What does EFI stand for?Electronic fuel ingnition
Who invented fuel injection and when?
Herbert Akroyd Stuart was the first to come up with the idea at the end of the 19th century and they were used on hot bulb engines. Which is an engine in which fuel is ignited by being brought into contact with a red hot metal surface inside a bulb. The first use of direct gasoline injection was on the Hesselman engine invented by Swedish engineer Jonas Hesselman in 1925. Hesselman engines use the ultra lean burn principle; fuel is injected toward the end of the compression stroke, then ignited with a spark plug.
Explanation of how the following components work....
Fuel rail
Fuel pressure regulator
This component is used to keep the pressure of fuel in the fuel rail at a certain pressure. It is controlled by the diaphram so when there is to much pressure the extra fuel will be dumped back into the fuel tank. Here is a short video on how to test fuel pressure and looking at the regulator etc. http://www.youtube.com/watch?v=ERZe6Vrl7toIdle air control (IAC)
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars ECU receives information from various sensors and will output signals to adjust the idle air control motor in or out to adjust engine idle speed by controlling engine idle air.
Injectors
http://www.youtube.com/watch?v=eVCYR4B7IZ8&feature=related this video here is a basic video of the operation of the injectors. The fuel injector itself is just a high speed valve for fuel. Fuel injectors are normally fed power whenever the ignition key is on. The computer controls the ground of the circuit. When the ECU provides the injector with a ground, the circuit is completed and current is allowed to flow through the injector. This energizes an electromagnetic coil inside the injector, which pulls the pintle away from its seat. This makes it possible for fuel to flow through the injector and into the engine. When the computer removes the electrical ground to the injector, the electromagnetic coil becomes demagnetized and a spring forces the pintle shut to cut off fuel flow.Lambda sensor (O2 sensor)
The use of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible. Its been worked out that there is a particular ratio of air and fuel that is "perfect" and that ratio is 14.7:1. If there is less air than this perfect ratio, then there will be fuel left over after combustion. The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage. The ECU looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine acordingley.
Manifold absolute presure sensor (MAP sensor)
The MAP sensor is a main input to the ECU. The MAP sensor measures the difference in air pressure between the intake manifold and atmospheric pressure which is provideding instantaneous manifold pressure information to the engines ECU.Camshaft sensor and crankshaft sensor
The cam sensor tells the ECU which stroke number one piston is on so it knows which cylinder to fire or inject fuel into.The crank sensor can only send a signal telling the ECU that number one piston is at TDC but it cant tell it which stroke could be compression or exhaust.The cam position sensor on some common rail diesels only gives out a pulse while the engine is being cranked as once the ECU knows the position of number 1 piston and its reference point to cam position it shuts the cam sensor down as it doesn't need a reference signal to maintain the correct firing order.
Plenum chamber
It is located between the throttle body and the runners of an intake manifold, used to distribute the intake charge evenly and to enhance engine breathing.
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