This presentation is about complete description of EFI system. How it works.

2. Group Members
1- Khdija Hassan BMEF14M001
2- M.Saleem BMEF14M003
3- Mohsin Ikram BMEF14M007
4- Ghulam Mustafa BMEF14M008
5- Moeed Ahsan BMEF14M009
6- Hafiz Zia-ur-Rehman BMEF14M030
7- M.Talha Hanif BMEF14M033

3. Contents
Introduction
Air Induction System
Input (Sensors)
ECU/M( Electronic Control Unit/Module)
Output (Actuators)/Fuel Delivery System
Advantages/ Disadvantage

4. 
INTRODUCTION
The Electronic Fuel Injection system fitted to most
modern vehicles combines sophisticated computer
controls with a high pressure fuel delivery system to
provide optimum power and fuel efficiency.
 It uses the Electronic Sensors for Precise metering of
fuel.
 The system is controlled by an electronic control unit
(ECU).
 Replacement for Carburetor.
 Not engine vacuum, is used to feed fuel into engine.
 Pressure is used from an electric fuel pump.

6. Types of EFI System
 Single Point Injection System
 Multi Point Injection System
 Direct Injection System
 Indirect Injection System

7. Single Point Injection
 It is also called TBI.
 Injector located inside
throttle body.
 Injector sprays
fuel from above
throttle valve.
 ECU controls
injector opening

8. Multi Point Injection System
 Injector located in each
branch of inlet manifold,
below throttle valve.
 Injectors spray fuel
directly into each port.
 ECU controls
opening of injectors

9. Direct Injection
 Injector is fixed to the top
of combustion chamber.
 Fuel is injected above
Piston head.
 Smaller combustion space,
better thermal efficiency.

10. Indirect Injection
 Indirect Injection System
has a small swirl chamber
above the cylinder.
 Fuel is injected in swirl
chamber.
 Higher compression ratio
needed to aid starting.

11. Conventional/Carburetor Engine
1-Difference of Pressure 2- Vanturi. 3-Float
chamber.

12. Conventional/Carburetor Engine
 The air induction system consists of the air
cleaner, air flow meter, throttle valve, air intake
chamber, intake manifold runner, and intake
valve.
 When the throttle valve is opened, air flows
through the air cleaner, through the air flow
meter (on L type systems), past the throttle valve,
and through a well tuned intake manifold runner
to the intake valve.
Air Induction System

13. Air Induction System

14. Air Cleaner : The Air Cleaner is a
functional part that purifies
vehicle intake air used for engine
combustion.
Air Cleaner Element:The Air Cleaner
Element (or Air Filter) is placed
inside the Air Cleaner to eliminate
dust, carbon and other pollution
contained within the intake air
from reaching the engine.
Air Induction System

15.  Airflow meters are basically mass flow meters, as
they determine the air velocity and air pressure by
measuring the mass flow of a medium, which is air in
this case.
Air Induction System

16.  The throttle body is the part of the air intake system that
controls the amount of air flowing into an engine's
combustion chamber. It consists of a bored housing that
contains a throttle plate that rotates on a shaft. When the
accelerator is depressed, the throttle plate opens and
allows air into the engine. When the accelerator is released,
the throttle plate closes and effectively chokes-off air flow
into the combustion chamber. This process effectively
controls the rate of combustion and ultimately the speed of
the vehicle.
The throttle body is usually located between the air filter
box and the intake manifold, and it is usually located near
the mass airflow sensor.
Air Induction System

17. Sensors (Inputs)

18. Intake Air Temperature Sensor
It measures the temperature of the air entering the engine.

19. Throttle Position Sensor
A throttle position sensor (TPS) is a sensor used to
monitor the throttle position of a vehicle.

20. Camshaft Position Sensor
This sensor is responsible for telling the ECU the current
position of the camshaft.

21. Manifold Absolute Pressure Sensor
It senses the difference between atmospheric pressure and
the engine vacuum pressure.

22. Vehicle Speed Sensor
It is used for reading the speed of a vehicle's wheel
rotation/speed.

23. Coolant Temp Sensor
 It is used to measure the “temp” of the engine coolant of an IC Engine.
 How does it work?
I. ECU sends out regulated voltage to the coolant sensor.
II. Voltage drops across it changes according to the temp because its RESISTANCE
changes.
III. Voltage drop is measured by the ECU and carry out adjustments according to this.
Locations: on the bottom of the radiator.

24. Mass Air Flow Sensor
 It is to measure the amount of air entering the engine or the air flow.
 How does “Hot Wire Sensor” work?
I. Const. voltage is applied to the wire, heated by the current produced by the applied
voltage, and it is placed in the position of the air stream.
II. As the air flows, its temperature drops, as a result of this resistance also drops.
III. It allows the more current to draw through it to maintain the initial temperature.
 Location: The MAF Sensor is located either on the air cleaner box or along the pipe
going from the air cleaner to the throttle body.

25. Oxygen Sensor
 It is used to measures the proportion of oxygen (O2) in the exhaust.
 How does “O2 Sensor” work?
I. It actually compares the amount of oxygen that is present in exhaust gas and the
ambient air.
 Location: These are located within the exhaust stream, there is at least one oxygen
sensor located before the catalytic converter and typically one in each exhaust
manifold.

26. Knock Sensor
 It is used to detect the “VIBRATIONS” produce by the Engine Knocking.
 How does it work?
I. It is a piezoelectric sensor. That changes the vibrations sense by it into the voltage
signal.
 Location: This sensor is normally bolted onto the main-body of the engine.

27. Crankshaft Sensor
 It is responsible for telling the exact location of the crankshaft as well as the RPM of
the engine.
 How does it work?
I. It is positioned so that the teeth on the reluctor wheel are in contact with the tip of the
sensor.
II. As crankshaft rotates sensor produces a voltage signal corresponding to the teeth.
 Locations: It is located at the bottom of the engine somewhere close to the crankshaft.

28. Electronic Control Unit(ECU)

29.  It’s a type of electronic control unit that controls a
series of actuators on an IC engine to ensure optimal
engine performance.

30. Memory maps:

31. Functions:
 Control of air/fuel ratio
 Control of idle speed
 Variable valve timing(VVT)
 Ignition timing
 Waste gate control
 Speed limit

34. Fuel Delivery System and Actuators(OutPut).
 Fuel Tank/Filter
 Fuel pump
 Fuel Rail/Relay & Return Line
 Fuel pressure regulator
 Fuel injectors
 Valves
 Spark Plug

35.  Mounted inside or near the fuel tank
 May range anywhere from 8 to 80 lbs.
 Relay sends a signal to the ignition switch
 All other actuators and components in the injection
system depend on powering the Relay.
Fuel Pump and Relay

36. Fuel pressure regulator
 means of regulating fuel pressure according to
engine vacuum
 mounted on the fuel rail that supplies the injectors.
 has a simple spring-controlled vacuum diaphragm
with a vacuum connection to the intake manifold
 The excess fuel pressure is shunted through a bypass
port back to the fuel tank

37. Fuel injector
 Output actuators such as fuel injectors are devices
that are activated by the ECU with reference to the
engine’s load and condition it is in.
 A spring-loaded solenoid pintle valve
 Pulse width
 common problem

38. Valves
 Allow the intake of different fluids involved in the
injection of air, the mixture, and the fuel.
 Canister valve: A key component for
the emission control system. Thanks to the
movement of this valve, vapours contained in the
fuel tank are transported into the engine,
 – IAC (Idle Air Control) Valve: adjust the
engine idling revolutions, managing and
regulating the influx of air towards the combustion
chamber

39. Spark plug
 This spark plug is used to ignite the charge inside
the engine by applying high voltage across the
terminal of electrode

40. Advantages Over Conventional System
 Improved atomization. Fuel is forced into the intake
manifold under pressure.
 Better fuel distribution.
 Lower emissions. Lean efficient air-fuel mixture
reduces exhaust pollution.
 Better cold weather drivability.
 Precise metering of fuel to each cylinder and
increased air flow can result in more horsepower
output.