Patent ID: 7072760

Claim:
A method of detecting misfires of a mixture between a fuel and an oxidizing agent, in any one of the cylinders of an internal combustion engine having multiple-stroke operating cycles, such as two-stroke or four-stroke cycles, this method comprising the following steps: a) during at least some of the combustion phases in at least one of the cylinders, at an instant (t) of the engine operating cycles, a current value of an index I n (t) representative of operating irregularities in the engine stroke is calculated, b) while the engine is operating, and on the basis of the current value at the instant t of the index I n (t), the current value at the same instant t of an observation function G(t) is calculated, this function being a function of an instantaneous discrepancy between said current value at the instant t of the index I n (t) and an estimated reference value Ī n+i (t) illustrative of this index at a different instant, c) the current value of G(t) is compared with a predetermined threshold (S) dependent on the engine load (C) and/or speed (N), and d) a misfire is diagnosed when the value of G(t) crosses the threshold (S), characterized in that: the observation function G(t) is such that: G ( t )= Ī n ( t )− I n ( t ), with Ī n ( t )= Ī n+i ( t )+ a×E n ( t ) Ī n (t) corresponding to a value representative of the index I n (t) after the values of this index that lie outside a predetermined permissible discrepancy (BC) have been excluded and/or weighted and where a is a correction coefficient dependent on |E n (t)|, and E n (t)=I n (t)−Ī n+i (t), i being an operating cycle different from n , E n (t) being an expression of the instantaneous discrepancy between said current value at the instant t of the index I n (t) and the corresponding reference value Ī n+i (t) illustrative of this index at a different instant.