Systems and methods for diagnosing an exhaust aftertreatment system are provided. A method includes: receiving, by a controller and for each sensor of a plurality of sensors, one or more respective degradation level indicators indicative of one or more failure levels of the sensor, each of the one or more degradation level indicators determined using a corresponding performance parameter; receiving, by the controller and for each sensor of the plurality of sensors, one or more diagnosis threshold values; determining, by the controller, a multipoint diagnosis threshold value using the one or more diagnosis threshold values associated with the plurality of sensors; detecting, by the controller, an operational state of the aftertreatment system by comparing a performance value of the aftertreatment system to the multipoint diagnosis threshold value; and causing, by the controller, an indication of the operational state of the aftertreatment system to be displayed on a display device.

A diagnostic method for a capacitive humidity sensor comprising a heater, and a capacitance-sensing element that individually identifies heater, temperature-sensing element, or capacitance-sensing element degradation. By this method, individual elements of the sensor may be replaced or compensated for to allow for further operation.

The abnormality diagnosis system comprises an air-fuel ratio control means which sets the target air-fuel ratio of exhaust gas to a first set air-fuel ratio set to a first side of a rich side or a lean side, then, when a downstream side output air-fuel ratio is at the first side, switches the target air-fuel ratio to a second set air-fuel ratio set to a second side at the opposite side from the first side. The abnormality diagnosis system calculates the time from when the target air-fuel ratio is switched to when the downstream side output air-fuel ratio starts to change toward the stoichiometric air-fuel ratio based on a differential value of the downstream side output air-fuel ratio and, when the calculated time is a predetermined time or more, judges that a dead time at the downstream side air-fuel ratio sensor is abnormal.

Methods and systems are provided for diagnosing a knock sensor of an engine system by actively inducing knock in an engine cylinder. A laser ignition device is operated in an engine cylinder located closest to the knock sensor while the engine is at rest and with the cylinder parked with an intake valve and an exhaust valve closed to generate and trap heat in the cylinder. Spark timing is advanced in the cylinder on the subsequent restart, which in combination with the trapped heat induces knock, and elicits a response from a functional knock sensor.

A system for controlling propulsion of a marine vessel by a marine drive is provided, the marine drive having a marine engine that effectuates rotation of propulsor through a shift system that shifts amongst at least a forward gear position, a reverse gear position, and a neutral position. The system includes a remote control having a lever movable to provide a throttle demand input for controlling the marine engine and a shift demand input for controlling the shift system. A shift demand sensor measures a shift demand lever position to provide the shift demand input, and a throttle demand sensor measures a throttle demand lever positions to provide the throttle demand input. A control module is configured to detect shift demand sensor failure based on the shift demand lever position values and assign a predetermined throttle demand lever position as shift command position. When the throttle demand lever position reaches the shift command position, a shift command is generated instructing a change in gear position of the shift system.

Optimum fuel consumption and a stable combustion state are obtained by performing control to keep ignition always at an optimum timing such that ignition timing becomes MBT, without changing an EGR amount or an EGR rate that can realize the optimum fuel consumption rate. Therefore, in an internal combustion engine control device for controlling an internal combustion engine connected with a humidity sensor configured to detect humidity in an atmosphere and an ignition device configured to ignite an air-fuel mixture in a combustion chamber, the internal combustion engine control device includes a moisture amount calculation part configured to calculate an amount of moisture contained in intake air flowing into the combustion chamber according to a detection value of the humidity sensor; and an ignition timing control part configured to control ignition timing of the ignition device. In the internal combustion engine control device, the ignition timing control part controls the ignition timing of the ignition device so as to move in an advance direction as the amount of moisture in intake air calculated by the moisture amount calculation part increases.

An internal combustion engine comprises an exhaust purification catalyst arranged in an exhaust passage of the internal combustion engine; an upstream side air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas flowing into the exhaust purification catalyst; and a downstream side air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas flowing out from the exhaust purification catalyst. An abnormality diagnosis system of air-fuel ratio sensors judges that at least one of the air-fuel ratio sensors has become abnormal when a difference or ratio between an output value of said upstream side air-fuel ratio sensor and an output value of said downstream side air-fuel ratio sensor becomes outside a predetermined range of normal difference or predetermined range of normal ratio during atmospheric gas introduction control where the exhaust gas flowing into the exhaust purification catalyst becomes atmospheric gas.

A method and to a device for operating a pressure reservoir, where during a compression phase in a pump chamber, a pump periodically increases the pressure of a fluid located therein, and by means of a discharge valve controlled by differential pressure fluid under high pressure is allowed to be introduced from the pump chamber into the pressure reservoir. During a decompression phase following a compression phase, fluid from a fluid reservoir is introduced into the pump chamber by means of a controllable intake valve. In order to be able also to operate the pressure reservoir without a high pressure measurement directly in the pressure reservoir, the fluid pressure in the pressure reservoir is ascertained by means of a pressure determination in the pump chamber. The pressure determination takes place indirectly, monitoring of the intake valve in the decompression phase.

Methods and systems are provided for performing rationality check of a hydrocarbon sensor in an evaporative emission control system. In one example, a method may include sensing fuel vapors vented from a fuel vapor canister to atmosphere via the sensor, and performing sensor rationality check by flowing fuel vapors from a fuel tank to the fuel vapor canister via the sensor during loading of the fuel vapor canister.

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.