Method for determining a functioning parameter of an engine

Process for the determination of an operating parameter (α) of an internal combustion engine as a function of three control parameters (N, P, λ) of this engine, said process consisting in:

• establishing a first map (C1) of the operating parameter (α) as a function of two of the control parameters (N, P), the third control parameter (λ) being fixed at a first value, and
• establishing a second map (C2) of the operating parameter (α) as a function of the same two control parameters (N, P), the third control parameter (λ) being fixed at a second value,
• said process being characterized in that it consists moreover in:
• establishing at the test bench a non-linear relationship f(λ) between the operating parameter (α) and the third control parameter (λ) over all the range of variation of this parameter at at least one specific operating point (N, P), and
• using this relationship to determine the operating parameter (α) as a function of the three control parameters (N, P, λ) at all operating points of the engine.