SSANGYONG RODIUS 2004.09 Manual page 255

09-18
1491-01
7. INDIVIDUAL INJECTOR CALIBRATION (C2I)
Injected fuel is proportional to square root of injection time and rail pressure.
It is function between pulse and rail pressure and fuel injection curve is called injector
characteristics curve having the following shape.
Common rail injectors are very accurate components. They are able to inject fuel delivery
between 0.5 to 100 mg/str under pressure varying from 150 to 1600 bar.
This high level of accuracy requires very low machining tolerances (few ㎛).
Nevertheless, due to the machining dispersion, the loss of charge through the functional
orifices, the friction between moving parts and electromagnetic field level are different from one
injector to the other. So, the difference of fuel delivery for the same pressure and the same
pulse can reach 5 mg/str from one injector to the other. It is impossible to control efficiently the
engine with such a dispersion between the different injectors. It is necessary to add a correction
that allows injecting the demanded fuel delivery whatever the initial hydraulic characteristics of
the injector
is. The method consists in correcting the pulse that is applied to the injector with an offset that
depends on the initial hydraulic map of the injector. So, the pulse should be corrected according
to characteristics of each injector.
ENGINE CONTROL SYSTEM
RODIUS 2004.09