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.

Method and apparatus for detecting drift of pilot, wherein the method includes: measuring two rotation speeds corresponding to each detection point of at least one detection point when an engine equipped with an injector is in an idle state, wherein the detection point is point(s) of an injection curve measured under the condition that a current injection pressure is applied to the injector when there is no drift of pilot in the injector, energizing time indicated by the point(s) being less than a predefined value, one rotation speed is a rotation speed of the engine during a certain working cycle of a cylinder injected by the injector, the injector being energized for an energizing time indicated by that detection point in a pilot period of the cycle, and another rotation speed is a rotation speed of the engine during an another working cycle of the cylinder, the injector not being energized in the pilot period of the cycle; calculating a current engine rotation speed change corresponding to the detection point; acquiring an indication value corresponding to the detection point; and determining whether there is drift of pilot in the injector, based on the indication value.

A system for ascertaining operational status of an electrically-actuated valve comprises a valve-diagnostic device, which comprises: a mechanical sensor for detecting movement of a movable part of the electrically-actuated valve relative to a stationary part and outputting a mechanical sensor signal; and an electrical sensor for detecting an electrical characteristic associated with the operation of the electrically-actuated valve and outputting an electrical sensor signal. The system also comprises a data analyzer connected to the valve-diagnostic device to receive the mechanical sensor signal and the electrical sensor signal, and configured to display a corresponding output.

Methods and systems are provided for reducing or avoiding engine hesitation and/or stall during engine idle conditions. In one example, a method may include inferring an engine idle condition, and in response, controlling a speed of an engine to a compensated engine idle speed that is a function of an extent to which a canister purge valve that regulates an amount of fluid flow to the engine from a fuel system and/or an evaporative emissions system, is degraded. In this way, an amount of fuel utilized to compensate for the degraded canister purge valve may be proportionate to the extent to which the canister purge valve is degraded.

Methods and systems are provided for diagnosing valve operation during a cylinder deactivation event in a variable displacement engine. Crankshaft acceleration data is captured during an exhaust stroke of a deactivated cylinder and compared to a calibrated map of crankshaft acceleration data for the given cylinder. Based on the comparison, it may be indicated that the deactivation of the exhaust valve of the given cylinder is degraded, and that the exhaust valve is open when commanded closed.

A method for diagnosing an engine system including a continuous variable valve duration (CVVD) apparatus, a driving unit of the CVVD apparatus including a first driving unit and a second driving unit, a CVVD position detector configured to detect a position of the CVVD apparatus, a camshaft position detector configured to detect a position of a camshaft, a front lambda detector configured to detect a lambda value at front of intake valve, and a controller may include the steps of starting the engine, detecting measured values of the front lambda detector during combustion of first to fourth cylinders (first to fourth lambda values), determining whether CVVD driving unit is misaligned according to the detected first to fourth lambda values, and generating a warning notification when the CVVD driving unit is determined to be misaligned.

Methods and systems are provided for diagnosing an exhaust waste-gate valve via an electric boost assist motor of an electric turbocharger. Degradation of the waste-gate valve is inferred based on the motor torque profile of the motor after commanding the waste-gate valve to an open or closed position on a torque transient. Deviation of the motor torque profile from the expected profile is used to infer if the valve is stuck open or closed, and actions are taken accordingly.

Methods and systems are provided for reducing or avoiding engine hesitation and/or stall during engine idle conditions. In one example, a method may include inferring an engine idle condition, and in response, controlling a speed of an engine to a compensated engine idle speed that is a function of an extent to which a canister purge valve that regulates an amount of fluid flow to the engine from a fuel system and/or an evaporative emissions system, is degraded. In this way, an amount of fuel utilized to compensate for the degraded canister purge valve may be proportionate to the extent to which the canister purge valve is degraded.

An internal combustion engine control device that can ensure diagnosis of whether a fuel injection cut function normally works and that further permits startup of an internal combustion engine in a case in which the fuel injection cut function normally works is provided. To attain the internal combustion engine control system, the startup of the internal combustion engine is prohibited when carrying of a diagnostic monitoring current based on a diagnostic drive signal related to each of fuel injection valves to each of fuel injection valves in a case of transmitting a drive prohibition signal related to each of fuel injection valves to a fuel injection valve drive circuit before the startup of the internal combustion engine and transmitting the diagnostic drive signal related to each of fuel injection valves to the fuel injection valve drive circuit. By transmitting the diagnostic drive signal related to each of the fuel injection valves to the fuel injection valve drive circuit and monitoring whether the diagnostic monitoring current based on the diagnostic drive signal is carried to each of fuel injection valves, it is possible to ensure diagnosis of whether the fuel injection cut function normally works.

A current control circuit for an ignition system (i.e., igniter current limiter) is disclosed. The current control circuit can reduce a coil current over a soft shut down (SSD) period using an insulated gate bipolar transistor (IGBT) that is controlled by a negative feedback loop, which controls the current limit of the IGBT according to a SSD profile. In order to prevent an unwanted current rise during the soft shut down period, the current control circuit compares a gate voltage of the IGBT to a reference signal and based on the comparison can enable the SSD profile to include a fast ramp. The fast ramp quickly lowers the current limit of the IGBT so that the coil current equals the current limit and can be controlled by the negative feedback loop.