An internal combustion engine (1) has a variable compression ratio mechanism (2) that varies a mechanical compression ratio and a variable valve timing mechanism (7) that varies a valve timing of an intake valve (4). When there is a demand to execute reference position learning (step 21) for system calibration of the variable valve timing mechanism (7), the execution of the reference position learning is permitted on the condition that the mechanical compression ratio is higher than a threshold value VCRth (step 22). When any anomaly is present in the variable compression ratio mechanism (2), the reference position learning of the variable valve timing mechanism (7) is prohibited (steps 23 and 25).

Methods and systems are provided for operating a lift pump of an engine fuel system. In one example, a method may comprise predicting when a fuel rail pressure will decrease below a threshold assuming that a lift pump remains off. The method may further comprise powering on the lift pump before the fuel rail pressure decreases below to the threshold to prevent fuel rail pressure from decreasing below the threshold.

In the communication interruption state in which the transmission of a drive control command value DUTY from an engine control unit (ECU) 1 to a fuel pump driver (FPD) 2 is disabled, the FPD 2 is configured so as to drive a fuel pump 4 by using the maximum command value DTYMAX (100%) as a drive control command value DUTY. A stop state of the fuel pump 4 is maintained even if the drive control command value DUTY is the maximum command value DTYMAX when an ignition switch 21 is in the OFF State so as to have stopped the fuel pump 4, while the fuel pump 4 is driven when the ignition switch 21 is in the ON state and the drive control command value DUTY is the maximum command value DTYMAX.

A rotational angle determining device periodically samples a resolver signal output from a resolver receiving an alternating current excitation signal, the sampling being performed at a timing at which the excitation signal reaches a peak or trough value, based on a timer signal to which initial phase alignment is performed with respect to the excitation signal, and then the device performs A/D conversion of a voltage value of the sampled resolver signal, to determine the rotational angle of the rotor of the resolver. The excitation signal is periodically sampled at a predetermined timing based on the timer signal, and a presence or absence of a phase shift between the excitation and timer signals is detected based on a change in A/D converted value AD1n (n=1, 2, . . . ) obtained by A/D conversion of a voltage value of the sampled excitation signal.

A learned neural network in weights using at least the four parameters of the engine load, engine speed, intake pressure inside the intake passage downstream of the throttle valve (12), and amount of intake air fed into the engine as input parameters of the neural network and using a target EGR rate as training data is stored. At the time of engine operation, the learned neural network is used to estimate the target EGR rate from the above parameters and abnormality of the exhaust gas recirculation system is detected based on the difference between the estimated value of the target EGR rate and the target EGR rate.

A method (10) is described for operating a system (12), for example a hydraulic or pneumatic system (12), in which a manipulated variable of an actuator element (16) can be controlled, and in which at least one variable (26) which is dependent on the manipulated variable of the actuator element (16) can be determined, wherein the manipulated variable of the actuator element (16) is modulated with a first periodic signal (22), and wherein a measurement signal (30) which characterizes the at least one variable (26) is evaluated using at least one second periodic signal (47).

An anomaly determination device executes a first anomaly determination process and a second anomaly determination process. The anomaly determination device determines in the first anomaly determination process that an anomaly is present in a link mechanism when a fully-closed-time detection value is outside a closed-side normal range and when a fully-open-time detection value is outside an open-side normal range. The anomaly determination device determines in the second anomaly determination process that an anomaly is present in the link mechanism if the difference between the fully-closed-time detection value and the fully-open-time detection value is outside a normal distance range set in advance when it is not determined in the first anomaly determination process that an anomaly is present in the link mechanism.

A controller for controlling a fuel injection valve and a fuel pressure adjustment mechanism integrates a deposition amount of deposits per unit time, and estimates a deposition amount of deposits on an injection hole of the fuel injection valve. The controller causes the fuel pressure adjustment mechanism to increase a fuel pressure, when the estimated deposition amount exceeds a predetermined value, and corrects the unit deposition amount acquired by the deposition amount estimation according to the set fuel injection timing of the fuel injection valve. The controller corrects such that as compared with the unit deposition amount when the fuel injection timing is set to a first timing away from a top dead center of the piston by a first period, the unit deposition amount decreases when the fuel injection timing is set to a second timing away by a second period longer than the first period.

A controller for controlling a fuel injection valve and a fuel pressure adjustment mechanism sets an air-fuel ratio of a fuel-air mixture to be generated within a combustion chamber to be equal to or leaner than a theoretical air-fuel ratio, based on an operating condition of an engine; drives the fuel injection valve, based on the set air-fuel ratio; estimates a deposition amount of deposits on an injection hole of the fuel injection valve, based on an operating condition of the engine; causes the fuel pressure adjustment mechanism to increase the fuel pressure, when the estimated deposition amount of deposits exceeds a predetermined value; and restricts the fuel pressure from increasing, even when the estimated deposition amount of deposits exceeds the predetermined value, as long as the fuel-air ratio is set to an air-fuel ratio leaner than the theoretical fuel-air ratio.

Methods and systems are provided for conducting a diagnostic on a fuel tank isolation valve that regulates a flow of fuel vapors from a fuel tank to an evaporative emissions system. In one example, a method comprises determining whether the fuel tank isolation valve is stuck in a first open position or a second open position based on a time duration between commanding open a canister purge valve to direct fuel vapors to an engine, and an exhaust gas sensor indicating a rich air-fuel ratio. In this way, appropriate mitigating action may be taken in response to the fuel tank isolation valve being stuck in either the first open position or the second open position.