A method for operating a hybrid vehicle, wherein the hybrid vehicle has an electric engine, an electric traction energy accumulator interacting with the electric engine, an internal combustion engine, and a fuel tank interacting with the internal combustion engine, includes starting from a purely electric driving mode in which the internal combustion engine is shut down and in which a shut-off valve of the fuel tank is closed, opening the shut-off valve of the fuel tank and starting up the internal combustion engine depending on defined operating conditions. The defined operating conditions include a current charging state of the traction energy accumulator and a current pressure in the fuel tank.

Methods and systems are provided for diagnosing a variable displacement engine. In one example, a method includes during steady-state vehicle cruising, operating an engine with one or more cylinders of the engine deactivated, commanding the one or more cylinders to reactivate, and indicating cylinder valve actuator degradation responsive to a fuel usage change following the command to reactivate.

The present invention relates to a method for diagnosing a failure of a power stage of an electronic waste gate actuator (EWGA). According to the present invention, whether the failure of the power stage of the EWGA occurs is determined by confirming, by an engine control unit (ECU), information on the failure of the power stage transferred from an EWGA driver IC at the time of EWGA position learning, after an engine is turned off. By doing so, even when a turbo-charger is not used for a long time, whether the failure of the power stage of the EWGA occurs may be diagnosed for every driving cycle, such that a failure of the ECU may be prevented in advance and unnecessary replacement of components may be prevented, thereby decreasing maintenance costs for a vehicle.

Methods and systems are provided for reducing lean air-fuel ratio excursions due to degradation of a port injector while fueling an engine via each of port and direct injection. During a PFDI mode of engine operation, responsive to an indication of port injector degradation, such as due to circuit or injector power issues, intake airflow is limited by reducing the opening of an intake throttle. Air flow is limited to be based only on the direct injected fuel fraction, and independent of the commanded port injected fuel fraction.

Provided is an electronic control device capable of performing abnormality diagnosis of a digital input circuit without modifying the circuit configuration. Included are: an external connection terminal to which an external power supply is connected; a first capacitor having one end connected to the external connection terminal and the other end connected to circuit ground; a microcomputer having a D/I port which is an input/output port and to which a voltage of the external connection terminal is input; an RC filter provided between the D/I port and the first capacitor, the RC filter including a first resistor and a second capacitor; and a second resistor for dividing an output voltage of the D/I port together with the first resistor and applying the divided voltage to one end of the first capacitor, in which the microcomputer outputs a predetermined voltage from the D/I port and diagnoses a connection condition of the external connection terminal on the basis of a voltage input to the D/I port after the first capacitor is charged with the predetermined voltage.

Methods and systems are provided for diagnostics of an exhaust tuning valve during vehicle-off conditions. In one example, the engine may be reverse rotated, unfueled while the position of the exhaust is varied and an intake air flow is estimated at each position of the exhaust tuning valve. The exhaust tuning valve may be diagnosed based on a change in air flow with the variation in the position of the exhaust tuning valve.

Methods and systems for diagnosing operation of a compression ratio adjusting mechanism are described. In one example, an output of a pressure sensor is sampled and an assessment of the engine's present compression ratio is made after adjusting sampling of the output. Engine operation may be adjusted responsive to whether or not degradation of the compression ratio adjusting mechanism is indicated.

Disclosed are a method and apparatus for diagnosing a fault in a CVVD system. The method includes collecting information necessary to determine whether a fault diagnosis mode entry condition of the CVVD system is satisfied, determining whether the fault diagnosis mode entry condition is satisfied based on the collected information, calculating prediction duration corresponding to a current engine RPM and manifold pressure when the fault diagnosis mode entry condition is satisfied, calculating current duration based on an output value of a motor sensor for detecting the RPM of the duration control motor of the CVVD system, comparing the manifold pressure-based prediction duration D1 with the sensor output-based duration D2, and determining an error of the motor sensor or whether the CVVD system has failed by comparing a duration difference cumulative value, that is, a cumulative value of difference values between the D1 and D2, with a previously stored threshold.

An engine fuel delivery system, prognosis system, and method of conducting a fuel pump solenoid prognosis are provided. The engine fuel delivery system includes a fuel pump having a pumping chamber, a closeable inlet valve (such as a fuel pump control solenoid), and a fuel rail to communicate pressurized fuel received from the fuel pump to at least one engine cylinder. The engine fuel delivery system, prognosis system, and method are configured to determine a solenoid current feedback of a fuel pump control solenoid and a variation in the feedback. The fuel delivery system, prognosis system, and method are further configured to indicate a potential solenoid electrical connection fault if the solenoid current feedback is less than a predetermined current threshold and less than a predetermined variation threshold, and to indicate a potential solenoid weakened electromagnetic field fault if the solenoid current feedback is greater than the predetermined variation threshold.

Fuel injector wear methodologies for use with internal combustion engines include a method that determines power of the engine and/or fuel flow of a fuel injector(s) associated with a cylinder the engine; obtains a duration of a fuel injection event from the injector(s) associated with the cylinder(s) of the engine; compares the power, the fuel flow, and/or the duration with a reference value; and then adjusts the fuel injection timing of the fuel injector(s), based on the comparison. Another method adjusts operation of an engine includes: comparing two (or more) engine models, wherein one model is related to a fuel injection event duration of the engine or a modeled fuel quantity being supplied to the engine and then adjusting the fuel injection timing of a fuel injector(s) of the engine, based on the comparison.