Download SSP 491 Audi 1.4l TFSI Engine With Dual Charging PDF

TitleSSP 491 Audi 1.4l TFSI Engine With Dual Charging
File Size4.3 MB
Total Pages44
Document Text Contents
Page 1



Vorsprung durch Technik

Service Training



1.4l TFSI Engine with Dual Charging

All rights reserved.

Technical specifi cations are subject to





[email protected]


D-85045 Ingolstadt

Technical status 02/11

Printed in Germany


Self Study Programme 491

Page 2


The 1.4l 136kW TFSI engine is a top-of-the-range addition to the

Audi A1 series.

The combination of a Roots blower and exhaust gas turbocharging

is refl ected in spontaneous throttle response and high pulling

power, even at high driving speeds.

The Roots blower cuts in at 1500 rpm and, in most situations, cuts

out again at 2400 rpm.

At the latest by 3500 rpm, the turbocharger does all the work.

Since it has little work to do at low engine speeds, the Roots

blower is large in size and designed for high effi ciency.

Thanks to TFSI* technology, which combines effi ciency and dynam-

ics, all Audi models featuring the new 1.4l 136 kW TFSI engine

continue Audi's successful concept of downsizing*.

In the Audi A1, the engine consumes on average just 5.9 litres of

fuel per 100 km. Specifi c power output is 97.8 bhp per litre, yet

emissions are only 139 g/km.

Petrol direct injection, the Roots blower and the turbocharger

make for a perfect combination. The engine is rated for a high

compression ratio of 10.0 : 1. This enhances thermodynamics,

resulting in increased power output and economy.

The three-door Audi A1 with 1.4l 136kW TFSI engine sprints from

zero to 100 kph in 6.9 seconds and has a top speed of 227 kph.

Learning objectives of this Self Study Programme:

In this Self Study Programme you will learn about the technology

of the 1.4l 136kW TFSI engine.

When you have worked your way through this Self Study Pro-

gramme, you will be able to answer the following questions:

• How is the basic engine designed?

• What are the diff erences between the 1.4l 136kW TFSI engine

and the TFSI engines used previously by Audi?

• How does the engine's air supply system work?

• What are the points to note when servicing the vehicle?


Page 22


Roots blower


491_029 491_030


The Roots blower is activated when required and driven by the

coolant pump via an auxiliary drive.

The auxiliary drive is activated by a maintenance-free solenoid

coupling on the coolant pump module.

If the solenoid coupling is deactivated, three lead springs pull the

friction plate back into the initial position.

Due to the high forces involved, "clicking" of the solenoid coupling

is normal. This can occur at engine speeds of up to 3400 rpm.

Due to the ratios from the crankshaft pulley to the Roots blower

pulley, as well as the internal ratio of the Roots blower, the Roots

blower rotates at fi ve times the speed of the crankshaft.

The maximum speed of the Roots blower is 17,500 rpm.

Mechanical Roots blower

The mechanical Roots blower is bolted onto the cylinder block

downstream of the air fi lter on the intake manifold side.

The Roots blower is also known as a screw compressor due to the

shape of its two rotors.

Unlike in the 3.0l V6 TFSI engine, the rotors do not have three

vanes, rather four.


compressor solenoid

coupling N421

Roots blower

belt drive

Tensioner pulleyRoots blower

Roots blower




Coolant pump


Ratio step

Synchronous step


Suction sidePressure side


Charge pressure is regulated by a control fl ap control unit. The

maximum charge pressure which the Roots blower can generate is

1.75 bar (absolute).


For further information about the design of Roots blowers, refer to Self Study Programme 437 "Audi 3.0l V6 TFSI Engine

with Roots Blower".

Page 23


Solenoid coupling

In addition to its typical function of delivering coolant, the coolant

pump has an integrated solenoid coupling for activating the

mechanical Roots blower.

The coolant pump, alternator and AC compressor are driven by the

six-groove primary pulley. The fi ve-groove poly V-belt of the sec-

ondary pulley drives the air compressor of the coolant pump.

The compressor solenoid coupling N421 establishes a frictional

connection with the Roots blower drive. The pulley of the coolant

pump is bolted to the drive shaft of the coolant pump. The pulley

for driving the Roots blower rotates on the ball bearings. The

solenoid coil is fi rmly connected to the coolant pump housing.

Compressor solenoid coupling not actuated

The electrical circuit of the solenoid coil is not closed. As a result, a

frictional connection is not established (air gap A) due to the

spring force between the friction plate and friction lining. The

stationary pulley runs freely on the ball bearings.

Compressor solenoid coupling actuated

The electrical circuit of the solenoid coupling is closed by the

engine control unit The magnetic force pulls the friction plate

against the coupling lining. The coolant pump pulley is now fric-

tionally connected to the Roots blower pulley.

Comfortable starting of the compressor

To ensure that the compressor solenoid coupling operates

smoothly, the electrical current characteristic is evaluated while

the solenoid coupling is being activated.

For this purpose, a corresponding sensor installed in the engine

control unit. The measured value is compared to a characteristic

map, and a wear value is assigned to the coupling. To ensure soft

and comfortable starting, the activation pulse (PWM signal) is

adapted by the engine control unit according to wear.

Adapted values are stored in the control unit. If the coolant pump

is replaced, this adapted value must be reset. For this purpose,

there is a corresponding test routine in the Guided Fault Finding

which is indicated in the Workshop Manual "Engine Mechanicals".




Roots blower

belt drive

Friction plate

Solenoid coil


pump vane

Coupling lining


pump vane

Page 43


Self Study Programmes

This Self-Study Programme summarises all the key information you need to know about the 1.4l 136kW TFSI engine. You will fi nd further

information about the subsystems mentioned in this document in other Self-Study Programmes.

SSP 384 SSP 384 Audi chain-driven 1.8l 4V TFSI engine, order number: A06.5S00.29.20

• TFSI engine technology

SSP 432 The Audi 1.4l TFSI engine, order number: A08.5S00.48.20

• Engine mechanicals

• Oil circuit

• Operating principle of the high-pressure fuel pump

SSP 437 Audi 3.0l V6 TDI engine with Roots blower, order number: A08.5S00.53.20

• Basic information on Roots blowers




SSP 477 Audi A1, order number: A10.5S00.70.20

• Topology

SSP 485 The Audi 1.2l TFSI engine, order number: A10.5S00.78.20

• Dual-circuit cooling system


Page 44



Vorsprung durch Technik

Service Training



1.4l TFSI Engine with Dual Charging

All rights reserved.

Technical specifi cations are subject to





[email protected]


D-85045 Ingolstadt

Technical status 02/11

Printed in Germany


Self Study Programme 491

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