ECU- Electronic control unit
The ECU is the brain of the modern engine which uses lots of sensors to know what the engine is doing at all times and its job is to read this information and make the correct changes to the engine. The ECU is just a computer with inputs from sensors and actuators to control what is going on. If this component is damaged the car wont run or perform normally.
Mass air flow sensor
The MAF sensor is used to know the mass of air that is entering the intake at all times and tells the ECU through the changing of voltages as air passes it. The ECU then looks at these reading and knows whether to add more or less fuel to the engine. There are two types of MAF sensors one is a vane type which moves a diaphragm inside and the other uses a hot wire to determine the amount of air.
Intake air Temperature sensor(IAT)
The air temperature sensor is inside the intake and measures the heat of the air that’s that’s passing it. As it heats the resistance drops which tells the ECU which makes changes to the air/fuel mixture when needing to.
The throttle position sensor is on one side of the throttle butterfly and changes its voltage as the throttle moves so that the ECU knows where the throttle is at, at all times so it can make changes to the engine.
The throttle body is the part of the intake that controls how much air is going into the intake manifold at all times. It has a throttle butterfly inside it and as it turns it opens and close the butterfly. This is the main mechanical control on the engine and is mounted on the end of the intake manifold or on the carburetor.
Engine Coolant temperature (ECT)
This sensor is mounted on the by the thermostat which it reads the temperature of the coolant and tells the ECU by changes its resistance so then it can make changes to the engine performance.
A fuel rail is a rail which constantly has fuel at pressure in it to supply to the injectors which come off the fuel rail and need a constant pressure. Some fuel rails have fuel pressure regulators to control the fuel pressure. It has an inlet and most of the time a return to the fuel tank for any left over fuel.
A fuel pressure regulator is put in before and sometimes after the fuel rail which controls the pressure at a constant rate that is above the intake manifold pressure. These come in all shapes and sizes and you can get aftermarket regulators that can be adjusted if u need more or less fuel.
The injectors are positioned between the fuel rail and the cylinder head on the intake side and its job is to spray the fuel in at the correct times. The ECU tells it when to spray. This is just a solenoid controlled device that only needs a power and earth to work.
Idle air control
The idle air control valves job is to maintain a constant idle speed it is positioned on the side of the throttle body and is put in to bypass the throttle butterfly to keep a constant idle rpm this is controlled by the ECU
The oxygen sensor is positioned in the exhaust system near the exhaust manifold and it reads the oxygen content in the exhaust fumes and tells the ECU whether the engine is running lean or rich. Some cars will have two which are placed before and after the catalytic converter so it knows if the catalytic converter is doing its job.
The manifold absolute pressure sensor is put in to measure the manifold pressure at all times so that the ECU knows how much fuel to add with the air. These sensors are mainly used in engines with EFI and also to the ECU how dense the air is inside the intake manifold.
Plenum chamber
The plenum which is the intake manifold side of the engine and is used to bring in the air from the throttle body and to distribute the air evenly to all of the cylinders so that the intake valve can supply it to the combustion chambers.
The cam and crank sensors are placed on the camshaft and crankshaft and tell the ECU at all times where the cam and crank are so it knows whether it is at TDC or BDC. Some engines use these sensors to know when to distribute the spark to the cylinders. They use a magnet or pickup on the gears which tell it every time the gear moves.
Who invented fuel injection and when?
The first use of fuel injection was by a Swedish engineer named Jonas Hesselman in 1925.
What does EFI stand for
The term EFI is short for Electronic Fuel Injection
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