Electronic Fuel Injection (EFI)
June 1, 2006 by Alborz Fallah
Electronic Fuel Injection
EFI has been in European built cars since the 80s but many older cars still do not have EFI. Currently all brand new cars sold in Australia use EFI systems. Injectors are opened by solenoids operated by an electronic control unit, as opposed to mechanical injection systms. Since the fuel has no resistance to overcome, other than insignificant friction losses, the pump pressure can be set at very low values, consistent with the limits of obtaining full atomization with the type of injectors used. The control unit, depending on the operating conditions of the engine, determines the amount of fuel to be injected. The conditions depend on manifold pressure, accelerator enrichment, cold-start requirements, idling conditions, outside temperature and barometric pressure. The systems work with constant pressure and with ‘variable timed’ or ‘continuous flow’ injection. The advantages. To begin with, it has fewer moving parts, no need for ultra-precise machining standards and quieter operation. Also, there is less power loss, a low electrical requirement, no need for special pump drives, no critical fuel filtration requirements, no surges or pulsations in the fuel line. More than anything else, it costs lesser than its mechanical counterpart.
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Mechanical Fuel Injection was a step up from Carbureted engines, and EFI has been the next step forward. These days many people are converting their older carbureted engines to EFI to gain power, driveability and improved fuel economy.
Modern aftermarket engine management systems provide all three of these advantages provided they are installed and tuned correctly.
EFI does require parts to be manufactured to a very high standard, but the advantages truly outway the apparent simplicity of mechanical fuel injection systems.