Robert Boschgmbh

Heiko Oertel

Michael Lehner

Andrea Lohmann

Klaus Ries-Mueller

Peter Wiltsch

Juergen Schwabe

Heinz Viel

Uwe Buck

Ralf Schnee

The invention relates to a method for detecting combustion misfires in multi-cylinder internal combustion engines having several simultaneously igniting cylinders wherein, for each crankshaft rotation, rough running values are determined by measuring segment times, the segment times including the times, which correspond to the piston movement of individual cylinders after their ignition time point, wherein the crankshaft passes through an associated circular segment angular region. A combustion misfire is determined in the affected crankshaft circular segment regions from the determined rough running values LUT for crankshaft segment regions having several simultaneously igniting cylinders via a desired value comparison to a threshold value SW, which is lower in value than the threshold value SWfor the misfire check in crankshaft segment regions having individually igniting cylinders. For a combustion misfire in a crankshaft segment region having simultaneously igniting cylinders causing a misfire operation in one of these cylinders, a misfire operation is caused by a suitable engine intervention and by measuring the change of the rough running values in the crankshaft segment region having the simultaneously igniting cylinders, the cylinder is determined by the engine intervention which exhibits a combustion misfire without engine intervention.

Method for engine misfire detection in multi-cylinder internal combustion engines with multi-cylinder spark ignition

A method for detecting combustion misfires for internal combustion engines is introduced wherein an index for the rough running of the engine is formed and is compared to a threshold value. The threshold value is dependent upon the load of the engine. Exceeding the threshold value is evaluated as a misfire. The method is characterized in that the threshold value, in addition to being dependent upon the load, is also dependent upon the ignition angle and/or the lambda value or that the formation of the index for the rough running also takes place in dependence upon the ignition angle and/or on the lambda value; and/or that the activation/deactivation of the misfire detection is at least dependent upon the ignition angle and/or on the lambda value.

Method for detecting combustion misses

The invention relates to a method for detecting combustion misfires in a multi-cylinder internal combustion engine. Combustion misfires are detected from data for the rough running of individual cylinders via a comparison with threshold values at operating points stored in a characteristic field. These data are determined within the engine. The combustion misfire detection is suppressed below an rpm-dependent zero-load characteristic line. The zero-load characteristic line is continuously adapted to the actually present lowest load at corresponding rpm values during vehicle operation.

Method for detecting combustion misfires in a multi-cylinder internal combustion engine

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Stuttgart-Weilimdorf, Germany

Heiko Oertel