Systems and methods for operating an internal combustion engine based on output of an intake manifold pressure sensor and output of an in cylinder pressure sensor are described. The systems and methods provide a way of determining cylinder air charge so that a fuel injector has sufficient time to provide a desired amount of fuel to a cylinder during a cycle of the cylinder.

A fuel supply system includes an electronic control unit that outputs a target fuel pressure for controlling a low-pressure pump and an engine status, and a fuel pump controller (FPC) that generates a drive signal for driving the low-pressure pump based on the target fuel pressure. The FPC is configured to obtain an actual fuel pressure, to set a duty ratio and to perform a feedback control for the actual fuel pressure to follow the target fuel pressure, and to set a lower limit guard value based on the engine status. The lower limit guard setter sets a duty ratio of 0% as the lower limit guard value when the engine status indicates a stop of the engine.

The present invention obtains a humidity measuring device capable of performing self-diagnosis with high reliability. This humidity measuring device 20 has a diagnosis processing unit 25 for performing self-diagnosis by using gas temperatures and gas humidities before and after a gas in an ambient atmosphere to be measured is heat-controlled. The diagnosis processing unit has a diagnosis start determining unit 26 for determining whether the self-diagnosis can be started on the basis of an exchange state in the ambient atmosphere to be measured and the gas temperature and the gas humidity before the gas in the ambient atmosphere to be measured is heat-controlled, and a diagnosis continuation determining unit 28 for determining whether the self-diagnosis can be continued on the basis of the gas temperature and the gas humidity that are heat-controlled during the self-diagnosis.

Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, the engine system may be installed in a hybrid vehicle, and, in response to a request to restart the engine while the vehicle is being propelled via motor torque only, the engine may be rotated unfueled via the motor torque at less than cranking speed while at least partially opening a valve disposed in a passage coupled between the first exhaust manifold and the intake passage. In another example, in response to the request to restart the engine, all exhaust valves of a second set of exhaust valves coupled to the second exhaust manifold may be deactivated.

Systems and methods for determining operation of a cylinder deactivating/reactivating device are disclosed. In one example, a warm engine is rotated without being supplied fuel to determine the presence or absence of valve actuator degradation. Degraded valve actuators may be determined when there is a lack of a temperature rise in the engine exhaust system.

A control apparatus includes a diesel engine having a throttle valve and a fuel injection valve, an electric driving machine that assists in drive of the engine, and a controller configured to stop the engine automatically when a first condition for automatically stopping the engine is established during an operation of the engine. At this time, the controller is configured to operate the throttle valve to a closing side in response to establishment of a second condition that is established prior to establishment of the first condition, and stop supply of fuel by the fuel injection valve in response to subsequent establishment of the first condition.

Methods and systems are provided for conducting an evaporative emissions test diagnostic on a vehicle fuel system and evaporative emissions control system during engine-on conditions. In one example, a first fuel vapor storage device is separated from a second fuel vapor storage device by a one-way check valve, thus preventing loading of the first fuel vapor storage device during conditions such as refueling operations, diurnal temperature fluctuations, or from running-loss vapors from a vehicle fuel tank. In this way, the evaporative emissions test diagnostic may be conducted during a cold-start event where an exhaust catalyst is below a predetermined threshold temperature required for catalytic oxidation of hydrocarbons in the engine exhaust, without increasing undesired exhaust emissions.

Systems and methods for operating an internal combustion engine based on output of an intake manifold pressure sensor and output of an in cylinder pressure sensor are described. The systems and methods provide a way of determining cylinder air charge so that a fuel injector has sufficient time to provide a desired amount of fuel to a cylinder during a cycle of the cylinder.

Methods and systems are provided for removing moisture from an engine exhaust system. In one example, a method includes, during a vehicle key-off condition, in response to a higher than threshold exhaust moisture level and a lower than threshold engine run time during an immediately prior drive cycle, operating an electric air compressor to remove the moisture accumulated in the exhaust manifold.

Provided is a control device of a hybrid vehicle powered by an internal-combustion engine and a motor, wherein a catalyst that purifies exhaust gas is located in an exhaust passage of the internal-combustion engine, and the control device comprises: a learning unit configured to, during operation of the internal-combustion engine, learn a parameter for controlling a rotation speed of the internal-combustion engine so that a rotation speed of the internal-combustion engine during idling operation is equal to a target rotation speed; and a controller configured to stop the internal-combustion engine when a state where a correction amount of the parameter to cause the rotation speed during idling operation to be equal to the target rotation speed is equal to or greater than a predetermined value continues for equal to or greater than a predetermined time period, the correction amount being obtained by learning by the learning unit.