A method for determining the angular position of an engine by a crankshaft sensor and a camshaft sensor. The method includes production by the crankshaft sensor of a revolution event, determination of the angular position of the camshaft by identifying the start-of-tooth and end-of-tooth events following the revolution event, in rapid mode, over at most one revolution of the crankshaft, if a no tooth event occurs after the revolution event and if the determination of the angular position of the camshaft fails, the method continues with a step of determining the angular position of the camshaft by identification, in slow mode, over at least two crankshaft revolutions.

Methods and systems are provided for diagnosing a humidity sensor positioned in an intake system of a vehicle engine system. In one example, a method comprises rotating an engine unfueled in reverse and injecting a fluid into an exhaust system of the engine system, to draw the fluid into the intake system, where a humidity sensor output signal greater than a baseline output signal by a predetermined threshold is indicative of a humidity sensor that is functioning as desired. In this way, a humidity sensor may be periodically rationalized which may prolong engine lifetime by ensuring the engine is operating at optimal parameters.

Methods and systems are provided for a diagnostic of a humidity sensor positioned in an intake of an engine and adjusting engine operation responsive to findings of the diagnostic. In one example, the method may include sealing a vehicle exhaust system of an engine, combusting fuel at cylinders of the engine while flowing gases through the engine in a first direction, and then, flowing the combusted exhaust gases through the engine in a reverse, second direction to the humidity sensor positioned in the intake. The method may further include indicating degradation of the humidity sensor based on the output of the humidity sensor while flowing gases in the first and second directions.

Methods and systems are provided for diagnosing a humidity sensor positioned in an intake system of a vehicle engine system. In one example, a method comprises rotating an engine unfueled in reverse and injecting a fluid into an exhaust system of the engine system, to draw the fluid into the intake system, where a humidity sensor output signal greater than a baseline output signal by a predetermined threshold is indicative of a humidity sensor that is functioning as desired. In this way, a humidity sensor may be periodically rationalized which may prolong engine lifetime by ensuring the engine is operating at optimal parameters.

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 a diagnostic of a humidity sensor positioned in an intake of an engine and adjusting engine operation responsive to findings of the diagnostic. In one example, the method may include sealing a vehicle exhaust system of an engine, combusting fuel at cylinders of the engine while flowing gases through the engine in a first direction, and then, flowing the combusted exhaust gases through the engine in a reverse, second direction to the humidity sensor positioned in the intake. The method may further include indicating degradation of the humidity sensor based on the output of the humidity sensor while flowing gases in the first and second directions.

There is provided a vehicle-mounted control device that, when a restart request is generated during a time interval between the fulfillment of an engine automatic stop condition and complete stop, decreases a charging efficiency of an engine by means of at least one of a throttle valve and an intake valve to prevent an increase in the reverse rotational frequency of the engine, thereby ensuring the durability of the starting device of the engine, and preventing an accelerator response from deteriorating when a restart request based on the accelerator operation is generated. In the vehicle-mounted control device that controls a charging efficiency of the engine on the basis of the requested engine output amount, the engine is automatically stopped when a predetermined automatic stop condition is fulfilled, and a charging efficiency at the time when a restart condition of the engine has been fulfilled on the basis of an engine output request generated during a time interval between the fulfillment of the automatic stop condition and complete stop of the engine is made lower than a charging efficiency for the requested engine output amount.

A method for determining the angular position of an engine by a crankshaft sensor, having the following steps: production by the crankshaft sensor of a signal exhibiting a revolution event, determination of the revolution out of two revolutions, since a crankshaft makes two revolutions per engine cycle for a four-stroke engine, for each no tooth event potentially produced, a change in the direction of rotation of the engine is suspected, and an analysis step is performed which comprises: if, during an inverse window, a further no tooth event is produced, the change in direction of rotation is confirmed.

Methods and systems are provided for improving combustion events during cold-starts of a vehicle engine, where the cold-start events include start/stop events. In one example, a method comprises spinning the engine in a reverse direction in response to an engine pull-down event where a temperature of an intake manifold of the engine is below a threshold, to heat the intake manifold by drawing exhaust system heat to the intake manifold. In this way, combustion may be improved in response to requests to start the engine, which may reduce undesired emissions and which may improve fuel economy.

A method for determining the angular position of an engine by a crankshaft sensor and a camshaft sensor. The method includes production by the crankshaft sensor of a revolution event, determination of the angular position of the camshaft by identifying the start-of-tooth and end-of-tooth events following the revolution event, in rapid mode, over at most one revolution of the crankshaft, if a no tooth event occurs after the revolution event and if the determination of the angular position of the camshaft fails, the method continues with a step of determining the angular position of the camshaft by identification, in slow mode, over at least two crankshaft revolutions.