Method of and an apparatus for misfire and rough road detection

摘要

Engine speed variations following combustion events within the cylinders of a multi-cylinder internal combustion engine are compared with a threshold during a predetermined number of combustion events. A distribution of speed variations exceeding the threshold with respect to the cylinders is formed. The distribution is analyzed to determine whether misfire is occurring, as indicated by speed variation following combustion occurring in half or less than half of the cylinders, or whether the vehicle is driving over a rough surface, as indicated by speed variation following combustion occurring in more than half of the cylinders.