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 fault diagnostic system of a vehicle includes a noise module that determines a noise value based on a plurality of differences between samples of a pressure signal generated by a pressure sensor located in a positive crankcase ventilation (PCV) system of an engine. A signal module determines a signal value based on the samples of the pressure signal generated by the pressure sensor located in the PCV system of the engine. A diagnostic value module determines a diagnostic value based on one of: (i) a product of the noise value and the signal value; and (ii) a sum based on the noise value and the signal value. A fault module selectively diagnoses a fault in the PCV system based on the diagnostic value and generates a malfunction indicator within a passenger cabin of the vehicle in response to the diagnosis of the fault in the PCV system.

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.

Disclosed is a method and a unit (10) for the regulation or control of a fluid pressure, having at least one housing section (13, 14) and a switching film (22) connected to the at least one housing section (13, 14) for switching at pressure differentials of 1 to 250 mbar, preferably from 1 to 100 mbar, relative to an ambient pressure acting on the switching film (22), and for the regulation, release or blocking of a flow of the fluid between an inlet (28) and a discharge (30) for the fluid. The switching film (22) is made out of a polymer material having fluorine and carbon. In this arrangement, a hole cross-section (40) of the at least one housing section (13, 14) is closed off by the switching film (22).

A method for diagnosing a crankcase system, comprising a determination of a signal waveform of an intake pressure in an intake area of a crankcase, a determination of a signal waveform of a second pressure in an area of the crankcase downstream of the intake area, a calculation of a similarity between the signal waveform of the intake pressure and the signal waveform of the second pressure, and a comparison of similarity with a similarity setpoint range. A deviation of similarity from the similarity setpoint range indicates an improper condition of the crankcase system. Furthermore, a crankcase system, a vehicle and a computer program product are provided.

Systems and methods (e.g., a method for controlling and/or operating a compressor) are provided that includes the steps of monitoring a crankcase pressure of a first compressor; analyzing the monitored crankcase pressure that includes calculating an average of the crankcase pressure over a time period and comparing the average of the crankcase pressure over the time period to a nominal crankcase average pressure; identifying a condition of the first compressor based on the analysis of the monitored crankcase pressure; and adjusting operation of a second compressor to compensate for the first compressor in response to identifying the condition of the first compressor based on the analysis of the monitored crankcase pressure. (The method may be carried out automatically or otherwise by a controller.)

A Positive Crankcase Ventilation (PCV) channel disconnect detection device and method is provided for an engine having a crankcase, an intake system for delivering metered air to the engine, and a PCV channel for containing PCV gas flow between the crankcase and the intake system and having a first end and a second end. The PCV channel disconnect detection device includes a detection channel that supplies unmetered air surrounding one of the ends of the PCV channel to a post-throttle portion of the intake system. The detection channel is inoperable in response to a vacuum in the post-throttle portion of the intake system if the PCV channel connection is connected. The detection channel is operable in response to the vacuum in the post-throttle portion of the intake system if the PCV channel is disconnected. The detection channels may be configured to bypass all flow restrictions in the PCV system.

Methods for indicating whether a crankcase of an engine is breeched are provided. One example method comprises restricting a communication of the crankcase with atmosphere, acting to increase or decrease a crankcase pressure, and indicating whether the crankcase is breeched based on the crankcase pressure. Another example method comprises sensing a crankcase pressure component, and indicating whether the crankcase is breeched based on the crankcase pressure component, the crankcase communicating with atmosphere via a conduit, a restrictedness of the conduit responsive to one or more of a crankcase pressure and a signal from an electronic control unit of the motor vehicle. Still other examples provide more particular methods for indicating whether the crankcase is breeched, and example configurations that enable the various methods.

Various methods and systems are provided for diagnosing an exhaust gas recirculation valve based on crankcase pressure. In one example, a method comprises indicating a condition of a valve disposed in a first exhaust passage downstream from a cylinder exhaust valve based at least in part on a crankcase pressure.

Methods and systems are provided for implementing a diagnostic technique for a positive crankcase ventilation (PCV) assembly. In one example, the method includes generating an estimated crankcase pressure at the location of a crankcase pressure sensor based on a nominal model and a faulted model of a PCV system that is generated by a controller. The method further includes diagnosing a PCV system component based on a difference between the estimated crankcase pressure and an input from the crankcase pressure sensor; and responsive to the crankcase pressure sensor having a faulted diagnosis, triggering a sensor degradation indicator.