Magneti Marelli France

Christophe Genin

Philippe Wallerand

Gas torque (Cg) is determined for each cylinder combustion. Engine speed (N) and air admission manifold pressure (Pca) are measured during the corresponding prior admission phase. A reference torque (Cref), which is a function of N and Pca, is cartographically calculated by interpolation. The reference torque Cref, for example, is corrected by multiplication with a coefficient (KM) associated with the corresponding cylinder in a stabilized engine operating mode. In a transient mode, an additive correction (KA) is also made to derive the expected theoretical torque (Cpr), which is compared with the gas torque (Cg) so as to determine that misfire has occurred if Cpr/Cg>S2, where S2 is a threshold value. The process and device are suitable for generating signals representative of engine operation or indicating that the threshold level of harmful components discharged into the exhaust gases is exceeded.

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Noisiel, France

Christophe Genin