Charge Pressure Sensor G31

50

Air routing system for longitudinal mounted engines

Air filter

Charge Pressure Actuator
V465

Turbocharger

Intake Manifold Runner
Control Valve N316

Intake Air Temperature
Sensor G42 with Manifold
Absolute Pressure Sensor
G71
Throttle Valve Control
Module J338

Intake manifold

Air intake

Intake Manifold
Runner Position Sensor
G336

Charge Pressure
Sensor G31

606_038

Charge air cooler

51

Intake manifold
To accommodate both FSI and MPI fuel injectors, a newly
designed intake manifold was required. The manifold also
has pan-shaped flaps to direct air flow in the intake duct.
An angled, single piece stainless steel shaft maximizes the
torsional rigidity of the flaps. At initial launch of these
engines, the North American version will only have FSI
injection.

The shaft is actuated by Intake Manifold Runner Control
Valve N316 using a vacuum motor based on signals from the
ECM.
The pan-shaped flaps are tensioned in the manifold in such a
way to minimize excitation by the airflow.

Fuel Metering Valve N290

Intake Air Temperature Sensor
G42 with Manifold Absolute
Pressure Sensor G71

High pressure pump

Vacuum motor for intake manifold flaps

MPI injectors

Intake Manifold Runner
Position Sensor G336
606_041

FSI injectors
Intake manifold flaps

Throttle Valve Control Module J338

Intake Manifold Runner Control Valve
N316

FSI injectors
606_042

52

Turbocharger
An all new mono-scroll turbocharger is used on both the
1.8L and 2.0L versions of the third generation EA888
engine. It has the following features:

•
•
•
•
•
•
•
•

Electrical wastegate actuator (Charge Pressure Actuator
V465 with Charge Pressure Actuator Position Sensor
G581)
Oxygen sensor upstream of turbine (Heated Oxygen
Sensor G39)
Compact cast steel turbine housing with twin-scroll inlet
flanged directly onto the cylinder head
Compressor housing with integrated pulsation silencer
and Turbocharger Recirculation Valve N249
Temperature resistant Inconel turbine wheel rated for
temperatures of up to 1796 °F (980 °C)
Bearing housing with standard connections for oil and
coolant
Milled compressor wheel for higher speed resistance
and better acoustics
Turbine wheel configured as a Mixed Flow Turbine made
from Inconel 713 °C

The use of a mono-scroll turbocharger improves full throttle
response, particularly at high engine speeds. Twin-scroll
channeling of exhaust gases from the cylinder head outlets
is continued to a point just short of the turbocharger
turbine.
The turbocharger uses a Mixed Flow Turbine design. A Mixed
Flow Turbine is a compromise between a radial turbine and
an axial turbine. Exhaust gases flow radially through the
radial turbine wheel (leading edge is parallel to axis of rotation). Consequently, the turbine is suitable for handling low
flow rates, such as those typical of passenger cars. On the
other hand, exhaust gases flow axially through the axial
turbine wheel (the inlet edge is at an angle of 90° relative to
the axis of rotation). This turbine wheel is suitable for handling low flow rates, such as those typical of large displacement engines. Mixed Flow Turbines have a diagonal leading
edge. Because this type of turbine has an additional axial
impeller, which is ideal for high flow rates, a smaller impeller can also be used. The advantage of better response in the
radial turbine is combined with the higher efficiency of the
axial impeller in the upper rpm range.

Mono-scroll turbines have only one intake scroll, which
directs the exhaust gases to the impeller. In contrast to
twin-scroll turbines, they are more simple in design, lighter,
and less expensive.
Sensors for detecting air mass and air temperature:

•

Charge Air Pressure Sensor G31 is installed between the
charge air cooler and the throttle valve. Its signal is used
to monitor and control charge pressure

•

Intake Air Temperature Sensor G42 with Manifold
Absolute Pressure Sensor G71

Charge Pressure Actuator
V465
From air filter

Heated Oxygen Sensor G39
Turbocharger Recirculation
Valve N249

Cylinder head

Integrated pulsation
silencer

To charge air cooler

Cylinder block

Turbine housing Wastegate valve
Integral exhaust manifold
606_013

53

Charge Pressure Actuator V465
An electrical wastegate actuator is used in an Audi turbocharged four-cylinder engine for the first time. This technology offers the following advantages over the previously used
vacuum motors:

•
•
•

Faster and more precise response
Can be actuated independently of the charge pressure
Due to the higher closing force, the engine achieves its
maximum torque at lower engine speeds

•

The active opening of the wastegate at partial throttle
allows the basic charge pressure to be reduced. This
provides fuel savings

•

Active opening of the wastegate during the heating
phase of the catalytic converter increases the exhaust
gas temperature upstream of the catalytic converter by
50 °F (10 °C), resulting in lower cold start emissions.

•

The adjustment rate of the electrical wastegate actuator
allows the immediate build-up of charge pressure during
negative load cycles (acceleration), which has a particularly positive overall effect on the acoustic characteristics of the turbocharger (blow-off hiss and groan).

Actuating lever for the wastegate with clearance and
tolerance compensating elements on the push rod

Clearance compensating spring

Spring seat

Charge Pressure Actuator V465

54

Gear

Components of the charge pressure actuator system
The complete actuator consists of the following components:

•
•
•

Housing
DC motor (Charge Pressure Actuator V465)
Gear

•
•
•

Integral non-contact position sensor (Charge Pressure
Actuator Pressure Sensor G581)
Upper and lower internal mechanical stops in gear
Clearance and tolerance compensation elements on
push rod

Functional diagram
Connections on Charge Pressure Actuator V465:
1

Sensor + (5 V connection in engine wiring harness)

2

Actuator –

3

Ground

4

Not assigned

5

Sensor signal

6

Actuator +

1

2

4

5

6

3

606_020

Operating principle
The DC motor actuates the wastegate valve with the aid of
the gear assembly and the push rod. Movement is limited at
the lower mechanical stop by the external stop of the seated
wastegate valve, and at the upper mechanical stop by the
internal gear limiter on the housing.

ECM connection
Magnetic holder

The activation frequency of the DC motor is controlled by the
ECM and lies within a 1000 Hz band.
The push rod is adjustable for length. This allows the wastegate valve to be adjusted after replacing the actuator.

Charge Pressure Actuator Position Sensor G581
G581 is installed in the charge pressure actuator gear
housing cover. A magnetic holder with two permanent
magnets is also integrated into the housing cover and rests
on the spring seat of the gear. It therefore performs the
same movement as the push rod. When the push rod moves,
the magnets travel past a Hall sensor also located in the
housing cover. This allows actual adjustment travel to be
measured. The signal from the Hall sensor is an analog,
linear voltage signal.

Charge Pressure Actuator
Position Sensor G581
606_079
55

Turbine housing and turbine wheel

Compressor housing and compressor wheel

To meet the requirements arising from the increased exhaust
gas temperature of approximately 1796 °F (980 °C) and the
location of the oxygen sensor upstream of the turbine
housing, the turbine housing is made from a new cast steel
material.

The compressor housing has a strength-enhanced design in
order to withstand the high actuating forces produced by
Charge Pressure Actuator V465. It is made from cast aluminium. In addition to the compressor wheel, it integrates
the pulsation silencer, Turbocharger Recirculation Valve
N249, the inlet for the gases from the crankcase breather
and the fuel tank vent.

To optimize ignition sequence separation, the exhaust
routing system has a twin-scroll configuration up to a point
just before the turbine.
Since the turbine housing has a very compact design, a
standard system of studs and nuts is used to connect the
housing to the cylinder head. The turbine wheel is configured
as a mixed-flow turbine (half-radial turbine).

The compressor wheel is milled from a single piece of material. This allows a higher tolerance to high speeds and also
reduces compressor noise.

Heated Oxygen Sensor G39
Heated Oxygen Sensor G39 is a broadband type LSU 4.2
sensor. It is mounted where the exhaust gases from each
individual cylinder flow upstream of the turbine housing.

This is the most favorable position because even in this
location, temperatures are not too high.
This positioning allows for good individual cylinder recognition and permits oxygen sensor control to be enabled sooner
(six seconds) after starting the engine.

Charge Pressure Actuator V465

Flange connecting
to cylinder head

Heated Oxygen
Sensor G39
Compressor wheel

Wastegate valve
Turbocharger Recirculation
Valve N249

Turbine housing
Integrated
pulsation silencer

606_080

Turbine wheel

56

Fuel system
System overview

Fuel filter

To ECM

Ground
Battery
(positive)

Fuel Pump Control Module
J538

Transfer Fuel Pump G6

Fuel Metering Valve N290
Low Fuel Pressure Sensor G410
Low pressure fuel rail

High pressure fuel pump

Injector 2, cylinders 1 – 4
N532 – N535

Fuel Pressure
Sensor G247
High pressure fuel rail

606_017

Injector, cylinders 1 – 4
N30 – N33

Note
Only the FSI (high pressure) system will be used on the 2015 A3 engines. The use of MPI and FSI may introduced on later
Audi models.
57

Mixture formation / dual injection system
The dual injection system was developed to reduce the
particulate emissions normally associated with FSI engines.
This new fuel system is composed of a MPI (multi-port
injection) system and an FSI system.

The following goals were accomplished:
• Increase in system pressure from 2175 psi to 2900 psi
(150 bar to 200 bar)
• Reduced operational noise
• Compliance with stringent emission limits for particulate mass and volume (significant reduction in soot
emissions by a factor of 10)
• Reduction of exhaust emissions, particularly CO2,
compliance with current and future exhaust emission
standards
• Adaptation of an additional port injection system
• Improved fuel efficiency at partial throttle through use
of MPI injection system

The presentation of this information is for reference and
your interest only. The dual injection system may be used in
North American Audi models in the future but will not be
used at the introduction of the EA888 engine. The intake
manifold is the same but the ports for the MPI injectors have
not been drilled out.

High pressure system
Low pressure system

Injector 2, cylinders 1 – 4
N532 – N535
Low pressure fuel rail

Fuel Metering Valve N290

Low Fuel Pressure Sensor G410

High pressure fuel pump

Intake Air Temperature
Sensor G42 with Manifold
Absolute Pressure Sensor
G71

Throttle valve

606_012

Injector, cylinders 1 – 4
N30 – N33

High pressure fuel rail

MPI injection system

High pressure injection system

The MPI system is supplied via a flushing connection on the
high pressure pump. During MPI operation, the high pressure pump is automatically flushed with fuel and thus
cooled.

All parts in the high pressure tract have been adapted for
system pressures of up to 2900 psi (200 bar). The injectors
have been sound insulated from the cylinder head using
steel spring discs. Likewise, the high pressure rail has been
separated from the intake manifold and bolted onto the
cylinder head. The position of the high pressure injectors has
been slightly retracted. This improves homogenization of the
air-fuel mixture and reduces the thermal stress on the
valves.

To minimize pulsation, which is transmitted to the rail by the
high pressure pump, a restrictor is integrated into the flushing connection on the high pressure pump.
The MPI system has its own pressure sensor - Low Pressure
Fuel Sensor G410. Pressure is supplied on demand by the
fuel Transfer Pump G6. The Transfer Pump is activated by the
Fuel Pump Control Module J538 via the ECM. The MPI rail is
made of plastic. The MPI valves (N532 – N535) are integrated into the plastic intake manifold and optimally aligned
for fuel injection.

58

The fuel injection control concept has been modified to
ensure harmonized control for all future engines. This rule
of thumb applies to the new concept: if the plug from Fuel
Pressure Control Valve N276 is disconnected, pressure is no
longer built up in the high pressure system.

Operating modes
The ECM determines whether the engine runs in MPI or FSI
mode based on specific maps.

The objective is to achieve a lambda value of 1 across the
widest possible operating range. This is made possible by
using the integral exhaust manifold.

To minimize soot emissions, oil thinning and knock tendency,
fuel injections are thermodynamically optimized in terms of
number and type (MPI or FSI). Naturally, this affects
mixture formation. Injection timing and duration must be
adapted accordingly.

Direct injection (FSI) is used whenever the engine is started.
When the engine coolant temperature is below approximately 113 °F (45 °C) and dependent on engine oil temperature, the engine always runs in direct injection mode.

As a protective feature, a flushing function is used to
prevent coking of the fuel in the high pressure injectors
during lengthy periods of MPI operation. At the same time,
FSI mode is briefly activated.

Indicated engine torque * [Nm]

Injection type map

Engine speed [rpm]

MPI single injection

606_061

* The term indicated torque refers to the torque that a loss-free
internal combustion engine would be able to deliver.

FSI single injection
(homogeneous mode, direct injection during intake stroke)
FSI dual injection
(homogeneous stratified mode, one single direct injection
during intake stroke and one during compression stroke)

59

Engine start

Fuel efficiency advantage

A triple direct injection is performed during the compression
stroke.

When the engine is warm, optimal mixture homogenization
is ensured by advance air-fuel mixing. There is therefore
more time available for air-fuel mixture formation, resulting
in fast, efficiency-optimized combustion. In addition, no
power input is needed to drive the high pressure pump.

Warm-up / catalytic converter heating
Dual direct injection is implemented during the intake and
compression strokes. At the same time, the ignition timing is
adjusted slightly retarded. The intake manifold flaps are
closed.

Higher load
Dual injection is used here. One direct injection is performed
during the intake stroke and one during the compression
stroke.

Engine warm (> 113 °F [45 °C]) at partial
throttle
Emergency running function
The engine now switches to MPI mode. The intake manifold
flaps are also closed at partial throttle, but not 1 : 1 in MPI
mode (depending on the parameters in the engine map).

If either of these systems fails, the other system takes over
the emergency running function. This ensures that the
vehicle continues to be driveable.

Engine Control Module
J623

606_089

Animation showing MPI and FSI
operation.

60

Notes

61

Engine management system