The high pressure fuel system receives low pressure
fuel from the fuel pump assembly and delivers fuel at
high pressure to the fuel injectors.
System Operation
Direct Fuel Injection System
E210638
3
4
5
1
2
Injector nozzle outlet
1
Inlet valve
2
Spark Plug
3
Piston
4
Fuel Injector
5
Direct petrol fuel injection systems feature a
high-pressure fuel system which injects fuel directly
into the combustion chamber. The fuel/air mixture is
generated inside the combustion chamber.
Operating Modes
The direct fuel injection system fitted to 2.3L EcoBoost
engines has two different operating modes:
•
Homogeneous operating mode
•
Heat catalytic converter operating mode
Homogeneous Operating Mode
When the engine is at operating temperature, mixture
formation takes place exclusively in homogeneous
operating mode. In this mode, the injected quantity of
fuel is metered precisely to the fresh air at the
stoichiometric air to fuel ratio for petrol of 14.7:1
(Lambda 1.00).
The fuel is injected during the intake stroke here so that
enough time remains to homogenise the entire mixture.
In homogenous operating mode, the fuel charging and
combustion are similar to manifold injection.
Heat Catalytic Converter Operating Mode
The heat catalytic converter operating mode serves to
quickly heat up the three-way catalytic converter when
the engine is cold and is possible by means of twin
injection.
The first injection, as in homogeneous operating mode,
is initiated during the intake stroke. The second injection
takes place during the compression stroke, immediately
after the intake valves close. This produces a rich core
of fuel around the spark plug.
The ignition timing is retarded so that maximum
combustion heat can enter the exhaust tract to heat the
three-way catalytic converter.
NOTE: If the fuel rail pressure is too low on engine
warm up then it will not be possible to initiate the heat
catalytic converter operating mode. The injection will
be in homogenous mode and a DTC code will be set.
Component Description
Throttle Body
E219730
The throttle body system meters air to the engine during
idle, part throttle, and wide open throttle (WOT)
conditions. The throttle body system consists of single
bore with butterfly valve throttle plates and a throttle
position (TP) sensor.
(G1821522)
Service Training
36
Lesson 3 – Powertrain
Fuel Charging and Controls
