M.P.F.I

(MULTI POINT FUEL INJECTION)

Submitted by

Prince shital

2k4/ME/266

ADVANTAGE OF INJECTION OVER CABURETION

• TO HAVE MORE UNIFORM DISTRIBUTION OF FUEL

• TO IMPROVE BREATHING CAPACITY

• TO REDUCE OR ELIMINATE DETONATION

• TO PREVENT FUEL LOSSDURING SCAVENGING IN CASE OF 2-STROKE ENGINES

MPFI

• ‘Mpfi’ stands for 'multi point (electronic) fuel injection'.

• This system injects fuel into individual cylinders, based on commands from the ‘on board engine management system Computer’ -popularly known as the Engine Control Unit/ECU.

MPFI SYSTEM

• a) ‘Sequential’ i.e direct injection into individual cylinders against their suction strokes, or

• b) ‘Simultaneous’ i.e together for all the four or whatever the number of cylinders, or c) ‘Group’ i.e into Cylinder-Pairs.

• These techniques result not only in better ‘power balance’ amongst the cylinders but also in higher output from each one of them, along with faster throttle response. Of these variants of Mpfi, 'Sequential' is the best from the above considerations of power balance/output.

•Mpfi Systems can either be :

FUEL INJECTOR

FUNCTIONAL DIVISIONS OF MPFI SYSTEM

• THE MPFI SYSTEM CAN BE FUNCTIOALLY DIVIDED INTO 3 MAIN COMPONENTS:

1)ELECTRONIC CONTROL SYSTEM

2)FUEL SYSTEM

3)AIR INDUCTION SYSTEM

ELETRONIC CONTROL UNIT(ECU)

• ECU IN ELECTRONIC CONTROL SYSTEM,RECIEVES SIGNALS FROM SENSORS AND DETERMINES THE OPENING TIME FOR THE INJECTOR LAND WHICH ALSO CONTROLS THE INJECTION VOLUME

MPFI-ELECTRONIC CONTROL SYSTEM

• FIRST,THE SENSORS THAT MONITORS INTAKE AIR & WATER TEMP., OXYGEN, THE STARTER SIGNAL SENDS SIGNAL TO ECU

• THEN,AIR FLOW SENSOR SENDS SIGNAL TO ECU ABOUT INTAKE AIR TEMPERTURE

• IGNITION SENSOR SEND SIGNAL ABOUT ENGINE SPEED

• ECU PROCESSES ALL THESE SIGNALS AND SEND APPROPRIATE COMMANDS TO INJECTORS TO CONTROL FUEL VOLUME TO BE INJECTED

MPFI ELECTRONIC CONTROL SYSTEM

SENSOR(input) TO COLD START INJECTOR INJECTOR(output)

AIR FLOW METER IGNITION SIGNAL

COLD START INJECTOR TIME SWITCH ECU

MPFI-FUEL SYSTEM

• FIRST,FUEL IS SUPPLIED BY THE FUEL PUMP • AT TIME OF STARTING ,COLD START

INJECTOR IS OPERATED BY COLD START INJECTOR TIME SWITCH

• THE COLD START INJECTOR INJECT FUEL INTO AIR INTAKE CHAMBER

• PRESSURE REGULATOR REGULATES THE PRESSURE OF THE FUEL

• INJECTOR RECEIVE SIGNAL FROM ECU AND INJECT FUEL INTO INTAKE MANIFOLD

MPFI-FUEL SYSTEM

FUEL FUEL PUMPFUEL COLD START

COLD START INJECTOR

PRESSURE REGULATOR

INJECTION SIGNAL FROM ECUCONTROLLING FUEL INJECTION VOLUME

INJECTORS

INJECTOR TIMING

INJECTIONINTO INTAKE MANIFOLD

MPFI-AIR INDUCTION SYSTEM

• AIR CLEANER,AIR FLOW METER , THROTTLE BODY AND THE AIR VALVE SUPPLY A PROPER AMOUNT OF AIR TO AIR INTAKE CHAMBER AND INTAKE MANIFOLD

MPFI-AIR INDUCTION SYSTEM

AIR CLEANER

AIR FLOW METER THROTTLE BODY AIR VALVE

AIR INTAKE CHAMBER

CYLINDERS

FROM COLDSTART INJECTOR

INTAKE MANIFOLD

INJECTION FROMINJECTORS