Electronic Fuel Injection (ECU)

Part : I

When pollution norms goes stricter and stricter auto mobiles manufacturers are forced to change carburettor to Electronic Fuel Injection. Hero Honda was the first company who introduced Electronic Injection to their bike. After that Bajaj Introduced this system to their Pulsar 220 Model. Now Royal Enfiled also going adopt this system for their export market. Before know the working of Electronic Fuel Injection (EFI) one must know the basic components of EFI.

Sensors :

1. Mass Air Flow Sensor : Which calculate flow and density of the air which flows in to the engine through Air Filter.
2. Oxygen Sensor / Lambda Sensor : This sensor monitor the exhaust gas and calculate the amount of Oxygen in it and this data is use full to calculate fuel air mixture ratio and pollution norms.
3. Throttle Position Sensor : Which senses the Position of the Throttle and gives signal to the ECU (Electronic Control Unit) which help it to provide right amount of Fuel at right time.
   Engine / Coolant Temperature Sensor : It Monitors the Engine (Coolant in case of Liquid cooled one) temperature.
4. Engine Speed Sensor : It checks the Engine RPM (Revolution Per Minute)
5. Knock Sensor : Detects Engine Knocking

* These are only basic sensor modern machines consist various other sensors like roll over, engine malfunction, low oil level etc.

Electronic Control Unit (ECU) :
This is the brain or main component of the EFI. It gets signals from the various sensors and decides quantity of fuel, ratio of mixture and timing of Injection etc. and works accordingly. There are two sides or channels of ECU, Input and Output. In put channel collects all basic data's from sensors and process it and send output channel.

Working :

When you switch on the ignition switch on the Ignition key current flows from the battery to ECU, and from out put side of the ECU passes signals to Fuel Pump which is generally kept near or inside the tank when it get power it start to work and supplies fuel to Fuel injector thorough pressure line. At the same time Input channel of the ECU collects signals from various sensors and process it and sends out put channel accordingly. As soon as Fuel Injector get signals from the out put channel it opens and sprays right amount of fuel inside the combustion chamber, excessive fuel will return back to fuel tank via return circuit.