Unlike conventional gasoline port fuel injection systems,
the desired fuel rail pressure for the direct injection
system ranges widely over various engine operating
conditions. The high pressure fuel pump receives fuel
from the fuel pump assembly (in tank), and increases
the fuel pressure delivering it to the fuel rail.
NOTE: When the high pressure fuel pump is removed
the retaining bolts must discarded and a new bolts
installed, refer to the WSM for more information.
E217869
1
2
4
3
High pressure fuel pump
1
Fuel volume control valve (integral to the high
pressure fuel pump)
2
Fuel rail pipe connection (outlet)
3
Fuel line to fuel tank connection (inlet)
4
The fuel volume control valve is a solenoid valve
permanently mounted to the pump assembly. The PCM
commands the fuel volume control valve to meter in a
specified fuel volume with each pump stroke. The PCM
regulates the fuel volume into the rail to achieve the
desired fuel rail pressure.
The fuel volume control valve is synchronised to the
cam position on which the pump is mounted. The PCM
takes into account that camshaft phasing which varies
during engine operation.
The fuel pressure sensor is a 3 wire variable capacitance
sensor located at the end of the fuel rail. The PCM
supplies a 5 volt reference (VREF) signal which the
FRP sensor uses to produce a linear analog voltage
indicating fuel pressure.
The primary function of the FRP sensor is to provide
fuel rail pressure feedback to the PCM. The PCM
monitors FRP sensor as the engine is operating to
control fuel pressure.
This is a closed loop function which means the PCM
continuously monitors and adjusts for ideal fuel rail
pressure determined by conditions such as engine load,
speed and temperature. The fuel rail pressure can be
monitored using IDS.
Fuel Injectors
E217868
The direct fuel injection fuel injector delivers fuel
directly into the cylinder under high pressure. Each
injector is controlled by 2 circuits from the PCM.
A boosted voltage supply, up to 65 volts, is generated
in the PCM and used to initially open the injector. The
injector driver controls three transistor switches that
apply the boost voltage to open the injector and then
modulates the current to hold the injector open.
The PCM contains a smart driver that monitors and
compares high side and low side injector currents to
diagnose numerous concerns. Each fuel injector high
side circuit is paired inside the PCM with another fuel
injector high side circuit.
Service Training
38
Lesson 3 – Powertrain
Fuel Charging and Controls
