A supercharging system includes a waste gate valve and an ECU. The ECU is configured to: calculate a first parameter and a second parameter, each of which has a positive correlation with an intake air amount; obtain a first difference by subtracting a first boost pressure from a second boost pressure; obtain a second difference by subtracting the first parameter from the second parameter; obtain a quotient by dividing the first difference by the second difference; and determine that a malfunction occurs in the waste gate valve when the quotient is larger than a threshold value.

Disclosed are a method and a system for feedback-controlling including controlling a current supply unit in a controller so that an output applied to a driving unit from the current supply unit is repeatedly turned on/off by predetermined period and duty. The method also includes feedback-controlling of an output value of the controller applied to the current supply unit from the controller so that the output of the current supply unit follows a target value. The feedback-controlling includes an integration control process and stops the integration control process in the period that the current supply unit turns off the output thereof.

An object is to carry out an abnormality diagnosis for a variable compression ratio mechanism without adding any special hardware configuration for estimating a compression ratio. An abnormality diagnostic device for a variable compression ratio mechanism adapted to be applied to an internal combustion engine comprises a controller configured to calculate a predetermined rotational speed difference which is a rotational speed difference, between an engine rotational speed at a predetermined crank angle before or after compression top dead center and an engine rotational speed in the vicinity of the compression top dead center for a predetermined cylinder at the time of carrying out fuel cut processing, set a reference range of the predetermined rotational speed difference, and make a diagnosis that abnormality has occurred in the variable compression ratio mechanism when the predetermined rotational speed difference is out of the reference range.

An EGR apparatus includes an EGR passage to allow part of exhaust gas discharged from an engine to an exhaust passage to flow as EGR gas into an intake passage; an EGR valve to regulate an EGR flow rate in the EGR passage; various sensors for detecting an engine running state; and an ECU to control the EGR valve based on the detected running state to diagnose abnormality in the EGR valve. The ECU calculates a reference intake pressure according the detected engine rotation speed and load by reference to a reference intake pressure map showing a relationship of the reference intake pressure to engine rotation speed, and engine load, and determine whether or not the EGR valve has abnormality in opening/closing by comparing the reference intake pressure with the detected intake pressure.

A variable compression ratio internal combustion engine is provided with a variable compression ratio mechanism in which a mechanical compression ratio of the internal combustion engine changes in accordance with a rotational position of a control shaft, a low compression ratio side stopper, a high compression ratio side stopper, a sensor for detecting a rotational position of a drive shaft of an actuator, and an arm press-fitted onto the drive shaft. Relative rotation between the arm and the drive shaft occurs when a torque exceeding an upper-limit torque has been applied. The drive shaft or the control shaft is caused to move to restriction positions restricted by the respective stoppers, and then a diagnosis on the presence or absence of the relative rotation is executed, based on the detected values at the respective restriction positions.

Methods and apparatuses are provided for detecting a defective internal clock signal. A signal transformer receives a clock signal having a duty cycle and a frequency and converts with the signal transformer the clock signal into a monitoring signal having a peak value related to the duty cycle and to the frequency of the clock signal. A detector is connected to the signal transformer to receive the monitoring signal and generates an error signal when the peak value of the monitoring signal is outside a predefined range.

Systems and methods are provided for controlling exhaust gas recirculation (EGR). In one example, an engine system includes a first EGR valve coupling an exhaust manifold to an engine exhaust system, a second EGR valve coupling the exhaust manifold to an engine intake system, and a control unit. The control unit selectively adjusts a position of the first EGR valve based on a target amount, and adjusts a position of the second EGR valve based on the target amount and a position of the first EGR valve. Responsive to a first degradation condition of the first EGR valve, the control unit adjusts the position of the second EGR valve based on the target amount and based on a pressure of the first exhaust manifold, and responsive to a second degradation condition of the first EGR valve, adjusts the position of the second EGR valve based on the target amount.

A method and a system for detection of torque deviations of an engine (101) in a vehicle (100). A measurement (201) is made of actual measured values D.sub.act related to a behavior of at least one parameter which is related to an actual torque M.sub.eng.sub._.sub.act delivered by the engine (101). This actual torque M.sub.eng.sub._.sub.act is delivered here by the engine (101) in consequence of a torque M.sub.eng.sub._.sub.req demanded from the engine (101). A comparison (202) is then made of the actual measured values D.sub.act which are related to the behavior of the at least one parameter with previously determined measured values D.sub.ref of correspondingly at least one respective parameter related to the actual torque M.sub.eng.sub._.sub.act. The previously determined measured values D.sub.ref will here have been determined during normal operation of the vehicle (100). Detection is then made of whether the actual measured actual torque M.sub.eng.sub._.sub.act deviates from the demanded torque M.sub.engj-eq. The detection is based here on the comparison of the actual measured values D.sub.act with the previously determined measured values D.sub.ref.

An internal combustion engine includes a port injector that injects fuel into an intake port and a direct injection injector that injects fuel directly into a combustion chamber. When the internal combustion engine is in a low load condition while requiring fuel injection, a controller stops fuel injection through the port injector so that an entire required fuel injection amount is injected through the direct injection injector. As a result of this processing, the fuel pressure of the direct injection injector is reduced quickly in the low load condition.

A control device for a WG actuator includes a feedback control unit for performing feedback control on the WG actuator in such a way that the position of a shaft detected by a position sensor gets close to a target position, and an abnormality detecting unit for providing an instruction to move the shaft in an axial direction for the feedback control unit, and for detecting an abnormality in the WG actuator on the basis of a result of a movement of the shaft, the movement being detected by the position sensor while the feedback control unit performs the instruction.