. In some examples, a throttle bypass valve is controlled to adjust airflow through the throttle bypass responsive to airflow to cylinders of the engine. In other examples, an operating parameter such as throttle position is controlled based on transient operating conditions of the engine. In still other examples, charging of a battery is coordinated between the auxiliary generator and a primary generator.

Abstract: Various systems and methods for an engine system which includes a throttle turbine generator having a turbine which drives an auxiliary generator and disposed in a throttle bypass are described. In some examples, a throttle bypass valve is controlled to adjust airflow through the throttle bypass responsive to airflow to cylinders of the engine. In other examples, an operating parameter such as throttle position is controlled based on transient operating conditions of the engine. In still other examples, charging of a battery is coordinated between the auxiliary generator and a primary generator.

Abstract: Various example approaches are described, one of which includes a method for adjusting relative delivery of liquid and gaseous fuel to a cylinder of the engine to effect rapid changes in cylinder air charge via changes in the displacement of fresh air by the gaseous fuel. In one particular approach, turbocharger lag is addressed by decreasing gaseous fuel injection while increasing liquid fuel injection to increase cylinder fresh air over and above any changes to fresh air via the throttle, wastegate, and/or turbocharger.

Abstract: Various systems and methods are described for operating an engine in a vehicle in response to a driver performance/economy mode. One example method comprises delivering a first fuel to a cylinder of the engine from a first injector, delivering a second, different, fuel to the cylinder of the engine from a second injector, varying a relative amount of said first and second fuel as an operating condition varies; and adjusting delivery of at least said second fuel based on a driver-selected performance mode.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, the fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, intermittently adjusting a restriction in the fuel vapor recovery system during boosted conditions, and indicating degradation based on one or more of a change in a pressure value, or based on a change in flow in the fuel vapor recovery system.

Abstract: A system for starting an engine is described. In one example, the engine is supplied two fuels via two injectors. The method may improve engine starting and reduce engine emissions.

Abstract: Method and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions. One example method comprises, adjusting a brake torque applied to a deactivated rotating engine after an engine restart request, the brake torque applied to slow the engine to at least a predetermined threshold speed without stopping the engine, and engaging a starter to the still rotating engine to increase the engine speed and restart the engine.

Abstract: Methods and systems are provided for controlling a vehicle system including an engine that is selectively deactivated during engine idle-stop conditions and selectively reactivated during engine restart conditions. One example method comprises, during an engine restart from an idle stop, performing a first combustion event in a cylinder with a piston at an engine crankshaft position that is after a crankshaft position at which said cylinder's exhaust valve opens, and before a crankshaft position at which the cylinder's intake valve closes, during a cycle of said cylinder. In this way, inaccuracies in cylinder aircharge estimation may be reduced, thereby also reducing air-fuel ratio errors and improving the quality and repeatability of engine restarts.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, the fuel vapor recovery system coupled to an engine intake of a boosted internal combustion engine. One example method comprises, intermittently adjusting a restriction in the fuel vapor recovery system during boosted conditions, and indicating degradation based on one or more of a change in a pressure value, or based on a change in flow in the fuel vapor recovery system.

Abstract: Various systems and methods are described for operating an engine in a vehicle in response to a driver performance/economy mode. One example method comprises delivering a first fuel to a cylinder of the engine from a first injector, delivering a second, different, fuel to the cylinder of the engine from a second injector, varying a relative amount of said first and second fuel as an operating condition varies; and adjusting delivery of at least said second fuel based on a driver-selected performance mode.

Abstract: As one example, a vehicle propulsion system is provided. The system includes: an engine with an intake air compressor and an exhaust gas turbine. Further, a control is provided to operate the compressor at a different speed than the turbine, at least under an operating condition, and to adjust an amount of opening overlap between engine valves in response to a rotational speed of the compressor.

Abstract: A system for starting an engine is described. In one example, the engine is supplied two fuels via two injectors. The method may improve engine starting and reduce engine emissions.

Abstract: A tunable bandpass filter (10) is provided. An RF signal is provided at an input of the tunable bandpass filter, and a level shifted control signal (V1, V2) inputted to the tunable bandpass filter (10) switches a first arrangement and a second arrangement of one or more tuning portions (15, 17-1, 17-2, 17-3) in or out of the tunable bandpass filter using a GaAs FET switch. The first arrangement is coupled to the second arrangement using an inductor (13). An RF signal having a desired predetermined frequency at an output of the tunable bandpass filter (10) is produced by the switching. The tuning portions include the GaAs FET switch (15), a first capacitor (17-1) connected at a first signal terminal of the GaAs FET switch and a second capacitor (17-2) connected between a second signal terminal of the GaAs FET switch and ground. Each of the tuning portions can be arranged in parallel with one another.

Abstract: Various systems and methods are described for operating an engine in a vehicle in response to a driver performance/economy mode. One example method comprises delivering a first fuel to a cylinder of the engine from a first injector, delivering a second, different, fuel to the cylinder of the engine from a second injector, varying a relative amount of said first and second fuel as an operating condition varies; and adjusting delivery of at least said second fuel based on a driver-selected performance mode.

Abstract: A system for starting an engine is described. In one example, the engine is supplied two fuels via two injectors. The method may improve engine starting and reduce engine emissions.

Abstract: Methods and systems are provided for expediting engine spin-down in an engine that is shutdown during engine idle-stop conditions and restarted during restart conditions. In one example, the method comprises, during an automatic engine idle-stop, turning off spark, operating a first cylinder with a rich ratio of air to injected fuel richer than a rich flammability limit, operating a second cylinder with a lean ratio of air to injected fuel leaner than a lean flammability limit, and mixing un-combusted exhaust from the first and second cylinders with exhaust, the exhaust mixture being substantially stoichiometric.