Manufacturers apply techniques to extract more power and efficiency from an engine. Adding more air into the combustion chamber (boost pressure) increases the volumetric efficiency. Software can adjust the correct amount of fuel to the volumetric efficiency. This results in more energy, and thus more torque. When we increase the volumetric efficiency and fuel injection, we are engaged in tuning. The techniques that contribute to this optimization are outlined in this overview.
If the amount of fuel is incorrect relative to the amount of air, we refer to it as a lean or rich mixture. Fuel trims serve as a corrective factor on the base quantity of injected fuel. Fuel trims are created and used by the engine management system.