Audi A2 User Manual

247

Service.

AUDI A2 - Engine and Gearbox

Design and Function

For internal use only.

Self-study programme 247

Contents

Overview

Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 l - TDI (55 kW) AMF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.4 l - 16 V (55 kW) AUA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Engine

Design and function of the 1.4 l - 16 V engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

System overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Lambda control of the Euro-On-Board Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 21

Functional overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Page

Gearbox

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Gearbox design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Double synchronisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Gear shifting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Actuators and sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

The self-study programme will provide you with information on design and functions.

It is not intended as a workshop manual!

For maintenance and repairs please refer to the current technical literature.

New

Attention Note

Overview

Engine

1.4 l - TDI (55 kW) AMF

Technical data

Engine code: AMF

SSP247_071

Power output [kW]

10000 2000 3000 4000 5000 6000

Firing order: 1 - 2 - 3

200

180

160

140

120

100

Torque [Nm]

SSP247_072

Design: Turbocharged three-

cylinder in-line engine

Capacity: 1422 cm

Power output: 55 kW (75 PS)

at 4000 rpm

Torque: 195 Nm at 2200 rpm

Bore: 79.5 mm

Stroke: 95.5 mm

Compression: 19.5 : 1

Weight: 130 kg

Please refer to SSP 223 for the design and function of the 1.4 l TDI pumpnozzle engine.

Mixture Direct injection with induction: pump-nozzle unit

Turbocharger: Garrett GT 12 turbocharger

with wastegate

Exhaust emissions Oxidising catalytic control: converter and exhaust gas

recirculation

Exhaust emissions standard:EU 3

Fuel: Diesel, cetane rating at

least 49 CN, RME

The engine code and engine number are located on the front engine/gearbox ﬂange.

SSP247_026

1.4 l - 16 V (55 kW) AUA

200

Technical data

Engine code: AUA

SSP247_001

Power output [kW]

10000 2000 3000 4000 5000 6000

Firing order: 1 - 3 - 4 - 2

180

160

140

120

100

SSP247_002

Torque [Nm]

Design: Four cylinder in-line engine

Petrol engine

Capacity: 1390 cm

Power output: 55 kW (75 PS)

at 5000 rpm

Torque: 126 Nm at 3800 rpm

Bore: 76.5 mm

Stroke: 75.6 mm

Compression: 10.5 : 1

Weight: 90 kg

Mixture Electronic, sequential induction: multipoint injection,

adaptive idlecontrol, deceleration fuel cut-off

Ignition system: Distributorless ignition

system with static highvoltage distribution, longlife spark plugs

Exhaust emissions control: 3-way catalytic converter,

2 heated lambda probes, activated charcoal ﬁlter

Exhaust emissions standard: EU 4

Fuel: Petrol, unleaded, 95 RON

SSP247_069

– Lambda control with probes

upstream and downstream of the catalytic converter

– Electric exhaust gas recirculation

valve

– Valve actuation via rocker arms

Overview

Gearbox

02T gearbox

SSP247_073 SSP247_074

The 02T gearbox is an extremely lightweight two-shaft gearbox. The parts of the housing are made of magnesium.

02J gearbox

The familiar 02J gearbox is used in the A2 1.4 l TDI, for torques up to 250 Nm.

It is designed to transmit torque values of up to 200 Nm.

Both gearboxes are actuated via gear selector cables and gate selector cables.

SSP247_075 SSP247_076

Design and function of the

1.4 l - 16 V engine

The cylinder block

Engine

The cylinder liners are made of cast iron. They are cast into the crankcase and can be reworked.

is made of die-cast aluminium.

The required stiffness is achieved by pronounced ribbing, and is further reinforced by the crankshaft bearing blocks.

G12 is the only approved coolant additive. As well as preventing frost damage on the aluminium housing, it prevents the formation of lime deposits and damage due to corrosion in the coolant channels.

The crankshaft

The webs with the cast cylinder liners have a thickness of 5.5 mm.

SSP247_003

is made of cast iron and is equipped with four balancer weights. Despite this weight saving, the crankshaft has the same running characteristics as crankshafts with eight balancer weights.

The bearing blocks support the internal stiffness of the aluminium cylinder block.

The crankshaft must not be loosened or removed. If the bearing cap bolts are released then the internal structure of the bearing blocks in the cylinder blocks slackens and causes them to warp. The bearing clearance is then reduced.

SSP247_004

If the bearing cap bolts are released then the complete crankcase with crankshaft needs to be replaced. It is not possible to measure the bearing clearance of the crankshaft using standard workshop equipment.

Engine

Camshaft drive

The two camshafts are driven by two toothed belts.

Due to the narrow width of the cylinder head, the toothed belt drive is divided into a main drive and a coupled drive.

Coolant pump

Main drive

The main toothed belt drive transmits the drive from the crankshaft to the coolant pump and the intake camshaft. An automatic tensioning roller and two idler rollers prevent the toothed belt from vibrating.

Coupled drive

The toothed belt of the coupled drive is located directly behind the toothed belt of the main drive, outside the camshaft housing.

The coupled drive transmits the drive from the intake camshaft via the toothed belt to the exhaust camshaft.

belt pulley

Toothed belt

- main drive

Idler roller

Main drive tensioning roller

Intake camshaft toothed belt sprocket

Toothed belt coupled drive

Tensioning roller for coupled drive

Idler roller

Crankshaft toothed belt sprocket

SSP247_005

Coupled drive

Exhaust camshaft toothed belt sprocke

Here again an automatic tensioning roller prevents the toothed belt from vibrating.

Guide holes are provided in the camshaft housing and at the camshaft toothed belt sprockets for assembly and for adjusting the valve timing. The two toothed belt sprockets are secured with a special tool. Please refer to the repair manual for more details.

SSP247_006

Guide holes

SSP247_007

Valve gear

The intake camshaft and the exhaust camshaft run on bearings in the camshaft housing.

At the same time the camshaft housing also acts as the cylinder head cover.

The camshafts run on 3 bearings and are pushed into the camshaft housing. The axial clearance is limited by the camshaft housing and the blanking plugs.

The liquid sealer must not be applied too liberally, as excess material can enter the oil bores and cause engine damage.

Intake camshaft

Cylinder head

Blanking cap

Exhaust camshaft

Camshaft housing

SSP247_008

Exhaust camshaft

Cylinder head

Valve actuation

In this generation of engines, the valve actuation and the valve clearance compensation are provided by means of a rocker arm with a hydraulic support element.

Advantages

– reduced friction – less weight to move

Design

Hydraulic support element

Roller bearing of cam roller

The rocker arm consists of a pressed metal lever and a cam roller with roller bearing. It is clipped in at the support element and laid onto the valve.

SSP247_009

Camshaft

Cam roller

Rocker arm

Valve

SSP247_010

Engine

Hydraulic support element

Design

Piston with bore

The support element consists of:

– a piston – a cylinder and – a piston spring

It is connected to the engine oil circuit. A small ball with a spring forms a one-way valve in the lower oil chamber.

Function during valve clearance compensation

In the event of excessive valve clearance the piston is pushed out of the cylinder by the piston spring until the cam roller lies up against the cam. While it is being pushed out the oil pressure in the lower chamber reduces.

The one-way valve opens and oil ﬂows in.

Oil channel

Piston spring

One-way valve

Cylinder

Upper oil chamber

Lower oil chamber

SSP247_011

Valve clearance

Once the pressure difference between the lower and upper oil chamber has been equalised the one-way valve closes.

Valve lift

When the cam runs onto the cam roller the pressure in the lower oil chamber increases. The trapped oil cannot be compressed, which means that the piston cannot be pushed any further into the cylinder.

The support element becomes a rigid element which acts as a support for the rocker arm.

The corresponding valve opens.

SSP247_012

SSP247_013

Lubrication

is provided via the hydraulic support element. The rocker arm has a bore through which oil is sprayed onto the cam roller.

Oil bore in the support element

Oil channel in the cylinder head

Function during valve actuation

The support element acts as a pivoting point for the motion of the rocker arm. The cam runs on the cam roller and presses the rocker arm downwards. The valve is then actuated via the rocker arm.

Oil

Cam roller

SSP247_014

Cam

Cam roller

The lever arm between the cam roller and the support element is shorter than between the valve and the support element. This means that a relatively small cam can achieve a large valve lift.

The hydraulic support elements cannot be checked.

Rocker arm

SSP247_015

Engine

Electric exhaust gas recirculation valve

EGR valve N121

Exhaust manifold

EGR valve N121 is electrically controlled and actuated directly by engine control unit J537.

Pressure equalisation

Supply line to intake manifold

SSP247_016

A stainless steel pipe connects the valve with the intake manifold.

The valve is ﬂanged directly onto the cylinder head and directly connected to the exhaust duct of cylinder no. 4 by means of a channel in the cylinder head.

The high temperatures caused by the exhaust gases are transferred to the cylinder head and cooled by the coolant ﬂowing through.

Functional diagram

Air cleaner

Intake manifold

N121

G212

J537

°C

1/min

MPa

Even in normal operation of the engine a certain amount of residual gas leaks from the combustion chamber into the intake manifold when the valves are rocking.. In the subsequent induction process a proportion of the residual gas is then drawn in with the fresh mixture (internal exhaust gas recirculation).

Up to a certain degree the residual gas (exhaust gas) can have a positive effect on reducing the amount of nitrogen oxides in the exhaust, and it can help to convert energy more efﬁciently (reduced fuel consumption).

The additional exhaust gas recirculation helps to reduce NO

emissions (nitrogen oxides)

further and to lower fuel consumption.

To do this, a certain amount of exhaust gas is taken and fed back to the intake air via EGR valve N121. This is called “external” exhaust gas recirculation.

Supply line to intake manifold

Engine load

SSP247_017

In order to optimise the distribution of recirculated exhaust gas and induced fresh air, the exhaust gas emerges into the fresh air ﬂow directly under the middle of the throttle valve, at two holes positioned at right angles to the intake air ﬂow.

EGR valve N121 is actuated by engine control unit J537 according to a deﬁned map. It takes information such as engine speed, engine load, air pressure and coolant temperature into account.

EGR potentiometer G212 informs the engine control unit of the cross-section of the opening.

With the exhaust gas recirculation active the amount of gas that can be recirculated is limited to 18 % of the intake air quantity. There is no exhaust gas recirculation in idle, in overrun or during engine warm-up up to

Engine

Function

Potentiometer

Anchor

Coil

Exhaust gas from engine

Pressure equalisation via air cleaner

The EGR valve terminates (zero-current process) the recirculation of exhaust gases to the intake manifold. It is switched on from a coolant temperature of 35 When it is actuated, the valve is opened with a deﬁned duty cycle.

The input information includes

– information about the engine speed – information about the load status of the

engine – coolant temperature – air pressure

A potentiometer is located in the valve head.

This potentiometer detects the opening cross-section of the valve, which is passed back as a return message to the engine control unit. The opening cross-section is then used to control the voltage of the coil in the valve according to the map.

Valve

Electrical circuit

To intake manifold

SSP247_018

SSP247_019

A direct connection to ambient air pressure is provided via the air cleaner to allow for pressure equalisation in the valve during the different control phases.

Diagnostics

The valve has diagnostic capabilities.

The following are stored in the fault memory:

– Zero point shift – Maximum opening – Maximum path

It is also detected if a valve is sticking.

G212 EGR potentiometer J537 Control unit for 4LV N121 Frequency valve for exhaust gas

recirculation

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