est How do ECUs, PCMs, and ECMs Work? These control modules receive input from various sensors throughout the vehicle, such as the throttle position sensor, oxygen sensor, and mass air flow sensor. They use this information to make real-time adjustments to fuel injection, ignition timing, and other critical functions to optimize performance and efficiency. The ECU controls the engine’s functions, including fuel injection, ignition timing, and emissions. It gathers data from sensors throughout the engine and makes real-time adjustments to optimize performance. Issues with the ECU can cause poor fuel efficiency, decreased power, and increased emissions. PCM (Powertrain Control Module) …