MULTI POINT FUEL INJECTION

SLIDE PLAN INTRODUCTION COMPONENTS OF MPFI AIR INTAKE SYSTEM PRESSURE REGULATOR SYSTEM CONTROL SYSTEM FUEL PUMP CONTROL SYSTEM WORKING FUNCTIONAL DIVISIONS OF MPFI SYSTEM ADVANTAGE AND DISADVANTAGE CONCLUSION

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 Fuel delivery system Fuel pump 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 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

Working

The MPFI system consists of one fuel injector placed near every intake valve and directed towards it, in the fuel intake manifold. Fuel is supplied to the injector through a common rail. The amount of air intake is decided by the car driver by pressing the gas pedal, depending on the speed requirement.

The air mass flow sensor near throttle valve and the oxygen sensor in the exhaust sends signal to ECU. ECU determines the air fuel ratio required ,hence the pulse width. Depending on the signal from ECU the injectors inject fuel right into the intake valve. The fuel sprayed at high pressure gets atomized into fine particles and get mixed with air. The air fuel mixture is sucked into the engine cylinder and the combustion takes place.

FUNCTIONAL DIVISIONS OF MPFI SYSTEM The mpfi system can be functionally divided into the following three main components 1. Electronic control unit 2. Fuel system 3. Air induction system

Advantage of M. P. F. I. No need to crank the engine twice or thrice in case of cold starting as happens in the carburetor system. Immediate response, in case of sudden acceleration / deceleration. The mileage of the vehicle will be improved

Disadvantage of M. P. F. I. Manifold Heat control System OR Valve is Required. Intake Manifold control only air not Fuel.

CONCLUSION The multi cylinder engines used distributors. But very shortly MPFI system replaced the distributors. The modern day cars use MPFI engines ,which has electronic control in it. They use the engine sensors, integrated chips to monitor the fuel injection time and quantity The multipoint fuel injection are also used in the engines which use LP gas as the fuel, with very less alterations in the gasoline run engine.

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