During production, the injectors are subdivided into three different classifications. The classification refers to the tolerance zone position of the injectors as regards the injection rates. Injectors of only one classification are fitted on a certain engine. The injector classification can be seen on the injectors.
There are the following classifications:
So that the DDE control unit can calculate the ideal injection rates, the right value must be stored in the calibration of the injector classification. If the incorrect value is stored, the running characteristics and emissions values deteriorate.
In the case of replacement of individual injectors, injectors of the right classification must be fitted.
The calibration of the injector classification only needs to be carried out if the DDE control unit has been replaced due to a defect and had no communication capability. In this case, the injector classification must be read from the injectors and stored using the calibration.