MPFI

(Multi Point Fuel Injection)

Done By

MUKUL

R0ll no:44

Introduction

• In petrol vehicles carburetor is used for supplying air fuel mixture to the cylinder

• In response to the recent demand for cleaner exhaust emission improved drivability and mileage carburetor is not sufficient

• In place of the carburetor MPFI system is used in vehicles

• MPFI system is injects fuel into individual cylinders based on commands from engine control module

• The MPFI gives higher output, faster throttle response under varying driving conditions

Components of MPFI

• The system has four major components they are

1. Air intake system

2. Fuel delivery system

3. Electronic control system

4. Emission control system

• Air intake system

• It includes air filter, throttle body, intake

manifold, and finally drawn into the combustion

chamber

Air intake system

• Throttle body

• It consist of throttle valve, T P sensor, which detect the throttle valve opening

• Idle air control valve which supplies bypass air depending on the engine condition

• Fuel delivery system • It includes fuel pump, fuel filter and injector

• Fuel pump

• ECM controls its operation and centrifugal pump is used to pump the fuel

• The fuel pump also has a check valve to keep some pressure in fuel feed line even when fuel pump is stopped

Pressure regulator system

• It keep the fuel pressure applied to the

injector 2.9kg/cm^2

• Injector

• Each cylinder have one injector

• It inject the fuel into the inlet manifold according to

the signal from ECM

• Electronic control system• The electronic control system consist of various

sensors which detect the state of engine and driving

conditions

•

Control systems are,

• Fuel injection control system

• In which ECM controls the timing of fuel

injection according to the signals from

various sensors

• Injection time is calculated on the basis

of engine speed

• Idle speed control system

• It keep the engine idle speed as specified

at all times

Fuel pump control system

• ECM controls the ON\OFF operation of

the fuel pump

• Ignition control system

• This system controls ignition timing

• The ECM judges the engine conditions

by using signals from various sensors

selects suitable ignition timing

• Controls of this system includes

• Ignition timing at the engine start

• Ignition timing after engine start

Radiator fan control system

• Radiator fan motor is turned ON and OFF by using

relays

• Radiator fan motor turned ON at below 98degree

Celsius and OFF at below93degree Celsius

• Engine Control Module • It consist of micro computer, analogue\digital

converter

• It controls fuel injector, IAC valve, fuel pump relay

….etc

•

Working

Functional division of MPFI

On-board diagnostic system

• ECM diagnosis troubles which may occur in the engine

when ignition switch is ON and the engine is running, it

indicates trouble to the driver by flashing malfunction

indication lamp

• And it stores the data about the trouble in ECM back up

memory

• Emission control system• It includes evaporative canister

• Evaporative emission control system• This is used to prevent emission of fuel vapour

Sensors used in MPFI

• Manifold absolute pressure sensor

• This sensor senses pressure change in the intake manifold

• The signals from the MAP is used by the ECM to control fuel injection pressure

• Throttle position sensor• This is connected to throttle valve shaft on the throttle

body and detects throttle valve opening

• Intake air temperature sensor

• It located on the air cleaner outlet hose and constantly measures the temperature of air entering to the intake manifold

• By sensing the temp. the ECM adjusts fuel injection

quantity

Engine coolant temperature sensor

• It is incorporated with coolant and measures the

coolant temperature

Oxygen sensor Oxygen sensor is installed on the exhaust manifold

to detect the concentration of oxygen in the exhaust

gases

It is necessary to keep the air fuel ratio within a

narrow range, and keep it in a stochiometric air fuel

ratio

Vehicle speed speed sensor

The vehicle speed sensor is located on the

transmission gear box or speedometer

Cam shaft position sensor

• Using this signal ECM identifies cylinder whose

piston is in the compression stroke

• Crank shaft position sensor

• ECM uses this signal for knowing the engine

speed and cylinder identification

Advantages of MPFI

• 1) More uniform A/F mixture will be supplied to each cylinder; hence the difference in power developed in each cylinder is minimum. Vibration from the engine equipped with this system is less, due to this the life of engine components is improved.

(2) No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system.

(3) Immediate response, in case of sudden acceleration / deceleration.

Advantages of MPFI

• Since the engine is controlled by ECM* (Engine Control Module), more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level.

(5) The mileage of the vehicle will be improved.

Conclusion• Almost all vehicles in India are changing to

the MPFI because of law emissions, improved mileage and drivability

• Since the engine is controlled by micro computer more accurate amount of A/F mixture will be supplied and as a result complete combustion will take place. This leads to effective utilization of fuel supplied and hence low emission level.

• It reduces wastage of fuel by the use of sensors and other control systems