Method for diagnosing the operation of a motor vehicle diesel engine injector

1. A method for diagnosing the operation of at least one injector of a diesel engine of a motor vehicle, said injector being controlled by at least one control law on the basis of at least one operating parameter of the injector, the method comprising

measuring a value of said operating parameter during use of said injector, and

determining an efficiency value of the injector on the basis of the measured value of the parameter and of a predetermined reference curve representing the efficiency of the parameter in its interval of operating values,

the injector being controlled by a plurality of control laws on the basis of at least one operating parameter of the injector, the at least one operating parameter of the injector being different for each of the control laws,

determining an efficiency value of each control law on the basis of the measured value of said at least one parameter of the respective control law and of a predetermined reference curve representing the efficiency of said parameter in its interval of operating values, and wherein the efficiency value of the injector is determined on the basis of the efficiency value of each of the control laws.

2. A method for diagnosing the operation of at least one injector of a diesel engine of a motor vehicle, said injector being controlled by at least one control law on the basis of at least one operating parameter of the injector, the method comprising:

measuring a value of said operating parameter during use of said injector, and

determining an efficiency value of the injector on the basis of the measured value of the parameter and of a predetermined reference curve representing the efficiency of the parameter in its interval of operating values,

the injector being controlled by a plurality of control laws on the basis of at least one operating parameter of the injector for each of the control laws,

determining an efficiency value of each control law on the basis of the measured value of said at least one parameter and of a predetermined reference curve representing the efficiency of said parameter in its interval of operating values, and wherein the efficiency value of the injector is determined on the basis of the efficiency value of each of the control laws,

wherein the determination of the efficiency value of the injector is calculated on the basis of the average of the efficiency of the various parameters, the average of the efficiency of the parameters being weighted by the most representative parameters in order to diagnose the operation of the injector.

3. The method as claimed in claim 1 , comprising a preliminary step of determining the reference curve.

4. The method as claimed in claim 3 , wherein the reference curve is determined empirically.

5. The method as claimed in claim 1 , wherein the different operating parameters of the injector for each of the control laws are chosen from among: the drift in the electric supply voltage to the injector, the flow of fuel supplied by the injector at a predetermined operating point of the injector and the drift of the fuel injection time of the injector.

6. The method as claimed in claim 1 , wherein, with the injector being controlled by the control law on the basis of a plurality of operating parameters of the injector, the measurement is performed for each of said operating parameters during use of the injector, and the efficiency value of the injector is determined for each parameter on the basis of the measured value of said parameter and of a predetermined reference curve representing the efficiency of said parameter in its interval of operating values.

7. A method for diagnosing the operation of at least one injector of a diesel engine of a motor vehicle, said injector being controlled by at least one control law on the basis of at least one operating parameter of the injector, the method comprising:

measuring a value of said operating parameter during use of said injector, and

determining an efficiency value of the injector on the basis of the measured value of the parameter and of a predetermined reference curve representing the efficiency of the parameter in its interval of operating values,

the injector being controlled by a plurality of control laws on the basis of at least one operating parameter of the injector for each of the control laws,

determining an efficiency value of each control law on the basis of the measured value of said at least one parameter and of a predetermined reference curve representing the efficiency of said parameter in its interval of operating values, and wherein the efficiency value of the injector is determined on the basis of the efficiency value of each of the control laws, and

limiting the determined efficiency value of the injector if at least one of the parameters has not been measured.

8. A method for diagnosing the operation of a diesel engine of a motor vehicle, the engine comprising a plurality of injectors, the method comprising:

for each injector, implementing the method, as claimed in claim 1 , for diagnosing the operation of an injector, and

diagnosing the operation of the engine on the basis of the efficiency of the operation of each of the injectors of the engine.

9. The method as claimed in claim 8 , further comprising displaying the efficiency value of the operation of the engine, wherein said efficiency value of the operation of the engine is determined on the basis of the efficiency value of the operation of each of the injectors.

10. A motor vehicle comprising a diesel engine comprising at least one injector and an electronic control unit for said engine, said electronic control unit being designed to implement the method for diagnosing the injector as claimed in claim 1 .

11. The method as claimed in claim 2 , comprising a preliminary step of determining the reference curve.

12. A motor vehicle comprising a diesel engine comprising at least one injector and an electronic control unit for said engine, said electronic control unit being designed to implement the method as claimed in claim 8 .