Abstract: A control device for an internal combustion engine includes an electronic control unit that controls the air-fuel ratio of incoming exhaust gas flowing into a catalyst. The electronic control unit performs oxygen amount variation control in which a target air-fuel ratio for the incoming exhaust gas is switched between a rich set air-fuel ratio and a lean set air-fuel ratio. The electronic control unit switches the target air-fuel ratio to the rich set air-fuel ratio when an air-fuel ratio detected by an air-fuel ratio sensor is equal to or higher than a predetermined oxygen saturation determination air-fuel ratio. The oxygen saturation determination air-fuel ratio is leaner than an oxygen depletion determination air-fuel ratio and richer than the stoichiometric air-fuel ratio.

Abstract: Methods and systems are provided for a vehicle engine having a pre-chamber ignition system. In one example, a method may include adjusting one or more of an air injection amount and a fuel injection amount to a pre-chamber of an engine based on an air injection offset and a fuel injection offset learned while discontinuing fueling to cylinders of the engine and reducing air flow through the engine. In this way, air and fuel may be more accurately provided to the pre-chamber, thereby decreasing an occurrence of pre-chamber misfire.

Abstract: A post-treatment system includes two SCRs, a second SCR is connected to a booster in parallel, and a three-way valve is arranged before the second SCR and the booster, such that whether an exhaust gas flows through the second SCR or the booster is controlled by means of controlling the three-way valve. In the case of a low temperature, the three-way valve is controlled to close a branch of the booster, such that the exhaust gas flows through the second SCR and a first SCR that are connected in series, thereby reducing the energy loss caused by the exhaust gas flowing through the booster, and improving the NOx conversion efficiency in the case of a low temperature. In a case of a high temperature, the three-way valve is controlled to close a by-pass line, such that the exhaust gas flows through the booster and the first SCR.

Abstract: The invention relates to a control method that allows the mean quantity of nitrogen oxides per kilometer covered emitted by a vehicle fitted with an internal combustion engine associated with a post-treatment system to be kept below a predefined fixed threshold, for any journey made by the vehicle. The mean quantity emitted over a fixed elementary distance that has just been covered by the vehicle is calculated iteratively, together with a long-term conformity factor which is equal to the mean quantity emitted over the entire distance covered since the start of the journey. When it is found that the long-term conformity factor is above the threshold, the engine and/or the post-treatment system is regulated in such a way as to obtain, over the next fixed elementary distance, a mean quantity of nitrogen oxides per kilometer that is lower than the threshold value FC, for example equal to 90% of the threshold, whatever the engine operating point.

Abstract: The invention relates to a method for exhaust gas aftertreatment in an internal combustion engine. For purposes of the exhaust gas aftertreatment in the internal combustion engine, an exhaust gas system is provided in which a first three-way catalytic converter is arranged, as seen in the direction in which the exhaust gas of the internal combustion engine flows through the exhaust gas system, while at least another three-way catalytic converter is arranged downstream from the first three-way catalytic converter. Here, at least one lambda probe is arranged in an exhaust gas channel of the exhaust gas system upstream from the appertaining three-way catalytic converters. In the proposed method, a component temperature of the three-way catalytic converters is determined and compared to a light-OFF temperature.

Abstract: The present disclosure relates to a miniaturized fuel laboratory system that makes use of a housing, a processor housed within the housing, and a fuel inlet port supported from the housing for receiving a quantity of fuel to be used as a fuel test sample. The system may also have at least one fuel sensor housed in the housing in communication with the fuel inlet port for receiving the fuel test sample and carrying out combustion thereof. An electronic component may be housed in the housing, which enables communication with an external remote subsystem. A database may be incorporated which contains at least one of stored fuel characteristics or stored fuel analysis models, accessible by the processor. The processor may use fuel oxidation information generated by the fuel sensor, and at least one of the stored fuel characteristics or stored combustion models, to determine at least one fuel characteristic of the fuel test sample.

Abstract: The present invention relates to a heat pump system for a vehicle. The heat pump system includes a refrigerant-coolant heat exchanger for exchanging heat between refrigerant circulating through a refrigerant circulation line and coolant circulating through electronic units of the vehicle. The heat pump system can operate the heat pump mode even though outdoor air temperature is zero or lower or frosting is formed on the external heat exchanger because waste heat of the electronic units is retrieved through the refrigerant-coolant heat exchanger, thereby further enhancing heating performance and efficiency.

Abstract: A turbine housing includes an accommodation space that accommodates a turbine wheel, a discharge passage connected to the accommodation space, and a bypass passage that extends from the scroll passage bypassing the accommodation space and is connected to the discharge passage. The bypass passage extends so that an end surface on an upstream side of the catalytic device is located on a center axis of the bypass passage. An air-fuel ratio sensor is located closer to a center axis of the accommodation space than the center axis of the bypass passage. A protuberance that protrudes from an inner wall surface of the discharge passage is located between the accommodation space and the air-fuel ratio sensor. The protuberance protrudes toward the center axis of the accommodation space.

Abstract: A method of monitoring catalytic performance of a catalyst used in a reforming process, comprising a) collecting gaseous component data from the reforming process; b) calculating a gaseous component ratio from the gaseous component data; and c) utilizing the gaseous component ratio to estimate an amount of catalytic activity remaining in the catalyst used in the reforming process, a number of days on stream remaining for the catalyst used in the reforming process, or both.

Abstract: A control apparatus comprising an air-fuel ratio sensor disposed between the exhaust gas aggregated portion and the three-way catalyst, and which outputs an output value corresponding to an amount of oxygen and an amount of unburnt substances that has reached the exhaust-gas-side electrode layer via the porous; an actual detected air-fuel ratio obtaining section which obtains an actual detected air-fuel ratio by converting an actual output value of the air-fuel ratio sensor into an air-fuel ratio; and an instructed fuel injection amount calculation section which corrects the amount of the fuel injected from a plurality of the fuel injection valves so that the actual detected air-fuel ratio coincides with a target air-fuel ratio; and an air-fuel ratio imbalance indicating value obtaining section which obtains an air-fuel ratio imbalance indicating value which becomes larger as a degree of a non-uniformity among a plurality of the cylinders of cylinder-by-cylinder air-fuel ratios.

Abstract: In a limited-current type gas sensor which detects oxygen-containing gas contained in an exhaust gas of an internal combustion engine, the decomposition current value of water (H2O) may be detected, and existence of an abnormality of output characteristics of the sensor may be diagnosed based on its deviation from a reference decomposition current value of water corresponding to the concentration of water contained in the exhaust gas. A NOx sensor and a SOx sensor can also diagnose remarkable and minute abnormalities of output characteristics. In addition, the reference decomposition current value of water may be acquired based on the concentration of water detected by a separate humidity sensor or the decomposition current value of oxygen detected by the limited-current type gas sensor. The reference decomposition current value of water may be corrected based on a decomposition current value of oxygen detected during a fuel cut.

Abstract: A method for controlling operation of an internal combustion engine determines an estimated NOx value as a function of at least one engine operating parameter. The method also determines an actual NOx value using a NOx sensor positioned in an exhaust gas stream of the internal combustion engine. The method detects at least one condition indicative of whether or not the actual NOx value is accurate. The actual NOx value is used for controlling engine operation when the at least one condition indicates that the actual NOx value is accurate, while the estimated NOx value is used for controlling engine operation when the at least one condition indicates that the actual NOx value is inaccurate.

Abstract: A control apparatus for an internal combustion engine is provided. The control apparatus includes an electronic control unit. The electronic control unit is configured to: set a target air-fuel ratio at a lean air-fuel ratio that is leaner than a theoretical air-fuel ratio from time at which an output air-fuel ratio of a downstream-side air-fuel ratio sensor becomes equal to or lower than a rich determination air-fuel ratio; and set the target air-fuel ratio at a rich air-fuel ratio that is richer than the theoretical air-fuel ratio after an oxygen storage amount of the exhaust gas control catalyst becomes equal to or larger than the specified switching reference storage amount and the output air-fuel ratio of the downstream-side air-fuel ratio sensor becomes higher than the rich determination air-fuel ratio.

Abstract: One example includes a sensor for sensing NOx, including an electrically insulating substrate, a first electrode and a second electrode, each disposed onto the substrate, wherein each of the first electrode and the second electrode has a first end configured to receive a current and a second end and a sensor element formed of nickel oxide powder, the sensor element disposed on the substrate in electrical communication with the second ends of the first electrode and the second electrode. In some examples, electronics are used to measure the change in electrical resistance of a sensor in association with NOx concentration near the sensor. In some examples, the sensor is maintained at 575° C.

Abstract: Methods and systems are provided for estimating an amount of exhaust gas recirculation (EGR) from an exhaust passage into an intake passage of an engine system by operating an exhaust oxygen sensor in a variable voltage (VVs) mode. In one example, a method includes during operation of an exhaust oxygen sensor in the VVs mode where a reference voltage of the exhaust oxygen sensor is adjusted from a lower, first voltage to a higher, second voltage, adjusting engine operation based on the EGR amount estimated based on an output of the exhaust oxygen sensor and a learned correction factor based on the second voltage. In this way, the exhaust oxygen sensor may be used to correct for variations arising due to changing fuel composition and ambient humidity and further used to estimate the amount of EGR being recirculated in the system, thereby enhancing engine fueling and EGR control.

Abstract: A method is described for compensating for a voltage offset in a voltage-lambda characteristic curve of a two-point lambda sensor in relation to a reference voltage-lambda characteristic curve of the two-point lambda sensor, the two-point lambda sensor being situated in an exhaust duct of an internal combustion engine. It is provided that the slope of the voltage-lambda characteristic curve is determined for an output voltage of the two-point lambda sensor and is compared to the slope of a reference voltage-lambda characteristic curve at equal output voltage, and the voltage offset is determined from a deviation of the determined slope of the voltage-lambda characteristic curve from the slope of the reference voltage-lambda characteristic curve. Also described is a control unit for carrying out the method. The method and the control unit enable the determination of and compensation for a voltage offset of a two-point lambda sensor caused by aging or manufacturing tolerances.

Abstract: A control device for an internal combustion engine includes first and second intake ports (16a, 16b) independent of each other, and first and second fuel injection valves (30a, 30b) provided for the first and second intake ports (16a, 16b), respectively, in each cylinder. Under a situation where an exhaust variable valve mechanism (38) is controlled such that a first exhaust valve (32a) is opened earlier than a second exhaust valve (32b), first and second air-fuel ratios A/F1, A/F2 are respectively obtained in a first half and a second half of an exhaust stroke. When the obtained first air-fuel ratio A/F1 (or the second air-fuel ratio A/F2) is lean, a fuel injection amount in a next cycle by the first or second fuel injection valve (30a, 30b) corresponding to the first air-fuel ratio A/F1 (or the second air-fuel ratio A/F2) that is lean is reduced.

Abstract: A first parameter correlated with a degree of a variation in the output from the air-fuel ratio sensor is calculated. A possible range of a second parameter representing a degree of a variation in air-fuel ratio among the cylinders is determined based on the first parameter. The first parameter is calculated with an air-fuel ratio of a predetermined cylinder forcibly changed. A difference between the unchanged first parameter and the forcibly changed first parameter is determined. A first characteristic representing a relation between the second parameter and the difference is determined based on the possible range of the second parameter and the difference. One of the determination value and the first parameter calculated before the forced change is corrected based on inclination of the determined first characteristic.

Abstract: A gas sensor includes a sensor housing and a sensing element located within the sensor housing. The sensing element has a distal end and defines an axis. The gas sensor also includes a sensor protection device coupled to the sensor housing and at least partially surrounding the distal end of the sensing element. The sensor protection device includes a first member coupled to the housing, the first member having a generally rectangular cross-sectional shape in a plane perpendicular to the axis. The first member includes a gas inlet and a gas outlet. The sensor protection device also includes a second member coupled to the housing.

Abstract: Methods and systems are provided for estimating water storage in a charge air cooler (CAC). In one example, an amount of water in charge air exiting the CAC may be based on an output of an oxygen sensor positioned downstream of the CAC. Further, engine actuators may be adjusted to increase combustion stability and/or reduce condensate formation based on the amount of water exiting the CAC.

Abstract: Methods and systems are provided for accurately learning the zero point of an intake gas oxygen sensor in varying ambient humidity conditions. The learned zero point is corrected based on an estimated ambient humidity to calibrate the reading for dry air conditions or standard humidity conditions. EGR control is performed by comparing the output of an intake oxygen sensor during EGR conditions relative to the humidity-corrected zero point.

Abstract: Methods and systems are provided for estimating a PCV flow to an engine based on the output of an exhaust gas oxygen sensor. During DFSO conditions, a reference voltage of the sensor is modulated initially with an intake throttle open and then with the intake throttle closed. PCV flow leaking past the piston valves in an aging engine, as well as an ambient humidity estimate, are inferred based on the outputs of the sensor during the modulating with the intake throttle open and closed.

Abstract: Various methods and system are described for determining ambient humidity via an exhaust gas sensor disposed in an exhaust system of a variable displacement engine. A reference voltage of a sensor coupled to an inactive engine bank is modulated between a first and second voltage to estimate ambient humidity. Concurrently, a reference voltage of a sensor coupled to an active engine bank is modulated between the first and second voltage, or at the first voltage, to estimate fuel alcohol content, or exhaust air-fuel ratio, respectively.

Abstract: The present invention intends to perform control for detecting a change in air-fuel ratio with high accuracy by an exhaust gas sensor in an internal combustion engine having a turbocharger with a wastegate valve. A control apparatus for an internal combustion engine according to the present invention includes: a turbocharger; a wastegate through which an exhaust gas passes while bypassing a turbine; a wastegate valve for opening/closing the wastegate; an exhaust gas sensor provided in an exhaust passage on the downstream side from the turbine and the wastegate valve; and air-fuel ratio change detection controlling means for executing air-fuel ratio change detection control to change an air-fuel ratio on the upstream side from the turbine and the wastegate valve and detect a change in the air-fuel ratio by the exhaust gas sensor.

Abstract: The invention relates to a method and to a regulating device for regulating an air-fuel ratio of an internal combustion engine (10), wherein an exhaust-gas composition of an exhaust gas of the internal combustion engine (10) is determined by virtue of an actual probe signal, which is dependent on the exhaust-gas composition, being detected by means of an exhaust-gas probe (22) and the exhaust-gas composition being determined as a function of the actual probe signal by means of a characteristic curve or a calculation rule, and wherein the determined exhaust-gas composition is compared with a setpoint value or a threshold value, the attainment or exceedance of which triggers a manipulation of the air-fuel ratio supplied to the internal combustion engine (10), wherein, in order to take into consideration at least one disturbance variable which affects the actual probe signal, a safety margin (?S) is defined which is applied to the characteristic curve or calculation rule, to the actual probe signal or to the set

Abstract: A method of monitoring an exhaust gas sensor coupled in an engine exhaust is provided. The method comprises indicating exhaust gas sensor degradation based on a difference between a first set of estimated parameters of a rich operation model and a second set of estimated parameters of a lean operation model, the estimated parameters based on commanded lambda and determined lambda values collected during selected operating conditions. In this way, sensor degradation may be indicated with data collected in a non-intrusive manner.

Abstract: When an engine is in a predetermined steady operating state, a gradient accumulation average value ?Aulsa corresponding to the amount of change in the air-fuel ratio AF, detected by an air-fuel ratio sensor, over the period of time from when an upper peak is reached, at which the direction of change in the air-fuel ratio AF is inverted to when a lower peak is reached, at which the subsequent inversion of the direction occurs, is calculated (S100 to S160) and, when the calculated gradient accumulation average value ?Aulsa is greater than a predetermined threshold value ?Aref1 that is determined in advance as an upper limit (absolute value) of the range, in which it may be determined that the air-fuel ratio is even between the cylinders of the engine (S165 to S175), it is determined that the engine is in an air-fuel ratio imbalance state, in which there is an imbalance in air-fuel ratio between the cylinders of the engine.

Abstract: Method for estimating NOx creation in a combustion process of an engine including a variable volume combustion chamber includes monitoring engine sensor inputs including a cylinder pressure within the combustion chamber. A mass fraction burn value for combustion can be modeled within the combustion chamber based upon said sensor inputs, wherein said mass fraction burn value indexes a crank angle at which a selected percentage of injected fuel is burned in a combustion cycle. The state of combustion within the combustion chamber can be estimated based upon the mass fraction burn value, the state of combustion including a combustion phasing and a combustion strength. NOx creation within the combustion chamber can be estimated with a non-linear function based upon said state of combustion.

Abstract: A judging device comprises a catalyst, an upstream air/fuel ratio sensor having an air/fuel ratio sensing element covered with a diffusion resistance layer, and a downstream air/fuel ratio sensor. The judging device performs main feedback control to equalize the air/fuel ratio indicated by the output value of the upstream air/fuel ratio sensor to an upstream target air/fuel ratio and sub-feedback control to equalize the output value of the downstream air/fuel ratio sensor to a downstream target value. The judging device acquires “an imbalance judging parameter” which increases with “the increase of the difference between the amount of hydrogen contained in the exhaust gas before the exhaust gas passes through the catalyst and that after the exhaust gas passes through the catalyst” according to the sub-feedback amount. When the imbalance judging parameter is larger than an abnormality judgment threshold, the judging device judges that an air/fuel ratio imbalance among the cylinders has occurred.

Abstract: Methods and systems for an engine system including an exhaust gas sensor are disclosed. In one example, under a first engine fueling condition, an air-fuel ratio correction factor is determined based on an expected air-fuel ratio and an actual air-fuel ratio. During a second engine fueling condition and a third engine non-fueling condition, fuel alcohol content and ambient humidity, respectively, are determined based on the exhaust gas sensor and corrected based on the air-fuel ratio correction factor.

Abstract: Active control of one or more exhaust gas recirculation loops is provided to manage and EGR fraction in the charge flow to produce desired operating conditions and/or provide diagnostics in response to at least one of an oxygen concentration and a NOx concentration in the charge flow and in the exhaust flow.

Abstract: A fuel injection amount control system acquires a pre-correction air-fuel ratio imbalance index value that increases as the degree of ununiformity in the air-fuel ratio among cylinders increases, based on an output value of an upstream air-fuel ratio sensor, and obtains a value (intake air amount correlation value) corresponding to the intake air amount and a value (engine speed correlation value) corresponding to the engine speed over a period in which the pre-correction air-fuel ratio imbalance index value is acquired. Also, a post-correction air-fuel ratio imbalance index value is acquired by correcting the pre-correction air-fuel ratio imbalance index value based on the intake air amount correlation value and the engine speed correlation value, and the air-fuel ratio of the engine is controlled based on the post-correction air-fuel ratio imbalance index value.

Abstract: A system and method for sampling fluid from a top land piston crevice of a reciprocating piston engine. Access into the crevice is via a length of tubing inserted into a bore through the piston wall. Two valves, first a relief valve and then a piloted check valve, operate together to capture a sample of fluid from the crevice at a time just before TDC of the piston on its compression stroke. The sampled fluid flows from the check valve into a sample container. The valves further cooperate to close fluid communication from the crevice after a sample is taken, which allows the engine to operate normally.

Abstract: A method for measuring and/or calibrating a gas sensor for determining oxygenic gas components in gas mixtures in exhaust gases of internal combustion engines. The gas sensor has one internal pump electrode IPE, one external pump electrode APE and one decomposition electrode NOE. The measurement and/or calibration may be carried out during the ongoing operation of the gas sensor by removing the gas component and/or oxygen from one of the chambers, by introducing oxygen in a controlled manner into one of the chambers with the aid of electrochemical pumping processes. The changes caused by the introduced oxygen are measured against an additional electrode and the gas sensor may be measured and/or calibrated using the measured values.

Abstract: Methods and systems for an engine system including an exhaust gas sensor are disclosed. In one example, under a first engine fueling condition, an air-fuel ratio correction factor is determined based on an expected air-fuel ratio and an actual air-fuel ratio. During a second engine fueling condition and a third engine non-fueling condition, fuel alcohol content and ambient humidity, respectively, are determined based on the exhaust gas sensor and corrected based on the air-fuel ratio correction factor.

Abstract: Various systems and methods are described for an exhaust gas sensor coupled to an exhaust system of an engine. One example method comprises, during selected engine fueling conditions, alternating between applying first and second voltages to the sensor; and identifying an amount of alcohol in fuel injected to the engine based on sensor outputs at the first and second voltages.

Abstract: Various systems and methods are described for an exhaust gas sensor coupled to an exhaust system of an engine. One example method comprises, during selected engine fueling conditions, alternating between applying different voltages to the sensor; and identifying an amount of alcohol in fuel injected to the engine based on sensor outputs at the different voltages.

Abstract: A diagnostic system for a vehicle includes an error module, an equivalence ratio (EQR) module, a threshold determination module, and a fault indication module. The error module determines an error value based on a difference between an amount of oxygen in exhaust measured by an exhaust gas oxygen sensor (EGO) upstream of a catalyst and an expected value of the amount. The EQR module selectively controls fuel injection based on the error value. The threshold determination module determines an error threshold based on a flow rate of fuel vapor from a vapor canister to an intake manifold of an engine. The fault indication module selectively indicates that a fault is present in the EGO sensor based on the error value and the error threshold.

Abstract: A control system for a turbo charged natural gas engine. A butterfly valve used for fuel control upstream of a carburetor provides non-linear flow response during opening and closing and a flow compensator compensates for the non-linear response. A throttle valve position sensor acts in association with a controller which compares the throttle valve position signal with a predetermined set point and thereby opens or closes the waste gate of the turbo charger which affects oxygen content in the exhaust. A compensator for a throttle valve used with electronic engine controllers is also provided.

Abstract: A gas sensor including a gas sensor element that extends in an axial direction and has a detection section at a front-end side thereof, and an electrode pad at a rear-end side thereof; a connection terminal that is electrically connected to the electrode pad; and an insulated separator that extends along the axial direction and has an inserting hole into which the connection terminal is inserted. An element side section is arranged within the inserting hole and is connected the electrode pad, and an external circuit side section extends further to the outside in a diametrical direction than an outer surface of the separator through one or more first bending sections from the element side section.

Abstract: The fact that “with respect to a process in which the output value of a downstream air-fuel ratio sensor (sensor output value) is inverted from the minimum output value to the maximum output value during execution of an active control, the local maximum and minimum values of the secondary differential value of the sensor output value is widely affected by the size of the response delay of the downstream air-fuel ratio sensor and the size of the degree of the degradation of the three-way catalyst” is utilized. By preliminarily acquiring and memorizing, as maps, these relations obtained through an experiment, and applying the “local maximum and minimum values of the secondary differential value of the sensor output value” calculated from the transition of the sensor output value acquired during execution of the active control to the maps, the response delay (time constant) of the downstream air-fuel ratio sensor is acquired.

Abstract: Methods systems and device for detecting humidity in air through use of an ammonia sensor included in the exhaust of an engine, such as a diesel engine are provided. In one example, a method for an engine having an exhaust with an ammonia sensor includes adjusting an operating parameter in response to ambient humidity, the ambient humidity based on a first ammonia sensor reading at a first exhaust air-fuel-ratio and a second ammonia sensor reading at a second exhaust air-fuel-ratio.

Abstract: Various systems and methods are described for an exhaust gas sensor coupled to an exhaust system of an engine. One example method comprises, during selected engine fueling conditions, alternating between applying first and second voltages to the sensor; and identifying an amount of alcohol in fuel injected to the engine based on sensor outputs at the first and second voltages.

Abstract: A sensor control apparatus (3) includes a full-range gas sensor composed of an oxygen concentration detection cell having a pair of electrodes (21, 22) and an oxygen pump cell having a pair of electrodes (19, 20). In an electric circuit section (30), an Ip current flowing between the electrodes (19, 20) is controlled such that an electromotive force Vs produced between the electrodes (21, 22) becomes equal to a reference voltage. The reference voltage is usually set to a first reference voltage. However, when the subject gas is air, the reference voltage is set to a second reference voltage. Humidity of the subject gas is detected on the basis of an error ?Ip between an Ip current detected when the reference voltage is set to the first reference voltage, and an Ip current detected when the reference voltage is set to the second reference voltage.

Abstract: An oxygen concentration sensor is disposed in an engine exhaust passageway. The alcohol concentration in the fuel used in the internal combustion engine is detected. A target impedance is set on the basis of the detected alcohol concentration. The actual impedance of a sensor element of the oxygen concentration sensor is detected. The heater output of the exhaust gas sensor is controlled so that the actual impedance becomes equal to the target impedance, whereby the temperature of the sensor element represented by the impedance becomes equal to a target temperature represented by the target impedance.

Abstract: Embodiments for estimating intake air humidity in an engine are provided. In one example, an engine method comprises adjusting an engine parameter in response to intake air humidity estimated based on a concentration of one or more engine-out emissions. In this way, one or more exhaust emission sensors may be used to estimate intake air humidity.

Abstract: Provided is a control apparatus, which can successfully suppress that deterioration of combustion is caused in response to inflow of a large amount of blow-by gas to cylinders at the time of a valve return from a valve stop state in an internal combustion engine including a positive crankcase ventilation system and a variable valve operating mechanism that is capable of stopping at least one valve of an intake valve and exhaust valve in a closed state. A valve stop control is performed which stops the intake valve and exhaust valve in a closed state when a fuel cut of the internal combustion engine is executed. A deviation amount ?A/F between a predetermined target air fuel ratio and an actual air fuel ratio detected by an A/F sensor at the time of a valve return is obtained. A correction is performed to decrease a fuel injection amount by a fuel amount equivalent to the deviation amount ?A/F at the time of the subsequent valve returns.

Abstract: Various systems and methods are described for an exhaust gas sensor coupled to an exhaust system of an engine. One example method comprises, during selected engine fueling conditions, alternating between applying first and second voltages to the sensor; and identifying an amount of alcohol in fuel injected to the engine based on sensor outputs at the first and second voltages.

Abstract: A system and method for controlling engine operation includes a timer module that determines a time period from when a catalyst light-off mode is entered to when an oxygen sensor signal reaches an oxygen sensor threshold and a comparison module that generates an error signal and determines when the time period is above a time threshold.

Abstract: A system for compensating for changes in behavior of an oxygen sensor. In one embodiment, the system includes an oxygen sensor configured to produce an output indicative of an oxygen level in an exhaust stream produced by an internal combustion engine. An electronic control unit receives the output of the oxygen sensor and is configured to cause the internal combustion engine to operate in an overrun mode. The electronic control unit is programmed or otherwise configured to determine whether a change in oxygen level over time is approximately zero. When the change in oxygen level is approximately zero or near zero, the electronic control unit determines a compensation factor for the oxygen sensor.