Isuzu 2008MY N Series Workshop Manual page 390

Electronic control type injectors controlled by the ECM
are used. Compared with conventional injection
nozzles, a command piston, solenoid valve, etc. are
added.
ID codes displaying various injector characteristic are
laser marked in the plate, and ID codes showing these
in numeric form (30 alphanumeric figures are displayed
and only 24 are used). This system uses fuel injector
flow rate information (ID codes) to optimize injection
quantity control. When an injector is newly installed in a
vehicle, it is necessary to input the ID codes in the
ECM.
QR (Quick Response) codes or fuel injector flow rate
(ID codes) have been adopted to enhance the injection
quantity precision of the injectors. The adoption of
codes enables injection quantity dispersion control
throughout all pressure
improvement in combustion efficiency and reduction in
exhaust gas emissions.
Return port
Solenoid
TWV
Outlet orifice
Control chamber
Inlet orifice
Command piston
Nozzle
1) Non-injection state
The two way valve (TWV) closes the outlet orifice by
means of a spring force, when no current is supplied
from the ECM to the solenoid. At this time, the fuel
pressure applied to the nozzle leading end is equal to
the fuel pressure applied to the control chamber
through the inlet orifice. As for the force competition in
this state, the pressure on the command piston upper
surface + nozzle spring force defeat the pressure on
the nozzle leading end, and consequently the nozzle is
pushed downward to close the injection holes.
ranges, contributing
Driving current
From fuel rail
Pressure in
control chamber
Injection rate
No injection
Engine Control System (4HK1)
to
Driving current
Pressure in
control chamber
Injection
2) Injection start
The TWV is pulled up to open the outlet orifice, and
thus the fuel leaks toward the return port, when the
current is supplied from the ECM to the solenoid. As a
result, the nozzle is pushed up together with the
command piston by the fuel pressure applied to the
nozzle leading end, and then the nozzle injection holes
open to inject the fuel.
1A-387
Driving current
Pressure in
control chamber
Injection rate
Injection end
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