Engines in today’s cars are controlled by computers known as engine control units or ECU’s. These ECU’s control all aspects of the motor’s operation, including ignition, timing, fuel delivery and spark. They are programmed to deliver a specific balance of air and fuel to the motor. This balance is also known as the air/fuel ratio (a/f ratio) When the motor is modified with upgraded components such as larger injectors, bigger turbo, cams, boost level, air fuel meter, the stock ECU is unable to maintain the proper air fuel ratio. A lack or overabundance of air or fuel will blow the motor. To prevent this from happening, aftermarket companies also manufacture ECU upgrades to allow the motor to run with the upgraded components and provide the proper a/f ratio and ultimately increase horsepower, torque and overall performance.
There are 2 types of fuel computers: Piggyback and standalone. Piggyback fuel computers only control ignition timing and fuel delivery. The stock ECU controls all other functions of the motor. Standalone fuel computers are a "plug and play" setup where you replace the stock ECU with the aftermarket ECU. The after market standalone controls all aspects of the engine.
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