METHOD FOR DETECTING MALFUNCTIONING TURBO-DIESEL CYLINDERS

According to the invention, a diagnostic method is provided for diagnosing a misfire condition of individual engine cylinders in a turbocharged diesel engine having at least a first and a second cylinder. The diagnostic method is characterized by defining a group of diagnosing functions (f1 . . . fn), each having as inputs a number of subsequent sampling pressure values (p1 . . . pm) and having as output a threshold characteristic (t1 . . . tn) diagnosing a misfire condition; determining an error function (e1 . . . en), which is a function of measured false fails and false passes for said diagnosed misfire condition by said diagnosing function (f1 . . . fn), in each of an engine speed region, ranging from a lowest engine speed (rlow) to a highest engine speed (rhigh), for selected engine speed range intervals (s1 . . . sl), and selecting a diagnosing function fi from the group of diagnosing functions (f1 . . . fn), where in fi having an error function ei that is lowest over the entire speed range ([rlow-rhigh]). The number n of diagnosing functions (f1 . . . fn) in the group of diagnosing functions can be more than 7.