The purpose of the present invention is to detect deterioration of dead time characteristics of an air-fuel ratio sensor with high accuracy without causing running performance and exhaust performance to worsen. The present invention provides a control device for an engine, characterized by being equipped with: a means for detecting an air-fuel ratio; a means for changing the air-fuel ratio in a predetermined cycle; and a means for sending a notification of an abnormality in the air-fuel ratio detection means or causing at least a portion of the engine control to run in a fail-safe mode when the amplitude of an output signal of the air-fuel ratio detection means at a predetermined frequency is within a predetermined range and the required time or required angle to arrive at a predetermined value of the output signal of the air-fuel ratio detection means from a reference position or reference time point of an engine-related parameter is equal to a predetermined value or higher.

A control device for an exhaust gas sensor includes first means for estimating a temperature of a sensor element in accordance with impedance of a solid electrolyte, and second means for estimating the temperature of the sensor element in accordance with resistance of a heater. A first element temperature according to impedance of the sensor element in a predetermined detection timing is detected by the first means, and a second element temperature according to resistance of a heater of the sensor element in the predetermined detection timing is detected by the second means. The control device corrects the temperature of the sensor element that is estimated in accordance with heater resistance by the second means in accordance with a difference between the first element temperature and the second element temperature.

Systems and methods are described for controlling an aspirator control valve in an engine. An example method comprises closing the aspirator control valve responsive to diagnosing a first engine degradation condition and opening the aspirator control valve in response to diagnosing a second engine degradation condition.

Methods and systems are provided for leveraging the pressure dependency of an oxygen sensor for estimating an engine ambient pressure. An intake or exhaust oxygen sensor is used for ambient pressure estimation by applying a reference voltage to the sensor while the engine is being pulled-down in a hybrid vehicle, and correcting an output of the sensor for dilution effects due to ambient humidity. The estimated ambient pressure is used to correct or confirm pressure estimated by other sources, such as other pressure sensors or a pressure model, as well as to tune the performance of the engine.

The present description relates generally to methods and systems for detecting thermal aging and blackening in oxygen sensors. Thermal aging and blackening effects may be differentiated based on a monitored change in impedance in each of a pump cell and a Nernst cell of the oxygen sensor following application of an alternating voltage. In response to detection of thermal aging and/or blackening in the oxygen sensor corrective measures may be taken to ensure accurate oxygen estimation using the sensor.

An engine diagnostic tool includes a diagnostic engine calibration module structured to include a plurality of diagnostic processes for operating an internal combustion engine system of an immobilized vehicle. One or more of the plurality of diagnostic processes are structured to be an intrusive diagnostic process for the internal combustion engine system, wherein the intrusive diagnostic process causes the internal combustion engine system to operate outside of one or more calibration parameters. The diagnostic engine module is further structured to control the order and timing of each diagnostic process in the plurality of diagnostic processes.

The present invention relates to a control device and a control method for a variable valve timing mechanism that changes a valve timing by adjusting a rotational speed of a motor. The control device detects a phase angle RA1 based on an output of a crank angle sensor and an output of a cam angle sensor and calculates a change amount RA of a rotational phase based on a difference between a rotation amount of a sprocket and a rotation amount of the motor. The control device stops calculating change amount RA when a failure occurs in a motor rotation angle sensor. When a failure occurs in one of the crank angle sensor or the cam angle sensor, the control device stops calculating phase angle RA1 and calculates change amount RA using a normal one of the sensors and the motor rotation angle sensor.

An engine system and method for improving sampling of a port throttle pressure sensor. In one example, the port throttle pressure sensor is sampled a plurality of times during a cylinder cycle and different engine operating conditions are determined from selected samples. The system and method may improve engine air-fuel control as well as engine diagnostics.

An abnormality detection device for a humidity sensor has a humidity sensor disposed in an intake passage, a temperature sensor to detect an intake air temperature, and a controller. The controller is configured to detect a first sensor signal at a time of the intake air temperature being a first intake air temperature, and a second sensor signal at a time of the intake air temperature changing from the first intake air temperature and reaching a second intake air temperature, calculate values from which an influence of a temperature difference between the first and second intake air temperatures is excluded, from the first sensor signal and the second sensor signal, as respective humidity index values, and detect presence or absence of abnormality of the humidity sensor according to whether or not a deviation degree of these humidity index values is larger than a predetermined degree.

A method and a corresponding apparatus for carrying out a reference measurement on a sensor of an internal combustion engine of a motor vehicle during an overrun phase of the internal combustion engine, in order to detect measurement errors of the sensor. Provision is made that future overrun phases of the internal combustion engine, and the duration of the overrun phases, are predicted on the basis of route data; and that a reference measurement on the sensor is carried out only when the predicted duration of the overrun phase is long enough to carry out the reference measurement completely. With the method and apparatus presented, the functioning of sensors can be monitored during an overrun phase of a motor vehicle having an internal combustion engine.