A method and apparatus for diagnosing an engine system are provided. An apparatus for diagnosing an engine system including a continuous variable valve duration (CVVD) apparatus according to an exemplary embodiment of the present invention may include: an accelerator pedal position detector configured for detecting a position of an accelerator pedal; a brake pedal position detector configured for detecting a position of a brake pedal; a vehicle speed detector configured for detecting a speed of a vehicle; an intake pressure detector configured for detecting an intake pressure; and a controller configured for determining whether a fuel cut condition is satisfied and determining whether the CVVD apparatus is in a failure state when the fuel cut condition is satisfied.

A method of determining a learning area of injector opening duration according to the present exemplary embodiment divides an entire control area for controlling opening duration of an injector into a learning map area which needs learning and a reference map area which uses an already prepared reference map as is without learning, and a period from a minimum injection time to a minimum linear injection time of the injector is determined as the learning map area, and a period from the minimum linear injection time to a maximum injection time is determined as the reference map area.

Methods and systems are provided for diagnosing a positive crankcase valve during a vehicle key-off event. In one example, a method may include controlling a fluid flow from a crankcase of an engine to an intake manifold of the engine via a positive crankcase ventilation valve, and indicating whether the positive crankcase valve is stuck open responsive to spinning the engine unfueled in a reverse direction, and indicating whether the positive crankcase valve is stuck closed responsive to spinning the engine fueled but without spark in a forward direction. In this way, functionality of a positive crankcase ventilation valve may be diagnosed effectively during key-off conditions, which may prevent or reduce engine complications arising from a stuck open or stuck closed positive crankcase valve.

A method for identifying faulty components of a fuel injection system is disclosed, wherein a secondary injection is performed individually by each injector during a test routine, after the secondary injection several predefined parameters of the fuel injection system are determined, and a combined assessment of the determined parameters is used to draw conclusions about whether or not components of the fuel injection system are faulty.

A method and apparatus are disclosed for detecting a clogging of a fuel injector of an internal combustion engine. Each fuel injector of the plurality of fuel injectors may be tested for a clogging. A test injector is switch off. A requested value of a fuel quantity to be injected by the other fuel injectors of the plurality of fuel injectors is adjusted to operate the internal combustion engine in an idle mode. A difference is calculated between the requested value of the fuel quantity and a reference value of the fuel quantity to be injected by all the fuel injectors of the plurality of fuel injectors to operate the internal combustion engine in idle mode. The calculated difference for each test injector is used to identify if the test injector is clogged.

Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

A starter controller incorporated in a starter control system for controlling actuation of a first starter and a second starter to start an engine. The second starter is an alternating-current (AC) starter. The starter control system actuates the first starter in response to an engine start-up request, deactivates the first starter before completion of engine start-up, and activates the second starter while the second starter is being rotated by rotation of an engine rotary shaft. In the starter controller, a determination unit is configured to, under a condition where the engine rotary shaft is rotating after deactivation of the first starter, determine whether or not recognition of rotation of the second starter is complete. A fail-safe unit is configured to, if the recognition of rotation of the second starter is complete, perform predefined fail-safe processing responding to an abnormality in the second starter.

On-board diagnostic monitoring of a two-stroke cycle, opposed-piston engine includes diagnostic monitoring of an air handling system equipped with a supercharger to determine whether the supercharger is functioning properly.

A method for predefining a current through a solenoid coil of a solenoid valve, a closing point in time of the solenoid valve being detected with the aid of a sensor, a sensor value being monitored, and, when a premature closing of the solenoid valve is identified based on the monitored sensor value, the current through the solenoid coil of the solenoid valve is increased.

A method to adjust an oil control valve actuation response time using cylinder valve diagnostic results includes commanding an engine cylinder to deactivate/reactive when conditions are met and then detecting if a deactivation/reactivation response time failure has occurred by analyzing the cylinder diagnostics results. If a predetermined number of failures are detected at the cylinder within a predetermined number of engine cycles then the engine controller operates to adjust the oil control valve response time to improve the response time accuracy.