Method of detecting combustion misfires

A method for detecting combustion misfires in an internal combustion engine on the basis of a first signal wherein the nonuniformity of the rotational movement of the crankshaft of the engine is imaged, the method comprising the steps of:

• providing said first signal as a discrete first signal as a sequence of segment times (ts) which are discretely detected in accordance with the sequence of ignitions of said engine;
• generating a second signal which is periodic and has a period duration corresponding to one of the following:
• the cycle duration of a complete work cycle of said engine or said cycle duration divided by a whole number and said second signal having a fixed phase relationship to the rotational movement of said crankshaft;
• providing an ancillary signal based on said first signal;
• modulating said second signal with said ancillary signal and filtering said second signal to form a third signal;
• and,
• utilizing said third signal for detecting the presence of misfires and for identifying the cylinder affected by said misfires.