AUTOMOTIVE TECHNOLOGY.pdf

Engine TCU Meter
ECU Combination

High Speed CAN Bus 500kbps

ABS- BCM
ECU

1.0.16.5 CAN-Bus Voltage Differential

1 0 1
V 2.0V
CAN high
5 Dominant bit CAN low
4
3 Recessive bit
2
1

0 Recessive bit

1.0.16.6 CAN Bus Network Topology for INSPIRA

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1.0.16.7 CAN High and Low Voltage and Signals

1.0.17 Local Interconnect Network (LIN)

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LIN stands for Local Interconnect Network (LIN Consortium). Local
Interconnect means that all control units are located within a limited structural space.
This is also referred to as "Local Sub-System". The LIN bus system is a single-wire bus.
The system permits data exchange between one LIN master control unit and up to 16

LIN slave control units with maximum of 20 Kbps baud rate speed.

LIN Data CAN Data Bus
Bus

1.0.17.1 Example of LIN application on PROTON Prévè

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ABCM Rain Light Reverse
Sensor Parking Assist

Reverse
Parking
Assist

Figure 1.0.17.1.1 Example of LIN application on PROTON Prévè

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Figure 1.0.17.1.2 Example of LIN Topology on PROTON Prévè
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1.0.17.2 Example of LIN Application on PROTON PREVE
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1.0.17.3 Example of LIN Voltage Signal on PROTON PREVE
Figure 1.0.17.3 3 Example of LIN Voltage Signal on PROTON Prévè
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CHAPTER 2

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AIR INDUCTION SYSTEM

2.0 What is air induction system and how it works?

 The function of the air intake system is to allow air to reach your car engine. Oxygen
in the air is one of the necessary ingredients for the engine combustion process. A
good air intake system allows flow of clean and continuous air into the engine,
thereby achieving more power and better mileage for your car.

 A modern automobile air intake system has three main parts: air filter, mass flow
sensor and throttle body. Located directly behind the front grille, the air intake system
draws air through a long plastic tube going into the air filter housing, which will be
mixed with the car fuel. Only then will the air be sent to the intake manifold that
supplies the fuel/air mixt100ure to the engine cylinders.

1. Air Induction System with Emissions Control.
 Visteon's Air Induction System with Emissions Control is part of a total system
solution that can help automotive manufacturers reduce evaporative emissions. This
advanced system uses a hydrocarbon trap that prevents harmful emissions from
entering the atmosphere. Visteon engineers apply automotive intellect to develop a
variety of patented hydrocarbon traps to provide customers with the best solution to
their emissions challenge.

 Visteon Corporation has been an industry leader in the development and
implementation of Evaporative Emissions controls in the air induction system.
Visteon was first to market the duct-based hydrocarbon trap in 2003, and is the only
supplier who offers foam-based hydrocarbon traps. The patented Visteon Long Life
Filtration System is a filter-based solution that is accepted for use on Partial Zero
Emissions

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2.0.2 How it Works?

 When the engine is off, a hydrocarbon trap captures emissions that exit the engine
using chemical adsorption. During engine operation, these adsorbed vapors are
returned to the engine. Also while the engine is operating, the system sends
filtered air to the engine and provides noise control with minimal power loss.

1. Flexible Packaging.
 The Visteon Air Induction System with Emissions Control provides a great deal of
flexibility to the vehicle designer because the hydrocarbon trap can be
incorporated into the existing air induction system. The hydrocarbon trap can be
placed in the air filter, air cleaner box, clean air ducts, resonators or Integrated Air
Fuel Module plenum spaces. The benefits of this flexibility include:
 Selection – Can choose the best type and size of hydrocarbon trap.
I. Duct-Based Monolith – Delivers high efficiency in a small package space
II. Air-Cleaner Based – Easily retrofitted into existing designs
III. Filter-Based – Integrated into the multi-layer foam of Visteon's Long Life
Filter
IV. System Security – Can be designed as a tamper-proof, non-consumer
serviceable system.

 Scalability – Can support four-, six-, eight- or ten-cylinder applications. One common
air induction system geometry can be used in vehicles with and without the
hydrocarbon trap.

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2.0.3 The main parts of Air Induction System.

2.0.3.1 Intake Manifold.

• The Intake Manifold is attached to the cylinder head. Its construction and design depends
on its application. It is normally made of an aluminum alloy.

• On carbureted engines, the Intake Manifold supports or houses the carburetor. While on
EFI engines, it can house or support a throttle body.

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2.0.3.2 Throttle Body/Carburetor.

 The Intake Manifold can accommodate a carburetor or a Throttle Body Injection unit
as illustrated. In either case, the mixing of the air and fuel is done at the manifold
base.

 The butterfly shaft connected to the throttle cable controls the airflow through the
unit.

2.0.3.3 Multi-Point Throttle Body
 In multi-point EFI systems, a Throttle Body is attached to the Intake Manifold. While
the butterfly shaft is attached the throttle cable, it also has a Throttle Position Sensor
(TPS) attached to it as well.
 The TPS signals the ECU of the throttle opening position so that it can complete its
fuel requirement calculations.

2.0.3.4 The Air Induction Component
 The air induction components consist of an air cleaner and housing, solid and flexible-
duct tubing and connectors.
 The Air Induction System draws in ambient air from the environment. The inlet
opening may be located at various positions under the hood.

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2.0.3.5 Air Cleaner

 The air cleaner filters the incoming air. The air cleaner element may be manufactured
from pleated paper, oil impregnated cloth or felt.

 Another function of the air cleaner is to muffle the resonation ( dampen the noise) of
the swirling incoming air.

 The location of the air cleaner is dependent on the available space and the hood

design.
2.0.3.6 Ducting

 The ducting can be made of hardened plastic with flexible rubber couplings to absorb
engine movement. These are usually secured in place by metal worm drive clamps.

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2.0.3.7 Mass Flow Sensor

 A mass air flow sensor is used to find out the mass of air entering a fuel-injected
internal combustion engine. From mass flow sensor, then, it goes to the throttle body.

 There are two common types of mass airflow sensors in use on automotive engines.
They are the vane meter and the hot wire mass airflow sensors.The vane type has a
flap that is pushed by the incoming air. The more air coming in, the more the flap is
pushed backed. There is also a second vane behind the main one that fits into a closed
camber that dampens the movement of the vane giving a more accurate measurement.

 The hot wire uses a series of wires strung in the air stream. The electrical resistance of
the wire increases as the wire's temperature increases, which limits electrical current
flowing through the circuit. When air flows past the wire, it cools it, decreasing its
resistance, which in turn allows more current to flow through the circuit.

 However, as more current flows, the wire's temperature increases until the resistance

reaches equilibrium again.

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2.0.3.8 Karman Vortex Sensor

 A Karman Vortex Sensor works by setting up a laminar air stream. The air stream is
disrupted by a vertical bow in the sensor. This causes a wake in the air stream and
subsequently the wake will collapse repeatedly and cause Karman vortexes. The
frequency of the resulting air pressure oscillation is proportional to the air velocity.

 These vortexes can either be read directly as a pressure pulse against a sensor, or they
can be made to collide with a mirror which will then interrupt or transmit a reflected
light beam to generate the pulses in response to the vortexes. The first type can only
be used in pull thru air (prior to a turbo- or supercharger), while the second type could
theoretically be used push or pull thru air (before or after a forced induction
application like the previously mentioned super- or turbocharger). Instead of
outputting a constant voltage modified by a resistance factor, this type of MAF
outputs a frequency which must then be interpreted by the ECU. This type of MAF
can be found on Mitsubishi Lancers/EVOs, all DSMs (Mitsubishi Eclipse, Eagle
Talon, Plymouth Laser) and some models from Toyota and Lexus.

2.0.3.9 Cold Air Intake
 A cold air intake is used to bring cooler air into a car's engine to increase engine
power and efficiency. The most efficient intake systems utilise an air box which is
sized to complement the engine and will extend the power band of the engine. The
intake snorkel or the opening for the intake air to enter the system must be large
enough to ensure that sufficient air is available to the engine under all conditions from
idle to full throttle.

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2.0.4 Diesel Induction Systems

 Diesel engines draw in air only. Speed and power is controlled by the amount of fuel
injected at the end of the compression stroke. 2-stroke diesels use a blower
for induction and to improve scavenging.

 The two main components of the 4-stroke intake system are the air cleaner and the
intake manifold.

 But in a diesel engine, fuel is delivered separately and the intake system carries air
only.

 Also, since the diesel engine doesn’t have a carburetor, it has no throttle. Some diesels
use a pneumatic governor with a butterfly valve at the entrance to the inlet manifold.

 Diesel engines often have more than one air cleaner.
 Let’s look at the intake system for a 2-stroke diesel engine. There is only a very short

time at the end of its power stroke to scavenge the exhaust gases and refill the
cylinder with air. To achieve this in the available time, 2-stroke diesels use an engine-
driven air pump, usually called a blower. It pressurizes the air so that when the inlet
ports open, air from the blower can enter the cylinder and help scavenge the exhaust
gases.
 Some 2-stroke diesel engines use a turbocharger which feeds air under pressure to the
blower.
 The intake system of the diesel engine can be used to increase engine output. This can
be done by increasing volumetric efficiency, that is, by increasing the amount of air-
fuel mixture burnt in the cylinders.
 In diesel injection systems, this partly occurs automatically because of the increased
efficiency of fuel injection.
 Output can also be improved by using large, free-flowing intake manifolds, and by
increasing the number or the size of inlet valves per cylinder to admit more charge
into the combustion chamber.

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CHAPTER 3

64

SUB ENGINE MANAGEMENT SYSTEM-FORCE INDUCTION

1. Introduction

Adjustable Cylinder Management

 Adjustable Cylinder Management or VCM (Variable Cylinder Management) is the
term used by Honda for adjustable displacement technology.

 It uses the i-VTEC system to disable inline cylinders in certain driving conditions
(e.g., driving on the highway) to save fuel.
.

 Honda's VCM technology using overhead camshafts compared Multiple
Displacement System by DaimlerChrysler and Active Fuel Management by General
Motors that use push rod engine.

 The system uses a solenoid to release the cam follower on a line of rocker arms,
respectively, so that the follower floats freely while the valve springs ensure that the
valve is closed.

 Throttle Wired Pacemaker allows the engine management computer to smooth the
power delivery of the engine.

 Vehicles equipped with VCM also include indicators of "ECO" on the dashboard
according to VCM system operation. Vehicles equipped with VCM also include
Active Noise Cancellation system (ANC) and Active Control Engine Installation
Honda (ACM).

 Both the ANC and ACM systems are correlated to eliminate noise and vibration
caused by the disabling of the cylinder.

 ANC system using audio speakers cancels noise through phase noise.

1. Horsepower

 Horsepower (hp or HP) is the name of several non-metric measurement unit of power.
In scientific usage, the term "horsepower" is rarely used because of the different
definitions and existing SI unit for the power watt (W). 'HP' is gradually replaced by
kW (kilowatt) and MW (megawatts).

 There are two main factors to be considered while assessing the size of the
"horsepower":

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 Definition of horsepower itself is not consistent
 The standards for the measurement of various horsepower.

 Mechanical Horsepower

The term "horsepower" was used by the engineer James Watt (1736 - 1819) in 1782
while looking for ways to improve the performance of the steam engine. It happened
while using a small horse to transport coal out of the coal mines. He got the idea of
defining power by comparison with the number of animals to do the job.

 Electrical Horsepower

Electrical horsepower is used in electrical engineering to measure the power of
electrical machinery and is exactly defined as 746 W at 100% efficiency. The electric
motor may not run at 100% efficiency. Name plate on the electric motor shows motor
output power and not the power it needs.

Sensors and Actuators

Basic and Physics such as: classification of effects, physical effects, theory of
measurement, sensor modeling, measurement standards, measurement error, units and
constants, time and frequency measurement. Paper Modelling whether to bring a new
modeling technique to the field and / or supported by the experimental results.

Fuel Injections System
To overcome the problem of pollution and the legal production of fuel

efficiency, fuel system used in modern cars has been changed considerably over the
past few years. Fuel injection system has been around since the 1950s, and electronic
fuel injection is widely used in Europe since 1980. Modern cars, sold in the United
States, have a system of fuel injection fire.

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3.0.2 Types of Fuel Injection

Single-Point or Throttle Body Injection (TBI)

 The type of fuel injection earliest and most simple, the facts simply replace the
carburettor with one or two nozzles in the fuel injector throttle body, the engine air
inlet throat. For some manufacturers, a single injection point is a stepping stone to a
more complex system of multi-point. Although not as precise as the system has to
follow, TBI fuel meter is better and cheaper than the carburettor and and is easier to
service.

Port or Multi-Point Fuel Injection (MPFI)

 Injection Port or Multi-point fuel injector nozzle focus areas for each cylinder just
outside the intake port, which is why the system is sometimes called the injection
port. Shooting the fuel vapours close to the intake port is to ensure that it will be
drawn into the cylinder. The main advantage is that the meter is more accurate than
TBI design, it better achieves the stoichiometric air / fuel required and improves all
related aspects.

 In addition, it virtually eliminated the possibility that the fuel will condense or
accumulate at the inlet. With TBI and carburettors, intake manifold must be
designed to let heat engine move to vaporized liquid fuel.

Sequential Fuel Injection (SFI)

 Sequential fuel injection is also known as Sequential Port Fuel Injection (SPFI) or
Timed Injection or Multi-Port Injection Type. Although basic MPFI use various
injectors, they all spray their fuel at the same time or in group. Fuel can "roam" port
for 150 milliseconds when the engine is idling.

 This may not seem like much, but it is enough of the weakness that the engineers are
addressing: Sequential Fuel Injection Injector nozzle triggers each independently. The
spark plugs spray fuel immediately before or as terbia. Intake valve seems to be a
small step, but the efficiency and emissions improvements come in very small
quantities.

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3.0.3 Direct Injection (Direct Injection)

 Injection continued to fuel injection concept about how far it can go, injecting fuel
directly into the combustion chamber passing through the valve. More common in
direct injection diesel engines began to appear in petrol engine design, sometimes
called Dig for gasoline direct injection.

 Again, fuel metering is more accurate than other injection schemes, and direct
injection give engineers more possibilities to influence exactly how combustion
occurs in the engine design cylinder. Science examines how the swirls mix fuel.

Sub-System of Engine Management System

NOS ( Nitrous Oxide System )

 Nitrous Oxide System, also known as NOS or nitrous, only refers to nitrous oxide gas
injection system in a vehicle race as oxidizing agent for the purpose of obtaining a
temporary instant acceleration. Abbreviation was derived from the acronym of NOS
Nitrous Oxide Systems (NOS), by one of the pioneers who introduced Nitrous Oxide
Injection System in the automotive field.

 Nitrous oxide gas is used as the oxidizing agent to enhance engine power temporarily

to allow burning of more fuel (mainly gasoline than normal.
3.0.4 There are three types of nitrous oxide

• Dry type
 Nitrous oxide injector is mounted near the air flow sensor. When the button is
pressed, nitrous oxide injector will inject nitrous oxide gas at the air flow
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sensor to "fool" the sensor so that the ECU should supply more fuel to the
engine.
 The system is very similar to the system in the wet type but further points the
input cavity mounted injectors for each cylinder gasoline-nitrous oxide.
• Wet type
 The wet type is more widely used on carburated vehicles but vehicles using
fuel injection can also use this system. In the wet type system, a fuel injector,
which mixes gasoline with nitrous oxide gas, will be installed at the base of
the cavity input and injector will continue supplying petrol mixture of nitrous
oxide nitrous oxide until the button is released.

Advantages of NOS
Nitrous oxide system is able to increase the power and instant acceleration

easily with the push button, but to maintain the high power, nitrous oxide gas is
needed in large amounts.

Disadvantages of NOS
Normal engines installed with NOS system without any modification would

suffer serious damage because they can not handle the increase in power due to the
use of NOS. Therefore, the NOS system is not suitable for daily use and is only used
during the race.

3.0.5 Turbocharger

 The turbocharger or turbo is a gas compressor tool used for the purpose of
forced breathing on internal combustion engines. Like the supercharger,
turbocharger’s main purpose is to increase the density of the incoming air into
the engine to produce more power. However, the turbocharger consists of a
compressor driven by the turbine, which is also driven by the engine's own
exhaust gases.

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1. Components of the Turbocharger
• Compressor

 Turbo compressor systems are of the functioning radial vane compressor
forcing air into the engine and compressing at high pressure. It is connected to
the turbine via a shaft and is placed together with the turbine in the same host.

• Turbine

 Like compressors, turbines also consist of radial turbine type blades that are
connected to the compressor. It is driven by the engine's own exhaust gases
with rotational speeds as high as over 120,000 rpm. Very high turbine
rotations are required. It is supported by the special sockets lubricated by a
continuous flow of lubricant.

• "Waste gate“ Valve

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 This valve serves as an exhaust gas pressure control valve so that the exhaust
gas pressure will not cause the turbine to spin too high to damage the turbine
itself. On the set boost pressure, "waste gate" valve opens a path that bypasses
the turbine side to control the maximum rotation of the turbine.

• "Blow-off“ Valve

 This valve, in short, is a pressure relief valve that releases compressed air
pressure when the throttle is released so that the air pressure should not
damage the turbocharger unit because there is no way out.

• Cooling Medium (Intercooler)

 Cooling medium is a heat exchanger that resembles the radiator and cools
high-pressure compressed air to increase its density. However, some of the
turbocharger systems with a low boost pressure do not require a cooling
medium.

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3.0.6 Technology DVVT

 All versions of the engine - 660cc, 850cc and 1,000 cc - used by Daihatsu used DVVT
technology. This engine is widely used in vehicles such as:
a) Perodua Viva
b) Perodua myvy
c) Perodua Alza

VVT-i or Variable Valve Timing with Intelligence

3.0.6.1 Dual VVT-i

 In 1998, Dual first introduced the 3S-GE engine Altezza Rs200.
 Dual VVT-i is also found in Toyota's new generation V6 engine, the 2GR-FE 3.5

litter that first appeared in Avalon 2005.
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 Toyota UR engine (V8), GR engines (V6), AR engines (large I4), and ZR engines
(Small I4): they all use this technology.

3.0.6.2 VVT-iE

 VVT-i (Variable Valve Timing - intelligence by Electric motor) is a version of Dual
VVT electric actuators that operates to maintain intake camshaft timing. Timing is
still controlled by the hydraulic actuators using exhaust camshaft.

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7. The Average Street Engine

 The volumetric efficiency is about 75% at maximum speed or 80% at the torque peak.

 Turbocharged and supercharged engines easily achieve more than 100% volumetric
efficiency.

1. Engine Compression

 Higher compression increases the thermal efficiency of the engine because it raises
compression temperatures, resulting in hotter amd more complete combustion.
However, a higher compression can cause an increase in NOX emissions and would
require the use of high-octane gasoline with effective antiknock additives.

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8. SUPERCHARGING PRINCIPLES

 The amount of force an air-fuel charge produces when it is ignited is largely a
function of the charge density.

 Density is the mass of a substance in a given amount of space.
 An engine that uses atmospheric pressure for intake is called a naturally (normally)

aspirated engine.
 When air is pumped into the cylinder, the combustion chamber receives an increase of

air pressure known as boost and is measured in pounds per square inch (psi),
atmospheres (ATM), or bar.

 While boost pressure increases air density, friction heats air in motion and causes an

increase in temperature

1. Other Advantages of Supercharging an Engine

 It increases the air-fuel charge density to provide high-compression pressure when
power is required, but allows the engine to run on lower pressures when additional
power is not required.

 The pumped air pushes the remaining exhaust from the combustion chamber during
intake and exhaust valve overlap.

 The forced airflow and removal of hot exhaust gases lower the temperature of the
cylinder head, pistons and valves and help extend the life of the engine.

 A supercharger pressurizes air to greater than atmospheric pressure. The
pressurization above atmospheric pressure or boost can be measured in the same way
as atmospheric pressure. Atmospheric pressure drops as altitude increases, but boost
pressure remains the same.

 If a supercharger develops 12 psi (83 kPa) boost at sea level, it will develop the same

amount at a 5000-foot altitude because boost pressure is measured inside the Intake

Manifold.

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3.0.9 SUPERCHARGERS

There are two general types of superchargers:
a) Roots-type
 The roots-type supercharger is called a positive-displacement design because
all of the air that enters is forced through the unit.
b) Centrifugal supercharger
 A centrifugal supercharger is not a positive displacement pump and all of the
air that enters is not forced through the unit. Air enters a centrifugal
supercharger housing from the center and exits at the outer edges of the
compressor wheels at a much higher speed due to centrifugal force.
 The speed of the blades has to be higher than engine speed, so a smaller pulley
is used on the supercharger and the crankshaft overdrives the impeller through
an internal gear box achieving about seven times the speed of the engine.
Examples of centrifugal superchargers include Vortech and Paxton

Supercharger Boost Control
 Many factory installed superchargers, equipped with a bypass valve that allows
intake air to flow directly into the Iintake Manifold, bypassing the supercharger.

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1. The airflow is directed around the supercharger whenever any of the
Following conditions occur:

 The boost pressure, as measured by the MAP sensor, indicates that the intake
manifold pressure is reaching the predetermined boost level

 During deceleration

 Whenever reverse gear is selected.

3.0.9.2 Turbo chargers

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 The major disadvantage of a supercharger is its reliance on engine power to drive
the unit. In some installations, as much as 20% of the engine’s power is used by a
mechanical supercharger.

 The combustion heat energy lost in the engine exhaust (as much as 40- 50%) can
then be harnessed to do useful work. This is the concept of a turbocharger. In a
naturally aspirated engine, about half of the heat energy contained in the fuel goes
out to the exhaust system.

 Another 25% is lost through radiator cooling. Only about 25% is actually
converted to mechanical power.

 A turbocharger turbine looks much like a typical centrifugal pump used for
supercharging.

 As exhaust gas enters the turbocharger, it rotates the turbine blades
 The turbine wheel and compressor wheel are on the same shaft, so they rotate with

the same speed.

 Rotation of the compressor wheel draws air in through a central inlet and

centrifugal force pumps it through an outlet at the edge of the housing.
 A pair of bearings in the center housing supports the turbine and compressor

wheel shaft and is lubricated by engine oil.
 As the engine runs faster or load increases, both exhaust heat and flow increases,

causing the turbine and compressor wheels to rotate faster.
 When an engine is running at full power, the typical turbocharger rotates at speeds

between 100,000 and 150,000 RPM

3.0.10 To prevent problems, four conditions should be considered:

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 The turbocharger bearings must be constantly lubricated with clean engine oil.
Turbocharged engines should have regular oil changes at half the time or mileage
intervals specified for non-turbocharged engines.

 Dirt particles and other contamination must be kept out of the intake and exhaust
housings

 Whenever a basic engine bearing (crankshaft or camshaft) has been damaged, the
turbocharger must be flushed with clean engine oil after the bearing has been
replaced.

 If the turbocharger is damaged, the engine oil must be drained and flushed and the oil
filter must be replaced as part of the repair procedure

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3.0.10.1 A turbine wheel is turned by the expanding exhaust gases

 A cutaway of a typical turbocharger. The exhaust from the engine turns the turbine
on the left side at over 100,000 revolutions per minute. The turbine is connected by a
shaft to a compressor located on the right side of the turbocharger. The compressor
blades draw air from the air filter housing and force it into the Intake Manifold to give
power to the engine extra.

3.0.10.2 Boost Control
 Both supercharged and turbocharged systems are designed to provide a
pressure greater than atmospheric pressure in the Intake Manifold. This
increased pressure forces additional amounts of air into the combustion
chamber what would normally be forced in by atmospheric pressure.

3.0.10.2 Intercooler

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The higher the level of boost (pressure), the greater is the horsepower potential. However,

other factors must be considered when increasing boost pressure:

 As boost pressure increases, the temperature of the air also increases

 As the temperature of the air increases, combustion temperatures also increase,
which increases the possibility of detonation.

 Power can be increased by cooling the compressed air after it leaves the
turbocharger. The power can be increased about 1% per 10°F by which the air
is cooled. A typical cooling device is called an intercooler and is similar to a
radiator, wherein outside air can pass through cooling the pressurized heated
air.

 As boost pressure increases, combustion temperature and pressure increase,
which, if not limited, can cause severe engine damage.

An intercooler on a vehicle equipped with an aftermarket turbocharger is shown with the

bumper and grill removed.

3.0.10.3 Waste Gate

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 A turbocharger uses exhaust gases to increase boost, which causes the engine to
make more exhaust gases, which in turn increases the boost from the turbocharger.
To prevent over boosting and severe engine damage, most turbocharger systems use
a waste gate. A waste gate is a valve similar to a door that can be opened and closed.

 The waste gate is a bypass valve at the exhaust inlet to the turbine. It allows all of

the exhaust into the turbine, or it can route part of the exhaust past the turbine to the
exhaust system. If the valve is closed, all of the exhaust travels to the turbocharger.

 The waste gate is the pressure control valve of a turbocharger system. The waste

gate is usually controlled by the onboard computer through a boost control solenoid.

 The boost pressure on most turbocharged engines is controlled by the engine

computer by pulsing the boost control solenoid on and off basing on signals received
by the computer from the Manifold Absolute Pressure (MAP) sensor.

3.0.10.4 Relief Valves

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A waste gate controls the exhaust side of the turbocharger. A relief valve controls the
intake side. A relief valve vents pressurized air from the connecting pipe between the outlet
of the turbocharger and the throttle whenever the throttle is closed during boost, such as

during shafts.

3.10.0.5 There are two basic types of relief valves including:

 Compressor bypass valve or CBV. This type of relief valve routes the pressurized
air to the inlet side of the turbocharger for reuse and is quiet during operation.

 Blow-off valve or BOV. This is also called a dump valve or vent valve and features
an adjustable spring design that keeps the valve closed until a sudden release of the
throttle.

 A V-type engine has two exhaust manifolds, so two small turbochargers can be used
to help force greater quantities of air into an engine

 A blow-off

valve vents pressure to the atmosphere when the throttle is closed to help keep the
turbine blade from slowing when the pressurized air backs up after striking the closed
throttle plate

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3.0.11 A dual turbocharger system installed on a small block Chevrolet V-8 engine

Turbocharger failure

 When turbochargers fail to function correctly, a drop in power is noticed.
To restore proper operation, the turbocharger must be rebuilt, repaired or
replaced

Because there are no seals to keep oil in, excessive oil consumption is usually caused by:

 A plugged Positive Crankcase Ventilation (PCV) system resulting in
excessive crankcase pressures forcing oil into the air inlet. This failure is
not related to the turbocharger, but the turbocharger is often blamed.

 A clogged air filter, which causes a low-pressure area in the inlet, which can
draw oil past the turbo shaft rings and into the Intake Manifold.

 A clogged oil return (drain) line from the turbocharger to the oil pan
(sump), which can cause the engine oil pressure to force oil past the
turbocharger's shaft rings and into the intake and exhaust manifolds

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CHAPTER NO. 4

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VEHICLE EMISSION SOURCES

1. Types of Vehicle Emission Source
1. Exhaust Emissions

 The combustion process results in emissions of volatile Organic Compounds (VOC),
oxides of nitrogen (NOX), particulate matter (PM), and carbon monoxide (CO),
which are released from the tailpipe while a vehicle is operating. Exhaust emissions
occur during two modes:
a) Cold Start - Starting and driving a vehicle for the first few minutes results in
higher emissions because the emissions control equipment has not yet reached its
optimal operating temperature.
b) Running Exhaust Emissions - Pollutants are emitted from the vehicle’s tailpipe
during driving and idling after the vehicle is warmed up.

2. Evaporative Emissions
 Volatile Organic Compounds (VOCs) also escape into the air through fuel
evaporation. Evaporative emissions occur in several ways:
a) Running Losses - The hot engine and exhaust system can vaporize gasoline while the
vehicle is running.
b) Hot soak (Cooling Down) - The engine remains hot for a period of time after the
vehicle is turned off and gasoline evaporation continues when the car is parked while
cooling down.
c) Diurnal Emissions (Emissions while Parked and Engine is Cool)- Even when the
vehicle is parked for long periods of time, gasoline evaporation occurs as the
temperature rises during the day.
d) Refueling - Gasoline vapors escape from the vehicle’s fuel tank while the tank is
being filled.

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3. EXHAUST EMISSION POLLUTANTS AND THEIR EFFECTS TO HUMAN
HEALTH

1. HYDROCARBONS
 Hydrocarbon emissions result when fuel molecules in the engine do not burn or burn
only partially.
 Hydrocarbons react in the presence of nitrogen oxides and sunlight to form ground-
level ozone, a major component of smog.

 Ozone irritates the eyes, damages the lungs and aggravates respiratory problems.

 It is our most widespread and intractable urban air pollution problem. A number of

exhaust hydrocarbons are also toxic, with the potential to cause cancer.

2. NITROGEN OXIDES (NOx)
 Under the high pressure and temperature conditions in an engine, nitrogen and oxygen
atoms in the air react to form various nitrogen oxides, collectively known as NOx.
 Nitrogen oxides, like hydrocarbons, are precursors to the formation of ozone. They
also contribute to the formation of acid rain.

3. CARBON MONOXIDE
 Carbon monoxide (CO) is a product of incomplete combustion and occurs when
carbon in the fuel is partially oxidized rather than fully oxidized to carbon dioxide
(CO2).
 Carbon monoxide reduces the flow of oxygen in the bloodstream and is particularly
dangerous to persons with heart disease.

4. CARBON DIOXIDE
 In recent years, the U.S. Environmental Protection Agency (EPA) has started to view
carbon dioxide, a product of “perfect” combustion, as a pollution concern.
 Carbon dioxide does not directly impair human health, but it is a “greenhouse gas”
that traps the earth’s heat and contributes to the potential for global warming.

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4.0.4 FUEL EVAPORATING CONTROL SYSTEM

 The need to control the emissions from automobiles gave rise to the computerization
of the automobile. Hydrocarbons, carbon monoxide and oxides of nitrogen are created
during the combustion process and are emitted into the atmosphere from the tail pipe.

 There are also hydrocarbons emitted as a result of vaporization of gasoline and from
the crankcase of the automobile.

 They were called feedback fuel control systems. An oxygen sensor was installed in
the exhaust system and it would measure the fuel content of the exhaust stream.

5. GAS BLOW BY
 Internal combustion inevitably involves a small but continual amount of blow-by,
which occurs when some of the gases from the combustion leak past the piston rings
(that is, blow by them) to end up inside the crankcase. The gases could be vented
through a simple hole or tube directly to the atmosphere, or they could "find
their own way out" past baffles or past the oil seals of shafts or the gaskets of
bolted joints. Escape of oil and gases must be prevented via a closed system that
routes the escaping gases to the engine's intake stream and allows fresh air to come in.

6. TYPES OF EMISSION CONTROL SYSTEMS
1. CATALYTIC CONVERTER

 A Catalytic Converter is a device used to convert toxic exhaust emission from an
internal combustion engine into non-toxic substances. Inside a catalytic converter, a
catalyst stimulates a chemical reaction in which noxious by products of combustion
undergo a chemical reaction. Three-way Catalytic Converter reduces carbon
monoxide (CO), unburned hydrocarbons (HC), and oxides of nitrogen (NO, NO2, &
N2O) to produce carbon dioxide(CO2), nitrogen(N2), and water(H2O).

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CATALYTIC CONVERTER

4.0.6.2 EXHAUST GAS RECIRCULATION

 In internal combustion engines, Exhaust Gas Recirculation (EGR) is a nitrogen oxide
(NOx) emissions reduction technique used in petrol/gasoline and diesel engines.

 EGR works by recirculating a portion of an engine's exhaust gas back to the engine
cylinders. In a gasoline engine, this inert exhaust displaces the amount of combustible
matter in the cylinder. In a diesel engine, the exhaust gas replaces some of the excess
oxygen in the pre-combustion mixture.

 Because NOx is formed primarily when a mixture of nitrogen and oxygen is subjected
to high temperature, the lower combustion chamber temperatures caused by EGR
reduces the amount of NOx which the combustion generates.

4.0.6.3 EGR IN SPARKS-IGNITED ENGINES

 The exhaust gas, added to the fuel, oxygen and combustion products, increases the
specific heat capacity of the cylinder contents, which lowers the adiabatic flame
temperature.

 In a typical automotive spark-ignited (SI) engine, 5 to 15 percent of the exhaust gas is
routed back to the intake as EGR.

 The impact of EGR on engine efficiency largely depends on the specific engine
design, and sometimes leads to a compromise between efficiency and NOx emissions.
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 A properly operating EGR can theoretically increase the efficiency of gasoline
engines via several mechanisms.
a) Reduced throttling losses. The addition of inert exhaust gas into the intake
system means that for a given power output, the throttle plate must be opened
further, resulting in increased inlet manifold pressure and reduced throttling
losses.
b) Reduced heat rejection. Lowered peak combustion temperatures not only reduce
NOx formation, but also reduce the loss of thermal energy to combustion chamber
surfaces, leaving more thermal energy available for conversion to mechanical
work during the expansion stroke.
c) Reduced chemical dissociation. The lower peak temperatures result in more of
the released energy remaining as sensible energy near TDC, rather than being
bound up (early in the expansion stroke) in the dissociation of combustion
products.
d) Reduced specific heat ratio. A lean intake charge has a higher specific heat ratio
than an EGR mixture. A reduction of specific heat ratio reduces the amount of
energy that can be extracted by the piston.

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7. In diesel engines
 By feeding the lower oxygen exhaust gas into the intake, diesel EGR systems lower
combustion temperature, reducing emissions of nitrous oxides.
 This makes combustion less efficient, compromising economy and power. Diesel
EGR also increases soot production, though this was mitigated in the US by the
simultaneous introduction of diesel particulate filters.
 EGR systems can also add abrasive contaminants and increase engine oil acidity,
which in turn can reduce engine longevity.

1. EXHAUST GAS RECIRCULATION

8. POSITIVE CRANKCASE VENTILATION
 A crankcase ventilation system is a way for gases to escape in a controlled manner
from the crankcase of an internal combustion engine. A common type of such system
is a Positive Crankcase Ventilation (PCV) system, the heart of which is a PCV
valve—a variable-restriction valve that can react to changing pressure values and
intermittently allow the passage of the gases to their intended destination (which
nowadays is the engine's intake stream).

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8. SECONDARY AIR INJECTION CONTROL
 Secondary air injection (commonly known as air injection, or colloquially smog
pump) is a vehicle emissions control strategy introduced in 1966, wherein fresh air is
injected into the exhaust stream to allow a complete combustion of exhaust gases. An
implementation of the system has been trademarked by the name Air Injection
Reactor (A.I.R.).

4.0.9 PUMPED AIR INJECTION
 Pumped air injection systems use a vane pump turned by the engine via a belt. The
pump's air intake is centrifugally filtered by a rotating screen to exclude dirt particles
large enough to damage the system. Air is delivered under pressure to the injection
point(s). A check valve prevents exhaust forcing its way back through the air injection
system, which would damage the pump and other components.

 Carbureted engines' exhaust raw fuel content tends to spike when the driver suddenly
releases the throttle. To prevent the startling and potentially damaging effects of the
explosive combustion of this raw fuel, a diverter valve is used. This valve senses the
sharp increase in intake manifold vacuum resulting from the sudden closure of the
throttle and diverts the air pump's outlet to atmosphere. Usually this diverted air is
routed to the engine air cleaner or to a separate silencer to muffle objectionable pump
noise.

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4.0.10 ASPIRATED AIR INJECTION
 Air injection can also be achieved by taking advantage of the negative pressure pulses

in the exhaust system at engine idle. A sensitive reed valve assembly called the
aspirator valve is placed in the air injection plumbing, which draws its air directly
from the clean side of the air filter. During engine idle, brief but periodic negative
pressure pulses in the exhaust system draw air through the aspirator valve and send
into the exhaust stream at the catalytic converter.

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CHAPTER 5

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AUTOMATIC TRANMISSION

1. AUTOMATIC TRANSMISSION
1. FUNCTION
Automatic transmission is a system in which gearbox can change gears automatically while
the vehicle is moving without requiring the driver to change
gears manually. Most car models sold in the United States, Japan, Singapore and recently in
Malaysia use automatic transmission.

EXAMPLES FOR AUTOMATICS CAR

2. Automatic Transmission Mode
 Automatic transmission is operated by only moving the gear knob to a certain
position. Some models with automatic transmission also use buttons to replace
the gear knob, thus saving space. The position of the automatic transmission mode
is arranged by format3-2 PRND-L, either from left to right or from top to bottom. The
engine can be turned on when in position P or N only.

3. Construction
a) Torque converter
b) The planetary gear set
c) valve body
d) Automatic transmission fluid (ATF)

4. Components of Automatic Transmission
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5.0.5 Automatic Transmission Gearbox

6. Torque Converter

1. FUNCTION

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 Takes over the clutch for manual transmission and produces some slippage to enable
the engine to operate without the engine to be stopped due to low spin, such as
when to withdraw or begin to move in first gear.

5.0.6.2 The Torque Converter

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