An engine bank-to-bank airflow balancing technique includes calculating current and offset volumetric efficiencies of the engine and calculating a slope representing (i) a difference between the offset and current volumetric efficiencies and (ii) a difference between offset and current intake camshaft positions. Based on the respective exhaust gas oxygen concentrations, the technique involves calculating a volumetric efficiency correction corresponding to each cylinder bank and based on the slope and the volumetric efficiency corrections, calculating target intake camshaft position shifts. The technique further involves controlling offsets of the intake camshafts based on the target intake camshaft position shifts. After a predetermined number of target intake camshaft position shifts are determined and stored with respect to various combinations of engine speed and a ratio of intake manifold pressure to barometric pressure, final intake camshaft position shifts may be determined and utilized when determining the intake camshaft positions.

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.

An engine unit, including: a plurality of cylinders respectively cooperating with a plurality of pistons; a plurality of individual exhaust pipes configured to allow exhaust gases from the plurality of cylinders to respectively flow therethrough; an exhaust manifold, including a merge portion into which the individual exhaust pipes merge, and a catalyst disposed downstream thereof; a group of pre-catalyst oxygen sensors disposed between the cylinders and the catalyst for all paths of the exhaust gases flowing into the catalyst from the plurality of cylinders; a post-catalyst oxygen sensor disposed in the exhaust manifold, downstream of the catalyst in the flow direction of the exhaust gas; and a control device configured to detect a cylinder-to-cylinder imbalance in air-fuel ratio between the plurality of cylinders, and a deterioration of the catalyst, using detection results of pre-catalyst and post-catalyst oxygen sensors without using an air-fuel ratio sensor.

An engine unit, including: a plurality of cylinders respectively cooperating with a plurality of pistons; a plurality of individual exhaust pipes configured to allow exhaust gases from the plurality of cylinders to respectively flow therethrough; an exhaust manifold, including a merge portion into which the individual exhaust pipes merge, and a catalyst disposed downstream thereof; a group of pre-catalyst oxygen sensors disposed between the cylinders and the catalyst for all paths of the exhaust gases flowing into the catalyst from the plurality of cylinders; a post-catalyst oxygen sensor disposed in the exhaust manifold, downstream of the catalyst in the flow direction of the exhaust gas; and a control device configured to detect a cylinder-to-cylinder imbalance in air-fuel ratio between the plurality of cylinders, and a deterioration of the catalyst, using detection results of pre-catalyst and post-catalyst oxygen sensors without using an air-fuel ratio sensor.

Systems and methods for controlling fuel that is supplied to cylinders of an internal combustion engine are described. In one example, the fuel is controlled in response to output of two different outer-loop fuel controllers. The fuel may be controlled according to the individual separate outputs of outer-loop controllers or the combined outputs of the two different fuel controllers.

Systems and methods for controlling fuel that is supplied to cylinders of an internal combustion engine are described. In one example, oxygen sensors are placed in an exhaust system of an engine such that each oxygen sensor may detect exhaust gas from a pair of engine cylinders. The oxygen sensors may then provide feedback to coupled and decoupled fuel controllers.

Systems and methods for controlling fuel that is supplied to cylinders of an internal combustion engine are described. In one example, oxygen sensors are placed in an exhaust system of an engine such that each oxygen sensor may detect exhaust gas from a pair of engine cylinders. The oxygen sensors may then provide feedback to coupled and decoupled fuel controllers.