Methods and systems are described for an engine with a cam torque actuated variable cam timing phaser. Phaser positioning control is improved by reducing inaccuracies resulting from inadvertent spool valve and/or phaser movement when the spool valve is commanded between regions. In addition, improved spool valve mapping is used to render phaser commands more consistent and robust.

Methods and systems are provided for enabling a transfer function of a direct injector and a port injector, each fueling an engine cylinder, to be accurately learned. During selected conditions, the direct injected fuel fraction may be actively changed from a target fraction to one of an upper and lower limit of the direct injector so as to provide a measurable air-fuel ratio error. Fueling errors for the distinct fuel injectors is then learned based on the measured air-fuel ratio error relative to the actively changed fuel fraction.

The invention relates to a method for checking a functionality of a differential pressure measuring unit (31) in an exhaust gas recirculation system (1) of a motor vehicle, and a corresponding exhaust gas recirculation system (1). In an air intake duct (5), a sensor flap (11) is provided downstream of an air filter (9) and upstream of an opening (37) of an exhaust gas recirculation duct (25). This sensor flap (11) is set in two different positions and a value of a pressure drop in the exhaust gas stream is measured for each position as said gas stream flows through an exhaust gas recirculation stream valve (29) provided in the exhaust gas recirculation duct (25). If the measured pressure drop does not significantly change despite the movement of the sensor flap (11), it can be assumed that there is a fault in the differential pressure measuring unit (31). In particular, it is possible to detect when a hose (41), which connects a differential pressure sensor of the differential pressure measuring unit (31) to a connector (35) on the exhaust gas recirculation duct (25) downstream of the exhaust gas recirculation stream valve (29) has torn, slipped off or become blocked.

A method for predicting failure in a cylinder of a multi-cylinder engine is provided. Each cylinder has an associated pressure sensor to provide a signal indicative of pressure in the cylinder. The method includes identifying whether there is a non-fueling interval associated with any of the cylinder on the engine. The method includes determining at least one of parameters such as an indicated mean effective pressure, a peak cylinder pressure, a total heat released, or a total duration of heat released over a combustion cycle for the cylinder. The method includes comparing the at least one of the parameters with predefined threshold value, determining whether any of the parameters exceeds the predefined threshold value, and generating a signal indicating the impending cylinder failure if at least one of the parameters exceeds the corresponding predefined threshold value.

A method for operating an internal combustion engine with a motor having a number of cylinders and an injection system having a common rail with a number of injectors assigned to the cylinders and similar high pressure components, which is designed to hold fuel from the common rail for the injector, wherein the method has the steps: injecting fuel from the common rail into a cylinder by way of an injector, determining a fuel pressure for a high-pressure component, in particular the common rail, the injector and/or the individual reservoir, having at least one high-pressure sensor measuring the fuel pressure. Provision is made for a defect in the high-pressure sensor to be detected in that a check is made as to whether magnitude of the high-pressure control deviation (ep) during a predetermined time interval (t.sub.Limit1.sup.SD, t.sub.Limit2.sup.SD, t.sub.Limit3.sup.SD) exceeds a predetermined limiting value (e.sub.Limit1.sup.SD, e.sub.Limit2.sup.SD, e.sub.Limit3.sup.SD).

A control apparatus is provided for controlling an exhaust gas sensor. The exhaust gas sensor includes a first cell, a second cell configured to output electric current depending on the concentration of a measurement target component in exhaust gas from which oxygen has been removed by the first cell, and a heater configured to heat the first and second cells. The control apparatus includes a heater controlling unit, a current detecting unit configured to detect the electric current outputted from the second cell, and a deterioration determining unit. The deterioration determining unit causes the heater controlling unit to change output of the heater and thereby changes the temperature of the first cell. During the change in the output of the heater, the deterioration determining unit determines, based on an amount of change in the electric current detected by the current detecting unit, whether or not the second cell is deteriorated.

Various embodiments may include a method for operating an internal combustion engine having a wastegate turbocharger comprising: measuring an intake pipe pressure; determining a cylinder air mass from the pressure; injecting an amount of fuel into a cylinder of the internal combustion engine based on the air mass; determining and a plausible intake pipe pressure gradient for a current engine operating point; calculating a gradient of the measured intake pipe pressure during a full-load acceleration; comparing the stored plausible intake pipe pressure gradient to the calculated gradient; identifying manipulation of the intake pipe pressure sensor if the difference between the stored plausible intake pipe pressure gradient and the calculated gradient exceeds a selected threshold value; and limiting a power output of the engine if manipulation is identified.

A method and test device for recognizing detecting whether a mass air flow meter of intake air of an internal combustion engine is defective is provided. In the method and device, a test procedure is executed using a pilot controller while a mixture controller that is used in non-test engine operation is deactivated. The pilot controller for the mixture of fuel and air in the respective cylinders outputs control values which, during normal operation of the internal combustion engine via the mixture control, are varied on the basis of a mixture deviation of the current mixture from a stoichiometric mixture. The engine is set to one or more different idling speeds and at each respective idling speed the mixture deviation is detected. If the detected mixture deviation(s) (i'lA.) satisfy a predetermined criteria thresholds, the air flow meter is identified as defective.

A method and apparatus for field testing an NO.sub.x-sensor in a diesel engine exhaust system are disclosed. The apparatus is connectable to a truck having a lean burn diesel type engine, via an on-board diagnostic connector. A test cycle is performed on a running engine in at least two different states of operation, while NO.sub.x related values issued by the at least one NO.sub.x-sensor are measured over a predefined period of time. One state of operation is obtained by simultaneously opening the exhaust gas recirculation valve and controlling the back pressure valve for increasing backpressure. A dedicated algorithm is used to compare the measured values to a predefined model, and to provide a numerical summary and statistical evaluation of the sensor functioning.

An engine diagnostic system includes a control system having a controller operatively connected to an engine. A monitoring system has a sensor operatively connected to the engine. A diagnostic system is operatively connected to the engine. The diagnostic system is configured to implement a sensor diagnostic procedure that includes a sensor health test. The sensor health test includes comparing a measured value of a sensor to an expected value and determining the health of the sensor based on the difference between the measured value and the expected value. The sensor diagnostic procedure can also include telematics data analysis.