Seminar - Copy - Copy

TRIBHUVAN UNIVERSITY INSTITUTE OF ENGINEERING THAPATHALI CAMPUS

A report of Seminar Paper on Electronic Fuel Injection By Sujan Khadka (45690)

A REPORT SUBMITTED TO DEPARTMENT OF INDUSTRIAL ENGINEERING FOR THE PARTIAL FULFILLMENT FOR THE DEGREE OF BACHELOR IN INDUSTRIAL ENGINEERING

DEPARTMENT OF INDUSTRIAL ENGINEERING THAPATHALI, KATHMANDU, NEPAL

OCTOBER, 2016

Copyright The author has agreed that the library, department of Industrial Engineering, Thapathali Campus, and Institute of Engineering may make this report freely available for inspection. Moreover, the author has agreed that permission for extensive copyright of this project report for scholarly purpose may be granted by the professor who supervised the project work recorded herein or, in their absence, by the head of the department wherein the project report was done. It is understood that recognition will be given to the author of this report and to the department of industrial engineering, Thapathali Campus, Institute of Engineering in any use of material of this project report. Copying or publication or the other use of this report for financial gain without approval of the department of Industrial Engineering, Thapathali campus, Institute of Engineering and authors written permission is prohibited. Request for permission to copy or to make any other use of the material in this report in whole or in part should be addressed to: Head Department of Industrial Engineering Thapathali campus, Institute of Engineering Thapathali, Kathmandu, Nepal

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TRIBHUVAN UNIVERSITY INSTITUTE OF ENGINEERING THAPATHALI CAMPUS DEPARTMENT OF INDUSTRIAL ENGINEERING

It is hereby certified that this report, entitled “A report of Seminar paper on Electronic Fuel Injection System” is prepared by Sujan Khadka The facts and ideas presented in this report are an outcome of the student’s hard work and dedication to the project, undertaken as a partial fulfillment for requirements for degree of Bachelor in Industrial Engineering. The outcome of this project has been highly appreciated.

……………………… Er. Subodh Kumar Ghimire Supervisor ……………………… Mr. Prem Lama External Evaluator ………………………. Er. Ishwar Chandra Baniya Campus Chief ……………………….. Er. Sudan Neupane Head of Department 3

Acknowledgement First of all I would like to thank the Department of Industrial Engineering for providing the students with the opportunity to get some knowledge through seminar report preparation. I would like to express my sincere gratitude to Er. Sudan Neupane (HOD, Department of Industrial Engineering, Thapathali Campus) for his guidance and moral support for the preparation of this seminar report. I would also like to thank Er. Bishwo Ram Parajuli (Deputy HOD, Department of Industrial Engineering) for his valuable suggestion. Likewise, I am grateful to Er. Akash Prajapati (Service Advisor, LI Service Centre Pvt. Ltd) for all the paths he have shown me during this paper writing. At last I am very thankful to the many people who saw me through this paper; to all those who provided support, talked things over, read, wrote, offered comments, allowed me to quote their remarks and assisted in the editing, proofreading and design. Finally I would like to assure that the report has been prepared to best of my knowledge acquired till present date.

Sujan Khadka

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Abstract Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines by an injector. All diesel engines use fuel injection by design. Petrol engines use gasoline direct injection where the fuel is directly delivered to the combustion chamber, or indirect injection where the fuel is mixed with air before the intake stroke. On petrol engines fuel injection replaced carburetors from the 1980s upward. The primary difference between the carburetor and fuel injection is that fuel injection atomizes fuel through small nozzle under high pressure, while carburetor relies on suction created by intake air accelerated through a venturi tube to draw the fuel into the upstream which is a significant difference in operation of the two process. Carburetors provide fuel control by purely fluid dynamic means, utilizing jets and similar devices to control fuel flow while sliding or rotating valves control airflow. The relationship between the airflow and the fuel flow is essentially adjusted mechanically, but various methods have been used over the years in an attempt to provide a form of compensation for different operating conditions. Small carburetors are usually very basic and do not incorporate the advanced compensation devices found on larger carburetors. However, even if small carburetors could be equipped with larger standard compensating systems, the end result would not be as effective as EFI. In EFI systems, the carburetor is eliminated. Airflow regulation continues to be achieved using a butterfly or a rotating valve, but an electronically controlled fuel injector delivers the required quantity of fuel. The amount of fuel and the amount of air delivered can be regulated independently. The system provides the required fuel/air delivery based on the information provided by various sensors. These include the inlet manifold air and cylinder head temperature sensors, the crank position sensor, the barometric and manifold pressure sensors, and the throttle position sensor. An electronic control unit (ECU) performs the computations that are required to optimize both fuel delivery and ignition timing. EFI systems enable the fuel/air ratio to be continuously adjusted according to the operating conditions (altitude, ambient temperature etc) and the engine requirements (throttle opening, power/overrun conditions, cold/hot start etc).

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Keywords: Fuel injection, Carburetor, EFI system, ECU, fuel efficiency

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TABLE OF CONTENTS Copyright ................................................................................................................................... 2 Acknowledgement ..................................................................................................................... 4 Abstract ...................................................................................................................................... 5 TABLE OF CONTENTS ........................................................................................................... 7 List of Figures ............................................................................................................................ 8 List of Abbreviations ................................................................................................................. 9 CHAPTER ONE INTRODUCTION ....................................................................................... 10 1.1 Objectives .......................................................................................................................... 10 1.1.1 General objectives:.......................................................................................................... 10 1.1.2 Specific objectives .......................................................................................................... 10 1.2 Components of EFI ............................................................................................................ 10 1.3 Basic operation................................................................................................................... 11 1.3.1 Electronic Control Unit ................................................................................................... 12 1.3.2 Working of ECU Control of fuel injection ..................................................................... 12 CHAPTER TWO LITERATURE REVIEW .......................................................................... 14 2.1 Development of Electronic Fuel Injection ......................................................................... 14 2.1 Types of EFI ...................................................................................................................... 14 2.1.1 Throttle Body Injection Systems .................................................................................... 15 2.1.2 Multipoint Fuel Injection System (MPFI) ...................................................................... 16 2.1.3 Gasoline Direct Fuel Injection Systems (DFI)................................................................ 17 2.2 Differences between MPFI and DFI Systems .................................................................... 19 2.3 Comparison between Fuel injection and Carburetors ........................................................ 20 CHAPTER THREE ADVANTAGES AND DISADVANTAGES OF EFI............................ 23 3.1 Advantages of EFI ............................................................................................................. 23 3.2 Disadvantages of EFI ......................................................................................................... 24 CHAPTER FOUR CONCLUSION AND RECOMMENDATIONS ..................................... 25 4.1 Conclusions ........................................................................................................................ 25 4.2 Recommendations .............................................................................................................. 25 REFERENCES ........................................................................................................................ 26

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List of Figures Figure 1.1: EFI ......................................................................................................................... 11 Figure 2.1: Throttle body injection .......................................................................................... 15 Figure 2.2: Multipoint Fuel Injection System .......................................................................... 17 Figure 2.3: Gasoline Direct Injection System .......................................................................... 19

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List of Abbreviations DFI

Direct Fuel Ignition

ECM

Engine Control Module

ECU

Engine Control Unit

EFI

Electronic Fuel Injection

GDI

Gasoline Direct Injection

LPG

Liquidified Petroleum Gas

MPFI

Multi-Point Fuel Injection

PCM

Powertrain Control Module

PSI

Pounds per Square Inches

TBI

Throttle Body Injection

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CHAPTER ONE INTRODUCTION Electronic fuel injection (EFI) is the substitute for the conventional metering system which mixes the air and fuel in correct ratio before feeding it down to the main cylinder to power the vehicle. A carburetor was widely used for the very purpose before. But the downside of using the carburetor is that it has fixed settings and certain limitations .To overcome such limitations new system has been introduced. However for this new system to work it needs data from several sensors. This system includes engine speed sensor, temperature sensor, voltage sensor, throttle position sensor, oxygen sensor and an air flow sensor. The data collected from various sensors are sent to the electronic control unit. The ECU makes use of data collected from various sensors to determine the spark advance, the length of other spark and other parameters. Then the exact air-fuel mixture for that particular instant is fed into the cylinder which in turn delivers optimum power and clean exhaust. All this process is done continuously and happens many times in every second. 1.1 Objectives The objectives of this seminar paper can be underlined in following two headings: 1.1.1 General objectives: 

To know about the usefulness of EFI system

1.1.2 Specific objectives: 

To know about different types of EFI system



To compare the performance of EFI system with that of carburetor



To know about the advantages and disadvantages of EFI

1.2 Components of EFI a) Injectors: When signaled by the engine control unit the fuel injector opens and sprays the pressurized fuel into the engine. The duration that the injector is open (pulse width) is open is proportional to the amount of fuel delivered. Depending upon the system design, the timing of when injector opens is either relative each individual cylinder (for a sequential fuel injection system), or injectors for multiple cylinders may be signaled to open at the same time (in a batch fire system)

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b) Engine Control Unit: The engine control unit is central to an EFI system. The ECU interprets data from input sensors to, among other tasks, calculate the appropriate amount of fuel to input. c) Fuel pump: It feeds fuel through a hose/line to the engine d) Fuel pressure regulator: It is constant fuel pressure maintaining device for proper fuel atomization e) Wiring Harness: It is wiring assembly which transmits electrical power or signals f) Various sensors : They are used to convey information to ECU. Some of the sensors are Hall effect sensor-crank/cam position sensor, MAF sensor-airflow sensor, Oxygen sensor, EGO sensor(exhaust gas oxygen sensor)

Figure 1.1: EFI (Thorat) 1.3 Basic operation 

The fuel enters through the air induction system where it is measured by the air induction system where it is measured by air flow meter. As the air flows into the cylinder, fuel is mixed into the air fuel injector.

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

Fuel injectors are arranged in the intake manifold behind each inake valve. The injectors are electrical solenoids which are operated by ECU.



The ECU pulses the injector by switching the injector ground circuit on and off.



When the injector is turned on, it opens, spraying atomized fuel at the back side of the intake valve.



The precise amount of fuel delivered to the engine is a function of ECU unit.



The ECU determines the basic injection quantity based upon measured intake air volume and engine rpm.

(Air induction system consists of the air cleaner, air flow meter, throttle valve, air intake chamber intake manifold number, and intake; when the throttle valve is open air flows through the air cleaner, through the air flow meter, past the throttle valve, and through a well tuned intake manifold runner to the intake.) 1.3.1 Electronic Control Unit Electronic Control Unit (ECU) is a embedded system that controls one or more of the electrical systems or subsystems in a motor vehicle. An engine control unit (ECU), also known as power-train control module (PCM), or engine control module (ECM) is a type of electronic control unit that determines the amount of fuel, ignition timing and other parameters an internal combustion engine needs to keep running. It does this by reading values from multidimensional maps which contain values calculated by sensor devices monitoring the engine. 1.3.2 Working of ECU Control of fuel injection ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up yet, more fuel will be injected. Control of ignition timing: A spark ignition engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy.

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Control of idle speed: Most engine systems have idle speed control built into the ECU. The engine RPM is monitored by the crankshaft position sensor which plays a primary role in the engine timing functions for fuel injection, spark events, and valve timing. Idle speed is controlled by a programmable throttle stop or an idle air bypass control stepper motor.

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CHAPTER TWO LITERATURE REVIEW 2.1 Development of Electronic Fuel Injection While the fuel in gasoline engines was metered with carburetors almost from the beginning, fuel injection technology has been widely used for other types of fuel since the 1980s, beginning with Frederick William Lanchester’s first days at the Forward Gas Engine Company, in Birmingham England. Beginning in 1889, he conducted some of the first experiments with the technology, and his work was soon expanded upon by E.J Pennington, who had included an extremely crude version of fuel injection in the patent for his motorcycle design in 1896. Not long after, Herbert Akroyd Stuart developed the first version of fuel injection to resemble modern systems. It used a ‘jerk pump’ to measure out fuel oil at very high pressure, feeding it to an injector. The system was later adopted by Rudolf Bosch to replace Rudolf Diesel’s original ‘air-blast’ system on diesel engines. By the 1920s fuel injection was widely used on diesel engines, and was being adapted for use in gasoline-powered aircraft because it was less susceptible to the unpredictable g-force changes on an airplane engine. Fuel injection would eventually be used during World War II on such planes. Fuel injection didn’t really come into play on commercial gasoline engine systems until after the war had ended. Today fuel injection, and specifically Electronic Fuel Injection, the technology for mixing air and fuel in an internal combustion engine has become the automotive design standard, almost completely replacing carburetors. (The Development of Fuel Injected EnginesA Brief History) 2.1 Types of EFI There are three basic EFI systems: throttle body injection, also called single-point injection; multipoint fuel injection; and gasoline direct injection, or simply direct injection. The specific characteristics of each of these designs are different, but they all operate on similar principles: Fuel is supplied to the injectors at the specified pressure, the PCM sends an electric signal to each injector to cause it to open for a certain amount of time (pulse width), and fuel is injected into the intake manifold or combustion chamber.

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2.1.1 Throttle Body Injection Systems Throttle body injection (TBI), also known as single-point injection or central-point injection, is a system with one or two fuel injectors located centrally on the intake manifold, right above the throttle plates. Fuel is sprayed into the top center of the throttle body and then atomized with the incoming filtered air. This air–fuel mixture is then delivered to each of the engine’s cylinders evenly. TBI is a simpler system, requiring only one or two injectors, meaning the PCM can be of a simpler, less powerful design. And since the fuel is sprayed above the throttle plates, it is at atmospheric pressure, so the pressure drop across the injector is always the same. Thus, fuel pressure does not need to change with throttle opening or engine load. (Pimenta, 1998) In TBI systems, the central injector is normally triggered on every ignition pulse. However, if there are two injectors, alternate triggering may be used. At idling speeds, the frequency may be less to provide finer control. TBI is the predecessor to modernday multipoint (or multiport) fuel injection.

Figure 2.1: Throttle body injection The advantages are: 1. Only one fuel injector; 2. The system pressure is not dependent on the intake air pressure; 3. Reduced fuel consumption - precise adaptation of engine changing conditions; 4. Improved performance through greater latitude of the intake tract;

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5. The large distance of heat-stressed parts leads to fewer steam bubbles and a cheaper delivery pump. Sensor used: 1. Inductive pickup - position of the crankshaft and speed of the engine; 2. Lambda probe; 3. Temperature sensors for cooling water system and air intake system; 4. Throttle potentiometer 2.1.2 Multipoint Fuel Injection System (MPFI) For any injection duration, if fuel is held at constant pressure, then as manifold pressure varies, so does the amount of fuel delivered. That means fuel pressure must be held constant above manifold pressure. This pressure is held by sealing the spring housing of the pressure regulator and letting it sense manifold pressure via a connecting hose. Then, when manifold pressure changes, so does the fuel pressure. When manifold pressure is low (high vacuum), as it is at idling, fuel pressure is low. As manifold pressure rises (low vacuum), toward open throttle, fuel pressure rises. Since the injectors are all subjected to the same pressure, they all inject an equal amount of fuel. The quantity of fuel delivered is thus controlled accurately by the pulse width of the injector. The manifold pressure sensing is not required in TBI systems, as the injection occurs above the throttle plate, at atmospheric pressure; thus fuel pressure is determined by the force of the regulator spring acting on the diaphragm. The injectors are sealed into the manifold by O-rings that prevent air entering at that point. The O-rings, together with plastic caps on the injector nozzles, also act as a barrier to heat being transferred to the injector body. For a short time after an engine is switched off, the engine temperature keeps rising, which can produce vapor in the fuel lines. A check valve in the pump maintains the fuel pressure in the system after engine shut down, preventing the fuel from boiling (vaporizing) as it absorbs heat from the engine (heat soak) This pressure will diminish in about 20 to 30 minutes, but it ensures effective hot-starting capability of the engine. When the engine is running, the circulation of fuel ensures that cool fuel is delivered at all times and that vapor formation in the lines is prevented. The pump control

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circuit normally allows the pump to operate for only a few seconds when the ignition is switched on; this is for priming the system. The pump control circuit allows the pump to operate during cranking and when the engine is running above a specified minimum revolutions per minute (rpm).

Figure 2.2: Multipoint Fuel Injection System Sensors used: 1. Inductive pickup - position of the crankshaft and speed of the engine; 2. Lambda probe; 3. Temperature sensors for cooling water systems 4. Throttle potentiometer 5. Air-flow meter 6. Air temperature sensor (Berisha) 2.1.3 Gasoline Direct Fuel Injection Systems (DFI) With the pressures to reduce emissions and increase fuel economy, as well as gain an advantage over the competition and offset the escalating price of crude oil, manufacturers have looked to new technologies in fuel injection. Just as TBI replaced carburetion, gasoline direct injection (GDI) is the natural successor to indirect fuel

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injection. While indirect fuel injection atomizes fuel at or near the intake valve, GDI systems take their design cues from diesel technology by spraying the fuel directly into the cylinder. Because of this direct injection, engines can run on extremely lean fuel mixtures—much leaner than stoichiometric. The fuel injector of each cylinder is located in the cylinder head. Fuel is directly sprayed into the combustion chamber as an atomized mist at the precise time it is needed, depending on the operating conditions of the engine. The reason this type of engine can run so lean is because the injector can place the fuel in a localized spot surrounding the spark plug. This is called a stratified charge because the fuel is mixed with air in just a small area, not thoroughly dispersed among the entire amount of air in the combustion chamber. So far GDI engines still use spark plugs. Use of spark plugs provides the computer with more choices as to when the fuel gets injected. For example, during heavy load conditions, a slightly rich mixture is injected during the intake stroke. This gives more time for the larger amount of fuel to mix more fully with the air, creating maximum power and reduced spark knock. During moderate engine loads, just enough fuel is injected during the intake stroke to create a stoichiometric air–fuel ratio, to again fully mix with the air. This results in good power and a very clean burn. Under light load or cruise conditions, if the fuel pump is designed to deliver the high pressures needed to overcome the compression pressures, the fuel is injected as described earlier, during the latter stages of the compression stroke, and is placed near the spark plug. This small amount of air and fuel is surrounded by a larger amount of air, which helps insulate the cylinder walls from the heat of combustion. This design reduces heat loss in the combustion chamber and increases fuel economy. GDI fuel systems can be of either a low-pressure variety (only inject during the intake stroke or early in the compression stroke) or a high-pressure variety (can inject during the intake stroke, the compression stroke, and potentially the power stroke).

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Figure 2.3: Gasoline Direct Injection System 2.2 Differences between MPFI and DFI Systems Sharing some of the same features, MPFI and DFI systems exhibit some key differences from each other. These differences mostly occur in how they deliver fuel to the combustion chamber. The following sections give more information on the differences between MPFI and DFI systems. 1. Point of Fuel Injection Delivery of the fuel to the combustion chamber represents the main difference between the two fuel system types. The MPFI system delivers the fuel to a point close to the intake valve. The fuel and air mix before entering the combustion chamber during the intake stroke. A DFI system delivers the fuel to within the combustion chamber, combining the fuel and air as the air is drawn into the chamber on the intake stroke. The direct injection method improves the overall fuel efficiency of the engine over the multi-point fuel injection system. A direct injection system also allows for better fuel control. This in turn lowers the emission levels put out by the vehicle. 2. Sequence of Injection

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As mentioned earlier, an MPFI system can operate either using a sequential, batched, or simultaneous injection delivery system. Modern electronic fuel injection systems use a sequential MPFI. Direct injection systems have gained ground on their multipoint predecessors, being placed in newer gasoline engines. Due to the high fuel pressures involved, DFI systems deliver their fuel quickly, as a common fuel rail feeds each cylinder at the same time. 3. Fuel Pressure Fuel pressure in the DFI system varies greatly from its MPFI system predecessor. The typical fuel pressure produced in an MPFI system runs around 50 to 60 PSI. A DFI system, on the other hand, can produce fuel pressures from around 1000 to as high as 26,000 PSI, which is a big difference and, if care is not taken while servicing a DFI engine, a dangerous amount of pressure. (Rocio, 2002) 4. Compression Ratio When it comes to compression, the higher the compression produced, the more horsepower an engine can put forward as power to run the vehicle. When dealing with the difference in horsepower produced by a DFI engine compared to an MPFI, there is no mistaking the better performance of the DFI system. In comparison, a DFI system produces roughly four to five per cent more horsepower than an MPFI system. 5. Cost When it comes down to cost, the MPFI system beats a DFI system hands down. A product of the higher heat and stresses placed upon a DFI system as the delivery mechanism is within the combustion chamber, which exposes the DFI system more to the heat and stresses caused when the fuel and air mixture combusts in the chamber.

2.3 Comparison between Fuel injection and Carburetors There have long been arguments over the pros and cons of carburetors when weighed against engines with fuel injection. It’s true that both have their advantages and disadvantages. However, a great deal depends on what you actually like in an engine. Both have plenty to offer and can give great service. 1. Cost

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An engine with a carburetor costs around five times less than one with fuel injection which makes for a very large savings. However, the maintenance costs of a carburetor engine are generally higher than for one with fuel injection so it can all even out in the long

run.

Even fuel injection prices can vary greatly. Direct fuel injection, in particular, tends to be much higher in cost than common port fuel injection. 2. Emissions Emissions are major factors in modern motoring and is likely to be even more critical in the future. This is where fuel injection has many advantages. Carburetor engines were fine when little attention was ever paid to the amount of CO2 being emitted but these days, the restrictions on vehicle emissions means that more and more manufacturers will be leaning toward fuel injection for their vehicles. 3. Fuel Economy 4. Again, the nod for fuel economy goes to fuel injection. The way a carburetor is set up means that to obtain truly excellent fuel economy, you’d constantly need to be tinkering with the settings to allow for variations in weather and atmosphere and this isn't particularly practical. As gas prices increase, carburetor engines are becoming less and less sought after. 5. Performance If power and performance are the main criteria in your choice of engine, you’ll be firmly on the side of carburetors. This is because a carburetor engine has no limit on the amount of gas that can be pumped from the tank. This means that cam modifications will let more fuel come through the carburetor and into the cylinders. This results in a denser mixture in the chamber and higher levels of power. The only way to try and rival this with fuel injection is by turbo-charging or supercharging to attain the same kind of flexibility. For normal daily driving, however, extra power doesn’t really matter. Extra power is always going to lead to greater gas consumption which, in turn, will lead to greater costs. 6. Simplicity A carburetor is very complex and needs to be adjusted properly in order to work efficiently. By contrast, a fuel injection setup is extremely simple. A carburetor relies on a float and needs to regulate the amount of fuel passing through to the engine. 21

With a carburetor engine, one cylinder will receive more fuel than another cylinder. In a fuel injection engine, each cylinder receives the same amount of fuel. In this particular area, there’s little that can be done to improve the design of the carburetor. With fuel injection systems, the fuel runs through a line under pressure to the fuel injectors. The car’s computer instructs each injector on when it should open and at this point, the fuel enters the cylinders. As it passes through the cylinder, fuel becomes atomized so it burns more effectively.

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CHAPTER THREE ADVANTAGES AND DISADVANTAGES OF EFI 3.1 Advantages of EFI EFI is at the forefront of engineering development to optimize the overall efficiency of the engine. Following are its advantages : 1. Intelligence The engine control unit (ECU) is the brain of the EFI engine and the reason for many advantages of EFI. The ECU interprets a variety of information from sensors throughout the engine so that it can continually run at an optimal level.

2. Reduced fuel consumption & emissions By monitoring the engine sensors, the ECU determines the precise amount of fuel that needs to be delivered by the injector. It also delivers the exact air/fuel ratio to the engine by activating the injectors for the precise amount of time.

3. Less servicing Not only are there no carburetor maintenance or replacement costs, there is also less servicing needed in general. The fuel system, for example, is entirely sealed so the gasoline does not encounter oxygen, which causes it to go bad. This prevents the needs for bringing the engine in for servicing in the spring as a result of contaminated gas.

4. Altitude adaptability Changes in altitude can affect any engine’s performance and in higher altitudes there is less oxygen. In a carbureted engine, operators would be required to change the carburetors jetting, but with EFI, it automatically compensates for the change in altitude by sensing the air temperature and density. It would then modify the fuel flowing through the injectors to provide the correct mixture for that current altitude.

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5. Eliminating carburetor float problems An EFI system is all electronic. Because of this it has an injector, which means it doesn’t require a fuel float that you would find in a carburetor. The carburetor floats can bounce around causing a lot of problems, especially with the movement of vehicles.

3.2 Disadvantages of EFI 1. Maintenance Hazards Fuel injection introduces potential hazards in engine maintenance due to the high fuel pressures used. Residual pressure can remain in the fuel lines long after an injectionequipped engine has been shut down. This residual pressure must be relieved, and if it is done so by external bleed-off, the fuel must be safely contained. If a high-pressure diesel fuel injector is removed from its seat and operated in open air, there is a risk to the operator of injury by hypodermic jet-injection, even with only 100 psi (6.9 bar) pressure. The first known such injury occurred in 1937 during a diesel engine maintenance operation. (Kunjam, 2000) 2. High Cost An engine with a carburetor costs around five times less than one with fuel injection which makes for a very large savings. However, the maintenance costs of a carburetor engine are generally higher than for one with fuel injection so it can all even out in the long run. Nevertheless high cost price of EFI can be considered as disadvantage 3) Skilled manpower EFI can be considered a new concept and hence there are less manpower in the world to maintain, repair and develop this system. Thus the required manpower are scarce.

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CHAPTER FOUR CONCLUSION AND RECOMMENDATIONS 4.1 Conclusions The main conclusions from the information presented in this paper are as follow: 1. Electronic control of fuel injection is feasible and may easily provide the control flexibility necessary for optimum overall engine efficiency. 2. An electronically actuated injection valve with sufficient flow rate and actuation speed can be fabricated and applied in either port or direct fuel injection. 3. The development in electronic fuel injection injection system has made it possible to overcome the level of pollution and improve the performance of engine in term of parameters like fuel consumption. 4. The optimization of injection timing greatly reduces the specific fuel consumption and exhaust emission due to better control over the air fuel ratio. EFI is mainly renowned for reducing exhaust emission. However, in addition to reduced exhaust emission, EFI has also introduced other benefits such as reduced brake specific fuel consumption, increased full-load output and improved drive ability. 4.2 Recommendations The recommendations proposable from this study are as follow: 1. EFI should be applied as it has several disadvantages in spite of the disadvantage of its high cost. 2. Carburetors have long served the performance aftermarket and the switch from carburetor to ‘self tuning- EFI’ technology in present world seems so apt and a necessity

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REFERENCES Berisha, D. S. Sensors used in EFI . Phoenix. Kunjam, R. K. (2000). A Study on Advance Electronic Fuel Injection System. Raigarh. Pimenta, R. (1998). Fuel injection systems (gasoline). Rocio, Q.-C. M. (2002). Application of EFI. The Development of Fuel Injected Engines- A Brief History. (n.d.). Retrieved September 2016, from oldcarandtruckpictures.com Thorat, S. (n.d.). Mechanical Engineering Seminars. Retrieved September 2016, from www.mechengg.net

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