Curriculum Training

Curriculum Training

Diesel Injection and Engine Management Systems

Unit Injector System

Technical Service Training CG 8181/S en 12/2005 TC3043049H

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To the best of our knowledge, the illustrations, technical information, data and descriptions in this issue were correct at the time of going to print. The right to change prices, specifications, equipment and maintenance instructions at any time without notice is reserved as part of FORD policy of continuous development and improvement for the benefit of our customers. No part of this publication may be reproduced, stored in a data processing system or transmitted in any form, electronic, mechanical, photocopy, photocopy, recording, translation or by any other means without prior permission of Ford-Werke Ford-Werke GmbH. No liability can be accepted for any inaccuracies in this publication, although every possible care has been taken to make it as complete and accurate as possible.















Preface

More stringent exhaust and noise emission standards and requirements requir ements with regard to low fuel consumption continue to place new demands on the fuel injection system of diesel engines. To ensure these requirements are met, the injection system has to inject the fuel into the combustion chamber at high pressure to achieve good mixture preparation and, in the process, must also meter the injected fuel quantity as accurately as possible. Since the introduction of the 1.8L Endura-DI in the Ford Focus, the then still partially mechanical control of the diesel fuel injection systems has progressively been superseded by systems with fully-electronic control. The unit injector system is characterized by high precision in terms of injected fuel-quantity and start of injection control and by high fuel pressures. Completion of the E-learning program "Diesel Fuel Injection and Engine Management System" is a prerequisite for the study of this Student Information. This Student Information is divided into lessons. It has been designed as a self-learning tool in accordance with the new Ford training concept. Please remember that our training literature has been prepared for FORD TRAINING PURPOSES PURPOSES only. Repairs and adjustments MUST always be carried out according to the instructions and specifications in the workshop literature. Please make full use of the training offered by Ford Technical Technical Training Courses to gain extensive knowledge of both theory and practice.















Table of Contents

PAGE

Preface.............................................................................................................................. Preface ..............................................................................................................................

1

Lesson 1 – General Information Information Objectives................................... Objectives....................................................................... ......................................................................... ......................................................................... ........................................ ....

5

Introduction .............................................. ...................................................................... ................................................ ................................................ ................................................. ............................................... ......................

6

Injection characteristics........................ characteristics................................................ ................................................ ................................................ ................................................. ................................................. .......................... ..

7

Test questions................................... questions........................................................................ ......................................................................... ...................................................................... ..................................

9

Lesson 2 – Unit Injector Fuel Injection System Objectives................................... Objectives....................................................................... ......................................................................... ......................................................................... ........................................ ....

11

Overview...................... Overview.............................................. ................................................ ................................................ ................................................ ................................................. ................................................. .......................... ..

12

Characteristics...................... Characteristics.............................................. ................................................ ................................................ ................................................ ................................................ ........................................... ...................

13

Special features........................ features................................................ ................................................ ................................................ ................................................. ................................................. ...................................... ..............

13

PC M ............................................. ..................................................................... ................................................ ................................................ ................................................ ................................................. ................................... ..........

13

Signal processing in the PCM .............................................. ...................................................................... ................................................ ................................................. ........................................... ..................

16

Glow plug control........................ control ................................................ ................................................ ................................................ ................................................. ................................................. .................................. ..........

18

Sensors.................................. Sensors....................................................................... ......................................................................... ........................................................................ .............................................. ..........

19

MAF sensor...................... sensor.............................................. ................................................ ................................................ ................................................ ................................................. ............................................... ......................

19

CMP sensor...................... sensor.............................................. ................................................ ................................................ ................................................ ................................................. ............................................... ......................

19

CKP sensor....................... sensor............................................... ................................................ ................................................ ................................................ ................................................. ............................................... ......................

20

ECT sensor....................... sensor............................................... ................................................ ................................................ ................................................ ................................................. ............................................... ......................

21

AP P .............................................. ...................................................................... ................................................ ................................................ ................................................. ................................................. .................................. ..........

22

MAPT sensor....................... sensor............................................... ................................................ ................................................ ................................................ ................................................. ........................................... ..................

22















Table of Contents

Auxiliary input signals....................... signals ............................................... ................................................. ................................................. ................................................ ................................................ ............................ ....

24

Actuators.................................. Actuators...................................................................... ........................................................................ ......................................................................... ........................................... ......

25

Unit injector solenoid valve....................... valve ............................................... ................................................. ................................................. ................................................ ............................................ ....................

25

Boost control solenoid valve .............................................. ....................................................................... ................................................. ................................................ ............................................ ....................

28

EGR solenoid valve........................ valve ................................................ ................................................. ................................................. ................................................ ................................................ ................................ ........

28

Intake manifold flap solenoid valve....................... valve ................................................ ................................................. ................................................ ................................................ ................................ ........

29

Glow plug warning indicator .............................................. ...................................................................... ................................................ ................................................ ............................................ ....................

29

Electric fuel lift pump........................ pump ................................................ ................................................. ................................................. ................................................ ................................................ ............................ ....

30

Auxiliary output signals ............................................. ...................................................................... ................................................. ................................................ ................................................ ............................ ....

30

Strategies.................................. Strategies...................................................................... ........................................................................ ......................................................................... ........................................... ......

31

Fuel metering calculations..................... calculations ............................................. ................................................. ................................................. ................................................ ................................................ ........................

31

Judder damper........................ damper................................................ ................................................. ................................................. ................................................ ................................................ ........................................ ................

31

Idle speed control....................... control ............................................... ................................................. ................................................. ................................................ ................................................ .................................... ............

32

Smooth-running control (cylinder balancing) ................................................. ......................................................................... ................................................ ........................................ ................

32

Control of the fuel limitation quantity ............................................... ........................................................................ ................................................. ................................................ ............................ ....

33

Switching off the engine ................................................ ......................................................................... ................................................. ................................................ ................................................ ........................

33

EGR system........................ system................................................ ................................................. ................................................. ................................................ ................................................ ............................................ ....................

33

Boost pressure control........................ control ................................................ ................................................. ................................................. ................................................ ................................................ ............................ ....

35

Data exchange........................ exchange................................................ ................................................. ................................................. ................................................ ................................................ ........................................ ................

36

Fuel system..................................... system......................................................................... ........................................................................ ......................................................................... .....................................

37

Overview........................ Overview................................................ ................................................ ................................................. ................................................. ................................................ ................................................ ........................

37

Location and components of the unit injector ................................................. ......................................................................... ................................................ ........................................ ................

39

Drive....................... Drive............................................... ................................................ ................................................ ................................................. ................................................. ................................................ ................................ ........

39

Injection sequence - unit injector

40















Table of Contents

Injection process...................... process.............................................. ................................................ ................................................ ................................................. ................................................. ...................................... ..............

43

Control of the injection process....................... process ............................................... ................................................ ................................................ ................................................. ....................................... ..............

45

Electric fuel lift pump...................... pump .............................................. ................................................ ................................................ ................................................. ................................................. .............................. ......

47

Mechanical fuel pump...................... pump .............................................. ................................................ ................................................ ................................................. ................................................. .............................. ......

47

Fuel rail........................ rail................................................ ................................................ ................................................ ................................................ ................................................. ................................................. .......................... ..

49

Test questions................................... questions........................................................................ ......................................................................... ...................................................................... ..................................

52

Answers to the test questions......................................................................................... questions.........................................................................................

54

List of Abbreviations....................................................................................................... Abbreviations.......................................................................................................

55

















Lesson 1 – General Information

On completing this lesson, you will be able to: •

expla explain in why why the unit unit injec injector tor system system is used. used.

•

state state the the reason reasonss for for the use of pre-in pre-injec jectio tion. n.

•

expla explain in what what effec effectt pre-in pre-injec jectio tion n has on on combu combusti stion. on.

Objectives


















Introduction

2 1

E64972

1

Unit injector

Increasingly higher demands are being placed on modern diesel engines. Today, Today, the focus is not alone on exhaust emissions but also on increasing environmental awareness and the demand for ever better fuel economy and enhanced driving comfort.

2

PCM (Powertrain Control Module)

Demands for better driving comfort also influence the requirements placed on today's diesel engines. In particular, the importance of noise and exhaust emissions continues to increase. This leads to increased demands being placed on the injection system and its control, e. g.:

This requires the use of complex injection systems, high injection pressures and precise fuel metering by fully electronically-controlled systems. The high injection pressures convert the fuel, via the fuel injector nozzle, into tiny droplets, which, again thanks to the high pressure, can then be optimally

– high high inje injecti ction on pres pressu sure res, s, – shapin shaping g of injectio injection n timing timing charact characteri eristi stics, cs, – prepre-in inje ject ctio ion n, – injected injected fuel fuel quantity quantity,, start start of injecti injection on and and boost boost pressure values adapted to every operating condition,


















system has a large range of The Bosch unit injector system has

Injection characteristics

features to meet these demands. The unit injectors can precisely inject the correct fuel quantity individually into each cylinder at the correct time under very high pressures. They replace the injector injec tor holder assembly and common injection pump used in conventional conventional injection systems. High-pressure lines are dispensed with. This has a positive effect on injection characteristics. With this type of diesel injection and engine management system, the driver has no direct influence

As already mentioned at the beginning of the lesson, the exhaust emissions and fuel consumption of consumption of an engine are of great significance. These factors can only be minimized through precise operation of the injection system and comprehensive engine management strategies. Consequently, Consequently, the following requirements are made of the unit injector system: •

The inje injectio ction n timing timing must must be be exact. exact. Even Even small small

on the injected fuel quantity as the accelerator pedal has

variations have a significant effect on fuel

no mechanical connection to the unit injector, for

consumption, exhaust emissions and combustion

example. Here, the injected fuel quantity is determined

noise.

by a range of variables. These include: – driver driver demand (accelerator (accelerator pedal position), position), – oper operat atin ing g stat state, e, – engi engine ne temp temper eratu ature re,,

•

Injection Injection must be terminated terminated reliably reliably.. Calcula Calculation tion of the injected quantity and the injection timing are precisely adapted to the mechanical components of the injection system. Uncontrolled fuel dribble (caused for example by a defective fuel injector

– effec effects ts on on exha exhaust ust emissi emissions ons,,

nozzle) results in increased exhaust emissions and

– protection protection against against engine engine and transmissi transmission on damage, damage,

increased fuel consumption.

– faul faults ts in the the sys syste tem. m. Using these parameters, the injected fuel quantity is calculated in the PCM and PCM and fuel injection timing can be varied. The fuel is metered fully electronically via solenoid valves controlled by the PCM which PCM which are located directly in the unit injectors.

Simple main injection: Needle lift of fuel injector nozzle and pressure pressure curve in the cylinder without pre-injection


















1

Combustion pressure in the cylinder

1

Combustion pressure in the cylinder

2

Needle lift

2

Needle lift

3

TDC (Top Dead Center)

3

TDC

4

Needle lift during main injection

4

Needle lift during pre-injection

5

Crank angle

5

Needle lift during main injection

6

Crank angle

In the case of diesel engines with a distributor type fuel injection pump (for pump (for example in the Ford Transit),

In the case of pre-injection, a small amount of fuel is

the fuel injection on the pump-side is via simple main

injected into the cylinder prior to the main injection.

injection.

Through pre-injection, a gradual pressure increase is

In the pressure curve, the combustion pressure increases

achieved in the combustion chamber, which in turn

only slightly in the phase BTDC (Before Top Dead

results in improved combustion quality. quality.

Center), Center), corresponding to compression, but increases very sharply at the start of combustion. The steep pressure rise intensifies the combustion noise.

The small, pre-injected fuel quantity is ignited and heats up the upper part of the cylinder, thereby bringing it into an optimum temperature range (pre-conditioning of the combustion chamber).

Pre-injection

This means that the main injection mixture will ignite

Needle lift of fuel injector nozzle and pressure curve in the cylinder with pre-injection

more quickly and the rise in temperature will be less abrupt as a result. Because there is a smaller rise in temperature, combustion pressure is also reduced, which in turn substantially reduces combustion noise. Advantage: •

1

Contin Continuou uouss buildbuild-up up of comb combust ustion ion press pressure ure,, resulting in reduced combustion noise,

3

•

Reduct Reduction ion of of nitrog nitrogen en oxide oxidess in the exha exhaust ust gas. gas.


















Test questions

Tick the correct answer or fill in the gaps.

1.

What is the advantage of the unit injector system? a. The high-pres high-pressure sure lines lines between between the individual individual pumps pumps and fuel injector injector nozzles nozzles are not longer longer than 120 mm, minimizing pressure fluctuations. b. Combustio Combustion n noise noise is minimized minimized throug through h the indirect indirect injectio injection. n. c. The unit injectors injectors can can simultaneous simultaneously ly inject the correct correct quantity quantity of fuel fuel at the correct time into into each cylinder cylinder individually at the lowest possible pressure. d. The unit injectors injectors can can precisely precisely inject the correct correct quantity quantity of fuel at the correct correct time into each cylind cylinder er individually under very high pressures.

2.

What does pre-injection mean? a. Fuel is injected injected into the the combustion combustion chamber chamber during during the intake intake strok stroke. e. b. Injection Injection occurs occurs at the start start of the compres compression sion strok stroke. e. c. A small small amount amount of fuel is is injected injected into the cylinder cylinder prior prior to the the main injectio injection. n. d. A small amount amount of additive additive is injected injected into the cylinder cylinder prior prior to the main injection injection in order order to increase increase the combustion pressure.

3.

What is the effect of pre-injection? a. Pre-injecti Pre-injection on only only results results in a reduction reduction of of fuel consumptio consumption. n. b. Pre-injecti Pre-injection on results results in a gradual gradual increase increase in the combu combustion stion pressur pressure. e. c. Pilot injection results in an abrupt build-up of combustion combustion pressure pressure and therefore therefore reduced reduced combustion combustion noise. d. Pre-injection Pre-injection results in an abrupt build-up build-up of combustion combustion pressure pressure and therefore therefore increased increased combustion combustion noise. noise.



















Notes



















Lesson 2 – Unit Injector Fuel Injection System

Objectives

On completing this lesson, you will be able to: •

name name the compon component entss of the the engi engine ne mana managem gement ent system system..

•

describe how the PCM works PCM works and be familiar with the t he integrated diagnostics.

•

explain explain the function function of the the individual individual engine engine management management compone components nts and identify identify the the effects effects of component component faults.

•

name name the the com compo pone nent ntss of the the fuel fuel sys system tem..

•

name the the components components of of the low low and high-pr high-pressu essure re systems systems and and be familiar familiar with with their their function. function.

•

describe describe the the component componentss of the the high-pres high-pressure sure system system and be familiar familiar with with their their function. function.

•

put the knowl knowledge edge acquired acquired into into practice practice in diagnosti diagnosticc operations operations and and thus draw draw conclusions conclusions regar regarding ding possibl possiblee malfunctions of individual components.




















Overview

17

7 2

1 18 8

9

19

10

20




















1

PCM

13 CPP (Clutch Pedal Position) switch Position) switch

2

BARO (Barometric pressure) sensor pressure) sensor

14 BPP (Brake Pedal Position) switch Position) switch and stoplamp

3

DLC (Data Link Connector)

4

CAN (Controller Area Network)

15 Fuel temperature sensor

5

ABS (Anti-lock brake system) module system) module

16 Auxiliary input signals *

6

Transmission control module

17 Glow plug relay, glow plugs

7

MAF (Mass Air Flow) sensor Flow) sensor

18 Unit injector solenoid valve

8

CKP (Crankshaft Position) sensor Position) sensor

19 Glow plug warning indicator

9

CMP (Camshaft Position) sensor Position) sensor

20 EGR solenoid EGR solenoid valve

10 APP (Accelerator Pedal Position) sensor Position) sensor

21 Wastegate control valve

11 ECT (Engine Coolant Temperature) Temperature) sensor sensor

22 Intake manifold flap solenoid valve

12 MAPT (Manifold Absolute Pressure and

23 Auxiliary output signals **

Temperature) sensor Temperature) sensor

* Auxiliary input signals •

VSS (Vehicle Speed Sensor) (older Sensor) (older vehicles; newer vehicles receive the vehicle speed signal via CAN) CAN)

•

switch

Air condit condition ioning ing compre compresso ssorr readi readines nesss

** Auxiliary output signals

24 Fuel lift pump

Special features Because high-pressure lines are dispensed with, significantly higher fuel pressures (up to 2050 bar) are achieved than is the case with distributor-type distributor-type injection




















The PCM is PCM is the main component of the engine management system. It receives the electrical signals

1

Signal voltage

2

Time

from the sensors and setpoint transmitters, evaluates them and calculates the actuation signals for the

signals to the The microprocessor transmits output signals to

actuators (for example unit injectors, wastegate control

actuators via actuators via specific output stages. The output signals

solenoid valve, EGR solenoid EGR solenoid valve, etc.) from them.

for the actuators can also have different forms:

The control program (the software) is stored in a memory. memory. The execution of the program is carried out by a microprocessor. microprocessor. In addition to the actuators, there are also sensors which form the interface between the vehicle and the PCM as PCM as a processing unit. The sensors, actuators and the power supply are connected to the PCM via PCM via two four-pin connectors.

– Switching Switching signal signalss (switch (switch actuato actuators rs on and off, off, such such as the A/C (air conditioning) clutch. – PWM (Pulse Width Modulation) signals. Modulation) signals. PWM signals are square-wave signals with a constant frequency, but a variable variable activation time time.. Using these signals, e.g. electro-pneumatic transducers can be actuated at any location (for example the wastegate control solenoid valve or EGR solenoid EGR solenoid valve). The high-performance components for direct actuation

Input signals from signals from the sensors can have different forms:

of the actuators are integrated in the PCM in PCM in such a

– analog analog input input sign signals als (for (for examp example le ECT, ECT, MAPT), MAPT),

manner that very good heat dissipation to the housing

– digita digitall input input sign signals als (for (for examp example le CMP sensor). CMP sensor).

is ensured.

As the microprocessor of the PCM can PCM can only process digital signals, the analog input signals must first be converted. converted. This is done internally in the PCM in PCM in an

Integrated diagnosis In the case of sensor monitoring, monitoring, the integrated






















Fault handling: If handling: If there are deviations from a

BARO sensor BARO sensor

permissible set value for a sensor, the PCM switches PCM switches to a default value. This process is used, for example, for

There is a BARO sensor BARO sensor integrated into the PCM. PCM. The

the following input signals:

BARO sensor BARO sensor registers the atmospheric pressure and

– ECT, ECT, IAT (Intake Air Temperature), Temperature), – MAP (Manifold Absolute Pressure), Pressure) , BARO, BARO, – MAF. MAF. For some driving functions with higher priority (for example APP sensor), APP sensor), there are substitute functions which, for example, allow the vehicle to continue to be driven to the next Authorized Ford Dealer.

influences the boost pressure control and torque limitation. At high altitudes, the injected fuel quantity is reduced in order to prevent turbocharger overspeed and excessive smoke emissions.






















Signal processing in the PCM

17

1 5

6

7

8 2

9

10

16






















The microprocessor is the main component componen t of the PCM. PCM. All the open and closed loop control calculations for all the functional sequences of the system are performed here.

Application-Specific Application-Specific Integrated Circuit (ASIC) Because the engine management system has continuously become more complex, the microprocessor

The input variables are provided by the sensor signals.

capacity is no longer sufficient in order to perform all

These are plausibility-checked in the microprocessor.

the tasks required.

The output signals for the actuators are calculated with the aid of the program as well as the characteristic curves and maps.

For this reason, the PCM is PCM is equipped with an application-specific integrated circuit (ASIC). This integrated circuit contains, for example, additional RAM as well as inputs and outputs. Moreover, the ASIC can

Program memory

generate and output PWM signals. PWM signals.

The microprocessor requires a program, which is stored

Monitoring module






















Glow plug control

Postheating is carried out up to an engine speed of around 2500 rpm. When 2500 rpm is exceeded, the postheating phase is terminated. The service life of the

2

1

3

glow plugs is increased as a result.

Effects in case of faults 4

Longer start-up at low ambient temperatures

6

Loud combustion noise after engine starting 5 E65253

1

CKP sensor CKP sensor

2

PCM

3

Glow plugs

Rough running engine






















MAF sensor MAF sensor

Sensors

This MAF sensor MAF sensor is able to register the mass air flow extremely precisely as it detects detec ts return flow in the intake

Location

port. Return flow is caused by the opening and closing action of the intake valves on the engine.

1 2

The MAF sensor MAF sensor with return flow detection detects return flow of the mass air and takes this into account in its signals to the engine control module. Consequently, Consequently, a very precise measurement of the mass air is achieved. The measured values are used by the engine control module for calculating the injected fuel quantity and the quantity of recirculated exhaust gas.

4

3























Sensors


Location

Effects in case of faults

Located beneath the timing cover on the cylinder head

While the engine is running, signal failure has no influence on engine running. The PCM uses PCM uses the CKP

Task / function

sensor signal to start the engine. The engine, however however starts with a delay. delay.

After the engine is started, the PCM actuates PCM actuates the unit
























A

Sensors























Sensors




In the event of a signal failure, the PCM uses PCM uses the fuel

In the event of a signal failure, the PCM cannot PCM cannot detect

temperature sensor value as a substitute value.

the accelerator pedal position. In order to make it possible to drive to the next workshop, the engine

APP

continues to run at a higher idle speed.
























Temperature sensor: – The temperature temperature sensor sensor signal signal is is require required d by the PCM as PCM as a correction value for calculating the boost pressure. The influence of the temperature on the density of the charge air is thus taken into account.

Sensors

Task / function The fuel temperature sensor provides the fuel temperature signal to the PCM. PCM. The PCM needs PCM needs to know the density of the fuel in order to take into account the density at the various


temperatures when calculating the fuel injection timing























Sensors


Task / function

Air conditioning compressor readiness

Stoplamp and BPP switches:

The PCM receives PCM receives a signal that the air conditioning has

– The The sto stopl plam amps ps on and and BPP switches BPP switches signal to the

been switched on from the air ai r conditioning switch. It

PCM that PCM that the brake is operated. – For For safe safety ty rea reaso sons ns,, the the PCM reduces PCM reduces engine power when the brake is operated, in case a fault occurs in

can then raise the engine idle speed before the air conditioning compressor is switched in order to prevent a sudden drop in engine speed during compressor


























Actuators

























Actuators



























Actuators

























Actuators



























Actuators





































































































































































































































































































































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