What primary function does the EFI computer serve in an engine's fuel system?

The EFI (Electronic Fuel Injection) computer's primary function is to determine the amount of fuel entering the engine. This process is critical for ensuring that the engine receives the right quantity of fuel for combustion, which in turn optimizes performance, fuel efficiency, and emissions. The EFI computer uses various sensors that measure factors such as air intake, engine temperature, and throttle position to calculate the appropriate fuel-air mixture. By making real-time adjustments based on these conditions, the EFI ensures that the engine operates under optimal conditions, improving overall efficiency and reducing potential issues related to under or over-fueling.

The other functions mentioned, such as circulating coolant or regulating oil flow, while important for engine operation, do not pertain directly to the fuel delivery system, which is the specific role of the EFI computer. It is essential for the EFI to manage fuel precisely in modern engines, as improper fuel management can lead to performance issues and increased emissions.