Starting Mode

When the ignition is first turned ON, the ECM energizes the fuel pump relay for 2 seconds. This allows the fuel pump to build pressure in the fuel system. The ECM calculates the air/fuel ratio based on inputs from the engine coolant temperature (ECT), the barometric pressure (BARO), mass air flow (MAF), and throttle position sensors. The system stays in starting mode until the engine speed reaches a predetermined RPM.