TDI DIESEL ENGINE

7/29/2019 TDI DIESEL ENGINE

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For the first time in theOCTAVIA, Skoda is offeringa modern turbodiesel engine

with direct injection.

This engine has an intelligentengine management systemto provide high output andlow fuel consumption!

... high output,

low fuel

consumption!

SP 16-1


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Technical Data 4

The TDI Engine 5

Highlights 8

System Architecture 12

Position of Components 14

System Overview 16

Sensors 18

Actuators 29

Fuel Metering Control 38

Commencement of Injection Control 40

Exhaust Gas Recirculation 42

Charge Pressure Control 44

Auxiliary Heater System 46

Glow Plug System 47

Emission Characteristics 48

Function Diagram 50

Self-Diagnosis 52

You can find information regarding inspection

and maintenance, setting and repair instructions

in the Workshop Manual

.

Contents

Service Service Service Service ServiceService

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Technical Data

Engine data:

Engine code: AGR

Type: 4-cylinder in-lineturbodiesel

Displacement: 1896 cm3

Bore: 79.5 mm

Stroke: 95.5 mm

Compression ratio: 19.5 : 1

Rated output: 66 kW (90 ch) at4000 rpm

Max. torque: 202 Nm at1900 rpm

Mixture formation: Direct injection with elec-tronically controlled distri-butor injection pump

Emission control: Exhaust gas recirculationand oxidation catalytic

convert

The 1.9-ltr. TDI engine achieves its maximumoutput of 66 kW (90 HP) at 4000 rpm.

The engine is characterized by a particularlygood torque curve. Maximum torque of 202 Nmis already available at 1900 rpm.These engine data reflect the excellent pulling

power of the engine.

SP 16-2

SP 16-3

P = OutputM = Torquen = Engine speed


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Special features of the

1.9-ltr. TDI engine

Electronic control

The quantity of fuel injected and the injection timingare controlled with the aid of the electronics to meetthe high demands in terms of fuel consumption andemissions.

This task is carried out by theE

lectronic D

iesel C

ontrol (

EDC

).It determines the quantity of fuel and the com-mencement of injection of the distributor injectionpump, controls charge pressure, exhaust gas recir-culation and glow period.

Bosch distributor injection pump VP 37 EDC with 800bar pump pressure. The distributor injection pump ispreset. The flange is pressed onto the drive shaft and

must not be removed.

Inlet port designed as swirl port. Sets the inducted airin a swirl motion, which ensures intensive swirling ofthe air in the combustion chamber.

Specially shaped piston bowl (main combustionchamber).

Injectors with two-stage fuel injection.

Charge pressure control.

Coolant pump installed in cylinder block.

Coolant thermostat installed in cylinder block.

Coolant preheated by electric auxiliary heater.

Alternator freewheeling.

Exhaust gas recirculation valve in intake manifold.

Plastic-coated injection pipes as a protection againstcorrosion.

Valve cover gasket vulcanized in place.

Oil pan with silicone sealant.

Replaceable oil filter designed as paper cartridge.

Vacuum pump driven by the camshaft.

Diesel direct injection system control unit

J248

The TDI Engine

SP 16-4


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Crankshaft

toothed belt pulley

The TDI Engine

The toothed belt drives the Camshaft Distributor injection pump Coolant pump

The required belt arc is achieved by two guide pul-leys, the tension by the semi-automatic toothed belttensioning pulley.

Brief description of mechanical components of the TDI

Setting distributor injection pump and toothed belt

Camshaft positionThe correct position is fixed by a new settinggauge. The exact middle position should bedetermined with feeler gauges.The exact camshaft position is of majorimportance for precise timing when fitting on thetoothed belt.

Injection pump gearThe position of the injection pump is fixed withthe locking drift. The injection pump gear is splitin two. A precision adjustment can be made by

slackening the 3 bolts - arrows -.

The exact procedure is described in the Workshop Manual

for the 1.9-ltr. turbodiesel engine

Camshaft gear

Injection

pump gearCoolant pump

Guide pulley

Semi-

automatic

tensioning

pulley

Locking drift

MP1-301

SP 16-5

SP 16-6

SP 16-7

Note:On no account slacken the nut for the hub of theinjection pump.If this is done, the basic setting of the injectionpump will be altered and cannot be correctly setagain with workshop tools.

Toothed belt settingAppropriate markings are provided for setting the

timing (crankshaft, camshaft, injection pump posi-tion).

Crankshaft positionMarking - top dead centre of cylinder 1 - is visibleon the flywheel through the inspection hole of thegearbox.

Note:When carrying service or repair work on the too-thed belt with the engine removed, align the mar-king on the ribbed V-belt pulley of the crankshaftwith the marking on the toothed belt cover.

Guide pulley


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The charge air cooler

The charge air cooler cools the inducted air before itenters the intake manifold. The charge air cooler isinstalled between the bumper and right wing and isforce-cooled by the airstream.

Why is the charge air cooler required?The turbocharger of the TDI engine heats the induc-ted air, which results in a loss of power of theengine.This loss of power is avoided by cooling the inductedair in the charge air cooler. The density of the airrises as the air temperature drops. The cylinders are

filled with colder and denser air which is richer inoxygen, and this in turn results in a further boost inengine output.

The cylinder head gasket is made of metal, which is why it is resistant to hig-her temperatures and pressures.The gasket can also be used in other engines of the 1.9-ltr. diesel enginerange.

SP 16-8

SP 16-9

Cylinder head gasket

Note:Take into account the differencein thickness.


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Injection nozzles

Stroke 1 +

Stroke 2

Stroke 2

Stroke 1

Spring 1

Spring 2

Nozzle needle

Two-spring nozzle holder

A gentle rise in pressure in the combustion chamber is required for minimisingcombustion noises and reducing the mechanical stresses. In addition, the fuelshould be injected not suddenly, but continuously over a lengthy period.

A two-spring nozzle holder has been developed for the 1.9-ltr. TDI engine withthe aim of achieving soft combustion. This nozzle holder injects the fuel in twostages.

Highlights

Function1st (prestroke)The nozzle holder contains two springs of different thickness. These are matchedto each other in such a way that the nozzle needle is raised only against the forceof spring 1 at the commencement of injection. As a result of the gap produced bystroke 1, only a small quantity of fuel is pre-injected at a low pressure

(p = 190 bar).This results in a gentle rise in the combustion pressure and creates the conditionsnecessary for igniting the main quantity of fuel.

2nd stage (total stroke)The injection pump constantly supplies more fuel. This results in a pressure rise inthe injection nozzle because the quantity of fuel supplied by the pump is not able toflow off through the small gap. As a result of this pressure rise, the force of spring 2is overcome and the nozzle needle raised by stroke 2 to the total stroke. As aresult of the enlarged gap, main injection occurs with the remaining quantity of fuelat a higher injection pressure (p = 300 bar).

SP 16-10

Nozzle holder

Prestroke Total stroke


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Magnetic coil

Thrust pin

Needle lift sender G80

The injection nozzle of the 3rd cylinder is equipped with a needle lift sender G80 for

detecting the commencement of injection.The sender monitors the actual moment of opening of the injection nozzle and thesignal is passed to the EDC control unit.The electronic control unit compares the incoming signal with the map for the com-mencement of injection and analyses the difference

.

Function

The needle lift sender G80 consists of amagnetic coil which is supplied with a con-stant current by the control unit. This cur-rent creates the magnetic field in the coil.

A thrust pin is located in the inside of themagnetic coil, as an extension of thenozzle needle. The movement of the thrustpin causes a change in the induced voltage

in the magnetic coil.

The moment of induction of the voltage inthe coil is compared by the control unit withthe top dead centre signal.The actual commencement of injection iscalculated from this difference. Followingthis, the "actual" value for the commence-ment of injection is compared with the "set"value, and commencement of injection iscorrected accordingly if differences exist.

Substitute function

If the needle lift sender fails, an emergencyrunning programme is activated. The com-mencement of injection is controlled withthis programme on the basis of a storedinjection map.In addition, the quantity of fuel injected isreduced.

SP 16-11

Nozzle holder


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Return-flow restrictor

Highlights

The return-flow restrictor is located in the deliveryvalve of the injection pump which controls the flowin the injection pipe to the pump. The purpose of thereturn-flow restrictor is to prevent fuel dripping outsubsequently at the injection nozzle and the forma-tion of vapour bubbles in the injection pipe.

Valve plate

Compression

spring

Restrictor drilling

Return flow

During the return flow the force ofthe compression spring acts on thevalve plate and shuts off the mainpassage. The fuel flows onlythrough the restrictor drilling. Thiscushions any pressure wave whichmay exist.

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Valve plate

Compression

spring

SP 16-14

Fuel delivery

During fuel delivery the valve plate islifted off by the fuel pressure and therestrictor drilling is inoperative. Thefuel flows through the main passage.

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Delivery valve


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Vacuum pump

The vacuum pump which is required additionally on a die-

sel engine for producing vacuum is driven directly by thecamshaft. The vacuum pump consists of a rotor and avane. The vane is made of plastic and is able to move on itsmountings.

Expansion of space

During a rotary movement of the rotor, the vane is pushedto the outside and the space is expanded. The space is fil-led with air, as a result of which a vacuum is produced atthe air inlet. The vacuum which is produced in the pump is

used by the brake servo unit and the EGR valve.

Vane

Rotor

Air inlet

(Vacuum connection

)

SP 16-16

Contraction of space

As the rotor and the vane continue to rotate, the space

produced again contracts. As a result of this, the inductedair is compressed and blown off through the air outlet tothe cylinder head. At the same time, a space is producedagain at the top.

Air outlet

VaneRotor

SP 16-17

SP 16-15


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System Architecture

The 1.9-ltr. TDI engine is equipped with an electronic engine control unit. All the control

systems of the engine are combined in the control unit.As a result of the electronic injected quantity control, it is possible to correct the quantity offuel injected in line with the air pressure, the air temperature, the coolant temperature andthe fuel temperature. In the past, using mechanical control systems, it was not possible toallow for these parameters.Use of the electronic control unit makes it possible to achieve demanding targets such asreducing fuel consumption and pollutant emissions while at the same time ensuring a highdegree of accuracy over long periods. At the same time, the system is able to react morerapidly to stresses which may occur at higher engine outputs.

N108

N109N146

G70G71 + G72

N18

AGR

G62

G28

G81 G149

N75 G80

Q6

VP


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Servicing of the engine is greatly simpli-fied and the number of operations invol-ved at an inspection is reduced as aresult of eliminating the need to set theinjection pump.

Any faults which occur can be rapidlydetected and easily rectified as a resultof the complete self-diagnosis system.

Control functions

Injected quantity control Calculating the quantity of fuel to be injected from

performance curves Start quantity control Fuel shut-off on overrun Limiting quantity injected if black exhaust is produ-

ced Controlling idling speed and limit speed of engine Controlling quantity injected for enhancing smooth

running

Injection advance Basic setting of commencement of injection accor-

ding to injection maps Correction in warming-up phase

Controlling the moment of injection when enginestarted

EGR exhaust gas recirculation Map-controlled

Charge pressure limit Map control of charge pressure Controlled in line with operating state

Auxiliary heater for coolant Map control of heating

Glow period Map monitoring of glow period After-glowing

Self-diagnosis Monitoring of sensors and actuators Fault memory Basic setting Diagnosis of actuators Emergency functions Reading results of measurements with fault reader

V.A.G 1551 or vehicle system tester V.A.G 1552.

SP 16-18

Note:You will find an explanation of the abbre-viated designations of the components inthe chapters on sensors and actuators.

J248

J366

T16

K29

F/F47 F36 G79


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J248

G80

N108N109

Q6

G71 + G72

AGR

N18

Position of Components

EGR EGR valve

G71 Intake manifold pressure sender

G72 Intake manifold temperature sender

G80 Needle lift sender

J248 EDC control unit

N18 EGR valve

N108 Commencement of injection valve

N109 Fuel cut-off valve

Q6 Glow plugs (engine)


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N75

J360J359

G70

Q7

G28 G62

G28 Engine speed sender

G62 Coolant temperature sender

G70 Air mass meter

J359 Low heating output relay

J360 High heating output relay

N75 Charge pressure control solenoid valve

Q7 Heating elements (coolant)

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System Overview

The diesel direct injection system control unit J248 makes use of maps and characteristic curves in

order to ensure that the engine is operating optimally in terms of torque development, fuel con-sumption and emission characteristics in every operating situation.

System overview of electronic control of the TDI

Needle lift sender G80

Engine speed sender G28

Coolant temperature sender G62

Air mass meter G70

Intake manifold temperature sender G72

+ Intake manifold pressure sender G71

Brake light/brake pedal switch F/F47

Clutch pedal switch F36

Accelerator pedal position sender G79

+ Idling switch F60

+ Kickdown switch F8

Modulating piston movement sender G149

Fuel temperature sender G81

Additional signals

Sensors

Air conditioning

Terminal DF

DURC

HFLUSS

074906

461

FLOW

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MANY

PIERBUR

G>PBT

-GF/M

40


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Glow plugs (engine) Q6

Glow plug relay J52

Heating element (coolant) Q7

Low heating capacity relay J359

Heating elements (coolant) Q7

High heating capacity relay J360

EGR valve N18

Charge pressure control solenoidvalve N75

Glow period warning lamp

K29

Commencement of injection

valve N108

Additional signals

Actuators

Fuel cut-off valve N109

Engine speed signal

Fuel consumption signal

Air conditioning

Diesel direct injection sy-

stem control unit J248

with altitude sender F96

Diagnostic connection

Quantity adjuster N146

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Sensors

Shaft

Potentiometer

Spiral spring

Accelerator pedal position senderG79

The determining factor for calculating the requiredquantity of fuel to be injected is the position of theaccelerator pedal - the driver input. This is detectedby a sender. The accelerator pedal position senderG79 is a potentiometer which is installed in thepedal mounting.It is operated by means of a short cable. The poten-tiometer passes the respective angle of rotation tothe electronic control unit.A spiral spring in the sender housing produces arestoring force which provides the driver with theimpression that he is operating a mechanical acce-

lerator pedal.In addition to the potentiometer, the sender alsoaccommodates the idling switch F60 and the kick-down switch F8.

Analysis of signalThe electronic control unit calculates the quantity offuel to be injected and the commencement of injec-tion from the signal supplied by the sender. In addi-tion, these signals are used for controlling thecharge pressure and for operating the exhaust gas

recirculation.

Substitute functionIf the sender is faulty, the engine runs at a fastidling speed of about 1300 rpm.This therefore enables the customer to drive to thenearest workshop. The accelerator pedal positionsender G79 does not operate in such a case.

Self-diagnosisThe fact that the sender signal is not plausible is

stored in the electronic control unit. This signal canbe checked in function "08", Reading measuredvalue block, display group "002". The figure for theaccelerator pedal position appears in the secondfield of the display as a %.

SP 16-21

SP 16-22

6

12 8

G79F60 8/F

24 11 23

248J

4 5 1 2 3


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Note:If, in addition, no signal is supplied by theneedle lift sender, the engine stops.

Engine speed sender G28

The engine speed is one of the most important

parameters for calculating the quantity of fuel to beinjected and the commencement of injection.The inductive sender for engine speed G28 moni-tors the angle position of the crankshaft. The sen-der rotor (a disc with four recesses) is mounted onthe crankshaft. The correct position is fixed by adowel pin. The distance between two successivepulses is measured in the electronic control unit.The momentary value of the position of the cranks-haft is calculated by analysing the four pulses.

SP 16-23

Analysis of signalThe signal is used for calculating the quantity offuel to be injected and the commencement of injec-tion. The signal supplied by the engine speed sen-der is analysed for performing the functions ofexhaust gas recirculation, preheating of the glowplug and the signal for the glow period warninglamp.

Substitute functionIf the engine speed sender develops a fault, theelectronic control unit switches over to the emer-gency mode.

The signal supplied by the needle lift sender G80 isused as a substitute signal. The commencement ofinjection is controlled according to the injectionmaps while charge pressure and quantity of fuelinjected are reduced. The idling speed monitor, thefuel shut-off on overrun and the air conditioning areswitched off, as a result of which engine speed isreduced slightly during brake applications. All in all,this fault is noticeable from an increase in idlingspeed.

SP 16-24

69 67

248J

1 2

G28

71

3

Self-diagnosisTwo possible causes of faults are stored in electro-nic control unit:

- Signal not plausible- No signal


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FLOW

7.18221.01

GERMANY

PIERB

URG>P

BT-GF/M40PBT-GF/M40PB

T-GF/M40

Documents

TDI DIESEL ENGINE