An exhaust sensor 1 comprises a sensor cell 51, a voltage application circuit 61, a current detection circuit 62 and a concentration calculating part 80a. The current detection circuit detects a first current flowing through the sensor cell when fuel cut control is being performed in the internal combustion engine and a predetermined voltage is applied from the voltage application circuit to the sensor cell, and detect a second current flowing through the sensor cell when normal control is being performed in the internal combustion engine and the predetermined voltage is applied from the voltage application circuit to the sensor cell. The concentration calculating part is configured to calculate the concentration higher with respect to the second current when the first current is relatively low compared with when the first current is relatively high.

A device is provided, which makes it possible to perform a failure diagnostics for a filter more accurately even in the case of an internal combustion engine which is constructed to be capable of using both of gaseous fuel and liquid fuel. The device of the invention comprises judging means which judges any failure of the filter by comparing the added-up amount of the particulate matter contained in the exhaust gas as detected by a PM amount detecting sensor during a predetermined period and the added-up amount of the particulate matter contained in the exhaust gas as estimated by PM amount estimating means during the predetermined period, wherein the PM amount estimating means estimates the added-up amount of the particulate matter contained in the exhaust gas on the basis of the predetermined parameter and only a fuel injection amount of the liquid fuel out of a fuel injection amount of the gaseous fuel and the fuel injection amount of the liquid fuel.

A short-circuit pinpointing device for testing a wide-range air/fuel sensor includes a current-sink and a controller. The current-sink is selectively connectable to one or more of sensor-terminals of a wide-range air/fuel sensor that include a reference-terminal, a pump-terminal, a return-terminal, and a tag-terminal. The controller is in communication with the current-sink and the sensor-terminals. The controller controls the connection of the current-sink to the one or more sensor-terminals. The controller also determines one or more status-values based on signals present at the sensor-terminals. The controller also determines a sensor-status of the wide-range air/fuel sensor based on the connection of the current-sink and the one or more status-values.

In a method for dynamic monitoring of gas sensors of an internal combustion engine, in the event of a change of the gas state variable to be measured, a dynamic diagnosis is carried out based on a comparison of a measured signal which is an actual value of an output signal of the gas sensor and a modeled signal which is a model value. The output signal of the gas sensor is filtered using a high-pass filter and higher-frequency signal components are analyzed.

A hydrocarbon sensor diagnosis system includes a computer programmed to collect data from a hydrocarbon sensor while an exhaust gas recirculation system is in an open state. The hydrocarbon sensor is mounted along an engine air intake between an exhaust port of the exhaust gas recirculation system and an intake port of a cylinder head. The computer is further programmed to determine whether a hydrocarbon sensor fault exists based at least on the collected data.

The invention relates to a control method for controlling a fuel injection system (10) of an internal combustion engine, wherein, wherein, in a fault situation of the fuel injection system (10), a camshaft angle of a camshaft (34) which drives a pump piston (32) of a high-pressure fuel pump (14) of the fuel injection system (10) is adjusted such that an injection time (tI) of injector valve (42) which injects the fuel from the fuel injection system (10) into a combustion chamber of the internal combustion engine lies in a pressure trough (50) of a pressure oscillation in a high-pressure region (16).

Methods and systems are provided for diagnosing sensors in an engine intake by utilizing in an evaporative leak check module pump (ELCM pump). In one example, during engine off conditions, the ELCM pump in an evaporative emission system of the vehicle may be operated in a pressure mode to flow ambient air from the evaporative emissions system to the intake manifold. During humidity sensor diagnostics, the air flow may be used to generate water vapors within the intake manifold, and humidity sensor may be rationalized by monitoring an output of the humidity sensor; and during MAF sensor diagnostics, MAF sensor may be rationalized by monitoring if the MAF sensor output corresponds to a flow rate generated by the ELCM.

An estimation unit calculates an estimated value of oxygen concentration in an exhaust passage on the basis of a target injection amount of a fuel injection valve and an air intake amount of an engine. A first determination unit determines the relationship of a detected value to the estimated value of the oxygen concentration, in both a fuel-injecting state and a non-fuel-injecting state. For each of a plurality of cylinders, a second determination unit acquires crankshaft angular acceleration during the expansion strokes of the cylinders in the fuel-injecting state, and determines the relationship of each angular acceleration to the average value of all of the angular accelerations. An abnormality determination unit determines whether or not there is an abnormality in an engine system on the basis of the determination results of the first and second determination units.

The present teaching aims to provide: a cam angle sensor fault diagnosis apparatus for straddled vehicle, capable of detecting a fault of a cam angle sensor installed in a straddled vehicle and guessing a fault place; an engine system; and a straddled vehicle. A cam angle sensor fault diagnosis apparatus for straddled vehicle includes: a cam signal receiving unit connected to a signal output line through which a cam angle sensor outputs a cam signal in accordance with the rotation angle, the cam signal receiving unit being configured to receive a cam signal via the signal output line; a state determination unit that determines one or two fault states of the cam angle sensor from a disconnection state, a power supply fault state, and a ground fault state, distinguishably from the other fault states, in accordance with a signal level of a cam signal received by the cam signal receiving unit; and a signal output unit that outputs a fault signal representing the one or two fault states determined by the state determination unit, in such a manner that the fault signal representing the one or two fault states is different from a fault signal representing the other fault states.

In an air handling system of an opposed-piston engine, mass airflow sensor operation is monitored by comparing mass airflow measured by the sensor with mass airflow through a supercharger.