Discovery II
ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-33
Fuel injectors
The fuel injectors are located beneath the air inlet manifold. They utilise an electrical solenoid to lift the injector needle
off its seat to allow fuel injection to take place. The fuel injectors provide excellent fuel atomisation in the lower portion
of the inlet manifold, the air/fuel mixture can then be drawn into the cylinders to give good combustion characteristics
and therefore excellent driveability.
There are eight fuel injectors one per cylinder that the ECM operates sequentially. All the injectors are fed from a
common fuel rail as part of the returnless fuel system. Fuel pressure is maintained at a constant 3.5 bar (52 lbf.in
2
) by
a regulator that is integral with the fuel pump.
FUEL DELIVERY SYSTEM - V8, DESCRIPTION AND OPERATION, Description.
Input/Output
All eight fuel injectors are supplied with battery voltage via fuse number 1 located in engine compartment fuse box.
The ECM controls the individual earth path for each injector via its own pin at connector C0636 of the ECM multiplug.
This facility allows the ECM to control the fuel injectors so that sequential fuel injection can take place.
Typical hot engine injector pulse width values:
l
Idle = 2.5 ms.
l
Peak torque (3000 rev/min) = 7 ms The ECM controls injector earth as follows:
l
Cylinder No 1 - pin 41 of connector C0636 of the ECM multiplug.
l
Cylinder No 2 - pin 1 of connector C0636 of the ECM multiplug.
l
Cylinder No 3 - pin 27 of connector C0636 of the ECM multiplug.
l
Cylinder No 4 - pin 40 of connector C0636 of the ECM multiplug.
l
Cylinder No 5 - pin 2 of connector C0636 of the ECM multiplug.
l
Cylinder No 6 - pin 15 of connector C0636 of the ECM multiplug.
l
Cylinder No 7 - pin 14 of connector C0636 of the ECM multiplug.
l
Cylinder No 8 - pin 28 of connector C0636 of the ECM multiplug.
Individual injectors can be measured for resistance using a multimeter. An acceptable injector resistance is as follows:
l
14.5
±
0.7 ohms at 20
°
C (68
°
F).
The fuel injectors can fail in the following ways or supply incorrect signal:
l
Injector actuator open circuit.
l
Short circuit to vehicle supply.
l
Short circuit to vehicle earth.
l
Blocked injector.
l
Restricted injector.
l
Low fuel pressure.