A method for the injector-individual adaption of the injection time of motor vehicles is based on linking the IIC method and the MFMA method. Before starting to drive, the IIC method is carried out, and while driving MFMA measurements are carried out. The measurement points obtained are used as subsequent measurement points for the IIC function. Thus injector-individual characteristic fields can be determined, in which deviations due to manufacturing and also aging and wear of the components during the service life are considered.