what is MPFI ? and how does it works??

        Ø  MPFI is nothing but "Multi Point Fuel Injection"

  

        Ø  “Frederick William lanchester” who invented the earliest
   MPFI engine.

       Ø      This system consists of sensors which are connected to the ECU (Electronic Control Unit).

  

       Ø  The function ECU is to analysis the sensor signal according to that signal injection is done in the combustion chamber.

  

  Ø ^{Generally the MPFI system consist of sensors like}

ü ^{Air flow sensor (AFS)}

ü ^{Throttle Position Sensor (TPS)}

ü  ^{Water Temperature Sensor (WTS)}

ü  ^{Intake Air Temperature Sensor (IATS)}

ü  ^{Engine Ignition Signal Sensor (EISS)}

ü  ^{Starter Signal Sensor (SSS)}

ü  ^{Oxygen Sensor (OS)}

ü  ^{Cranks Shaft Position Sensor (CSPS)}

ü  ^{Vehicle speed Sensor (VSS)}

 MPFI system can be divided into two types,             

According to the method used in sensing the volume of intake air.

 Ø D-MPFI (Manifold Pressure Control Type)

§  This type measure the vacuum in the intake manifold and senses the volume of air by its density.

§  D-MPFI is refrred to as D-jectronic, which is the trade mark of Bosh.

§   D-jectronic is a word created from german Druck (Pressure) and jectronic is a word coined by meaning “injection"

Ø L-MPFI (AIR FLOW CONTROL TYPE)

§  This type directly senses the amount of air flowing into the intake manifold by means of air flow meter.

§  L-MPFI referred to as L-jetonic

§  “L” comes from german Luft (AIR)

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 WORKING OF MPFI

§  When the ignition swithch is swithched ON, the electrical supply from the battery is passed to all the sensors,ECU(Electronic Control Unit),fuel pump and starter motor.

§  When the engine starts cranking, the starting motor signal sensor is activated and sends sinal to the ECU.

§  Now fuel to the engine is increced to start the engine easier.

§  Then throttle position sensor is activated by the ECU and the throttle valve is opened according to the acceleration and engine temperature.

§  Engine ignition signal sensor analyses the signal and spark is produced at correct timing.

§  Then the pressure of oxygen in the exhast gas is analysed by oxygen sensor and signal are sent to the ECU.

§  The amount of air-fuel mixture is controlled by the ECU through throttle position sensor and air intake sensor.

§  This result in better fuel injection.

  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. 

4) 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.