Methods and systems are provided for pinpointing a source of degradation in a vehicle engine system. In one example, a method includes spinning an engine of a vehicle unfueled in a forward and a reverse direction, in no particular order, and recording a first intake air flow and a second intake air flow, respectively, in an intake of the engine, and where the source of degradation is indicated as a function of both the first air flow and the second air flow. In this way, the degradation of the vehicle engine system may be pinpointed as to being located in the intake manifold, the exhaust system, or the engine.

Systems and methods for operating an engine that may be frequently stopped and restarted are described. In one example, an engine is rotated in small crankshaft angle increments and stopped after the engine is rotated through a predetermined actual total number of crankshaft degrees so that the engine position does not change when the engine reaches a desired position.

Venting of gaseous fuel during operation and after shutdown of an internal combustion engine increases emissions. A vent handling apparatus for a gaseous fuel system of an internal combustion engine comprises an accumulator for storing gaseous fuel; a first valve selectively enabling fluid communication between the accumulator and one of a gaseous fuel communication passage and a gaseous fuel storage vessel, the gaseous fuel communication passage delivering gaseous fuel to the internal combustion engine for combustion; and an apparatus for selectively returning the gaseous fuel from the accumulator to the internal combustion engine for combustion.

There is provided a method of shutting down an engine, the engine having an air intake, and the method having the steps of attaching a valve to the air intake, the valve having an open position that allows air to pass into the air intake; using one or more sensors, detecting one or more predetermined engine conditions indicative of a runaway state; electromagnetically actuating the valve to move to a closed position preventing air from passing into the air intake once the one or more predetermined engine conditions have been detected; and causing the valve to return to the open position once a predetermined safe state has been reached.

Methods and systems are provided for removing moisture from an engine exhaust system. In one example, a method includes, during a vehicle key-off condition, in response to a higher than threshold exhaust moisture level and a lower than threshold engine run time during an immediately prior drive cycle, operating an electric air compressor to remove the moisture accumulated in the exhaust manifold.

Systems and methods for diagnosing operation of a sensor of an exhaust system are presented. In one example, the systems and methods may diagnose operation of the sensor when an engine is combusting air and fuel. Further, operation of the sensor may be diagnosed when the engine is not combusting air and fuel so that vehicle occupants may not be disturbed by the diagnostic.

Methods and systems are provided for monitoring a change in exhaust particulate filter (PF) soot load during an engine non-combusting condition. In one example, a method may include, responsive to a higher than threshold PF temperature immediately prior to an engine shutdown, estimating a rate of soot burn when the engine is no longer combusting, and estimating a soot load on the PF during and at an onset of immediately subsequent engine start based in part on the rate of soot burn.

A work vehicle includes an engine controller for driving an engine, a power supply line, a power supply control line, and a display signal line. When a check switch switchable into a safe position corresponding to safe drive of the engine and a non-safe position is switched to the safe position, the power supply control line renders a power supply relay ON. The display signal line transmits a signal indicative of the switched state of the check switch to a display.

When there is a restart request to an engine, an electronic control unit controls a wastegate valve to a fully open position on condition that a speed of a vehicle is less than a threshold. When the vehicle speed is not less than the threshold, the electronic control unit restarts the engine and controls the wastegate valve in the closing direction until a desired torque is generated.

A method, device and system for detecting and counteracting a runaway condition in a diesel engine system. The diesel engine system includes an inlet for supplying combustion air to a diesel engine, and an exhaust for relieving the diesel engine from exhaust gas. The diesel engine system further includes an exhaust gas recirculation system for selectively allowing exhaust gas from the exhaust to enter the inlet. A first gas flow path actuator is included in the exhaust gas recirculation system, and a second gas flow path actuator is included in the exhaust. The method, as performed by the system, comprises detection of an actual or potential runaway condition, and in response thereto deprives the diesel engine of oxygen. Depriving of oxygen is performed by opening the first gas flow path actuator and closing the second gas flow path actuator to cause stalling of the diesel engine. The depriving is accomplished by maximizing recirculation of exhaust gasses to the engine and increasing pressure drop over the exhaust for a first predetermined period of time.