Manufacturers apply techniques to get more power and efficiency out of an engine. Adding more air into the combustion chamber (boost pressure) increases the volumetric efficiency. Via software, the correct amount of fuel can be adjusted to match the volumetric efficiency. This results in more energy, and therefore more torque. When we increase the volumetric efficiency and the fuel injection, we are tuning. The techniques that contribute to this optimization are shown in this overview.
If the fuel quantity is incorrect in relation to the amount of air, we speak of a mixture that is too lean or too rich. Fuel trims form a correction factor on the base amount of injected fuel. Fuel trims are generated and used by the engine management system.