The document discusses multipoint fuel injection (MPFI) systems as an improvement over carburetors. MPFI systems inject fuel directly into engine cylinders and are controlled electronically by an engine control unit (ECU) to provide optimal air-fuel ratios under varying driving conditions. This leads to better engine performance, emissions control, fuel efficiency, and drivability compared to carburetors. The key components of an MPFI system are the air intake, fuel delivery, electronic control, and emission control systems.

1. 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

2. History & Development
• Herbert Akroyd Stuart developed the first mpfi
system
• The first use of direct gasoline injection was on
the Hesselman engine invented by Swedish
engineer Jonas Hesselman in 1925
• One of the first commercial gasoline injection
system developed by Bosch and introduced in
1952 on the Goliath GP700 and Gutbrod Superior
600

3. Basic Concept
• MPFI is an intelligent way of doing what a
carburetor does.
• In this system each cylinder has injectors to
spray the fuel/air charge into the cylinders.
• The fuel and air are mixed in what is called the
intake manifold.
• In MPFI, each injector in controlled by the
ECU(Electronic Control Unit)

4. • The ECU monitors various engine parameters
and accordingly decides just how much fuel is
to be injected into the cylinder and at precisely
what time .
• This system also allows each cylinder to be
controlled independently

5. 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

8. Type Of MPFI Systems
• The various types of MPFI systems are:
1.Simuntaneous: Together in all the
cylinders.
2. Sequential: Direct injection into the
individual cylinders against their power
strokes.
3.Group: In cylinder pairs [in V engines]

9. • Choosing the correct technique according to
the engine configuration results in:
- better power balance between cylinders
- higher output from each cylinder
- faster throttle response
• Of these technologies, sequential gives the best
combination of power balance and output in
inline 4 cylinder engines.

10. 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.
(2)Vibration from the engine equipped with this
system is less, due to this the life of engine
components is improved.
(3) No need to crank the engine twice or thrice
in case of cold starting as happens in the
carburettor system.

11. (4) Immediate response, in case of sudden
acceleration / deceleration.
(5)Since the engine is controlled by ECU, 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.
(6) The mileage of the vehicle will be improved.