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: 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: 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.

Abstract: A system for an engine of a vehicle includes methanol and water injection to abate engine knock. The injection is provided directly into the cylinder.

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: 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.

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: As one example, a vehicle propulsion system is provided. The system includes: an 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 method for a boosted engine including first and second injectors includes adjusting boost during a disabled condition of a first injector to compensate for lack of fuel injected from said first injector, said first injector supplying a fuel to a cylinder of said engine; and adjusting boost during a disabled condition of a second injector to compensate for lack of fuel injected from said second injector, said second injector supplying said fuel to said cylinder of said engine.

Abstract: A method is described for starting an internal combustion engine. During a run-up in engine speed of the engine starting, the method includes adjusting intake valve closing timing in response to barometric pressure to provide a desired air amount in the cylinder, with a longer valve opening with respect to crankshaft angle at higher altitudes as compared to a shorter valve opening with respect to crankshaft angle at lower altitudes for a given operating constraint.

Abstract: An engine system includes two spark plugs in a cylinder of an engine. The two spark plugs have different heat ranges in order to address pre-ignition, where only a first spark plug operates during a first condition, and only a second spark plug operates during a second condition.

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: 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: A method for an engine with first and second injectors in a cylinder provides different fuel injection compensation upon reaching minimum pulsewidths of the first and second injectors. When the first injector reaches its minimum pulsewidth, the first injector is disabled. However, when the second injector reaches its minimum pulsewidth, the second injector is maintained active and injection from the first injector is decreased. In this way, sufficient injection from the second injector is maintained in either situation.

Abstract: A method for an engine configured to deliver an actively varying relative ratio of a first and second fuel via a delivery system having a first and second injector for a cylinder of the engine, where the first fuel has a lesser relative amount of alcohol, the method comprising of varying an amount of injection from the first and second injector with operating conditions, when said variation causes said first injector to approach a first minimum opening condition, increasing injection of said second injector and disabling said first injector, and when said variation causes said second injector to approach a second minimum opening condition, avoiding further reduction of said second injector and decreasing injection of said first injector.

Abstract: A system for providing driver feedback is disclosed. In one embodiment, the system provides a driver with feedback in response to a brake pedal and an accelerator pedal. The system may help to increase vehicle fuel economy.

Abstract: Systems and methods are provided for monitoring reverse flow of fuel vapors and/or air through a vehicle fuel vapor recovery system, said 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 method for operating an engine having a first injector for injecting a first fuel into a cylinder of the engine and a second injector for injection a second fuel into said cylinder of the engine, the engine further having at least an exhaust gas oxygen sensor, the method comprising of varying an amount of said first fuel injection in response to said sensor under a first operating condition, and varying an amount of said second fuel injection in response to said sensor under a second operating condition.

Abstract: A method for starting an internal combustion engine with electrically actuated valves, the method comprising during at least a run-up in engine speed of engine starting, adjusting intake valve timing of an electrically actuated valve of a cylinder to provide a desired air amount in said cylinder, based on at least an operating condition of said 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.