ECU (Engine Control Unit) Cars,ECM,Parts,Functioning

ECU or ENGINE CONTROL UNIT   is the brain of the engine that controls all the functioning of the engine. It serves several functions which includes regulating and maintaining the amount of fuel and air in the fuel injection part and helps in increasing horsepower of the engine.

ECU (Engine Control Unit) Cars, ECM, Parts, Functioning

If any problems occurs in the electrical part or in any other part of your automotive than you must check your ECU. After all you don nota risk related to your car functioning. And that is the reason which makes it most important part in Automotive.

ECU Engine control unit. (Image

ECU Engine control unit.

The main function of ECU or Engine Control Unit is the  controlling of  series of function of actuators on an internal combustion engine and ensuring the excellent engine performance. The Engine Control Unit is also called Power train control unit.

Within the Engine Bay ECU takes the values from A multitude of sensors and then interpret that data by using multidimensional Performance maps  And in this way adjust the engine actuators accordingly.
This is also responsible for the best Engine performance. Engine Control Module or ECM is the same as Engine Control unit the difference is that if we named overall combined section of  control unit in engine then we called it as  Engine Control Module or ECM.

Also Read:CRDi Common Rail Direct Fuel Injection System

Working of ECU

ECU is the integral part of EFI or Electronic Fuel Injection(a type of fuel injection system commonly used among cars).Electronic Fuel Injection can be divided into sub-systems namely Air induction system , fuel delivery System and the electronic control system. And from here the function of the ECU starts.

Functioning of Engine control unit (image

Functioning of Engine control unit


Functioning of ECU

Controlling the air-fuel mixture :This is the one of the most Important function of ECU as it controls the fuel mixture used by the engine. It determines the amount of air-fuel mixture injecting into the engine. The program received the necessary data and computes it and gives the appropriate amount of mixture. It also decides whether it is the right time to deliver the air-fuel mixture in a proper ration or not. This process is also called injection duration.

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Controlling the ignition timing: ECU adjust the exact timing of the spark or the ignition timing to provide the better power and economy. ECU detects itself whether there is the problem in the compression stroke or not and works according and set the timing of ignition. This is mainly happened in the condition whenever there is unburned air-fuel mixture left and it is subjected to combination of heat and pressure .This results in detonation also known as Knocking or pinking . ECU detects the knocking and delayed the time of spark to prevent it.

Controlling on Idle speed and variable valve timing: Most cars have also built in  control system in their ECU for controlling idle speed. Idle speed is controlled through the programmable throttle stop. Apart from the controlling on idle speed ECU also controls the timing at which the valve open or close in the engine cycle. The best suitable and appropriate timing of opening and closing of valve helps in increasing the power and economy of the engine.

ECU Also Increases the Torque and BHP .As it governs the fuel injection into the cylinder,it is programmed for the efficient performance of the engine at any environment whenever ECU  encounters increase in load then it initiates a signal for more fuel injection & thus engines generates more BHP.

8 thoughts on “ECU (Engine Control Unit) Cars,ECM,Parts,Functioning

  1. racel

    hello vivek, i am your fan, i am very interested to know about CRDI most of it. i am a technician in mechanical/coventional type of diesel engine, specially in fuel system. and i want to upgrade my knowledge about CRDI. plz. help me have a copy of a book about CRDI or something just for me to learn. we had no training school here in the philippines of CDRI . please feel free to contact me soon you get my message.. thank you

    best regards

    1. Vivek Bhardwaj Post author

      Hi Racel
      CRDI-stands for Common Rail Diesel Injection. It’s a type of diesel engine, was considered to be the revolution in fuel injection system and was invented by Fiat in 1995. Fiat calls it MultiJet, and name goes on changing according to company, but technology under the hood remains the same. Hundai and Kia call it CRDI.Read More from this Article below

  2. Enock

    Hi Vivek
    I’m Enock. im also your fan. I am on IT site. I want to know this my car golf5 1.6 (petrol) is stuck. the problem was the was failing to turn. I took it to locksmith and they fixed it for me but when place it back, car doesn’t want to start. I found a car diagnosed guy and he diagnosed. No communication on ECU. that’s one of the error I got. I checked the fuse but nothing burnt. please help me.what seems to be the problem?



  3. Abhi

    Hi Vivek,
    good work… Keep it up.

    did you manage to fix the problem. I saw this website today. so came across your problem now.
    but neverthless… it sounded interesting.
    Can you please elaborate on the statement ” I found a car diagnosed guy and he diagnosed. No communication on ECU. that’s one of the error I got”. Did you get this error message on Diagnostic Testing tool ? If yes, then the tool is not able to talk to your car’s OBD connection. Either the protocol of communication is mismatching or ECU is offline.

  4. Shameem

    Hi Vivek
    I have a fiat palio diesel car 2004 two years back it was stuck in the road then I repair the ECM after that the car always stuck while running after it cool we can run it what is the problem
    Kuttichal Shameem

  5. Tejas Jadhav

    Hi vivek,
    I am a automobile engineering student I want to know more about ECU can u plz tell and explain the actual components (MICROPROCESSOR, other circuit info) of a ECU .


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