Accelerator pedal position This data is vital to the operation of the ECM and the vehicle. The ECM interprets the electrical signals from the APP sensor as throttle demand and controls the power output of the engine accordingly. Pilot Fuel Injection Pilot fuel injection helps reduce engine clatter and vibration. The ECM provides this feature by opening the electronic fuel injectors briefly, before injecting the main charge of fuel. This makes the flame front propagation through the main charge less abrupt, giving reduced levels of diesel knock.