Starting Mode

When the ignition is turned ON, the ECM turns the fuel pump relay on for two seconds. The fuel pump then builds fuel pressure. The ECM also checks the Engine Coolant Temperature (ECT) sensor and the Throttle Position (TP) sensor and determines the proper air/fuel ratio for starting the engine. This ranges from 1.5 to 1 at -97°F (-72°C) coolant temperature to 14.7 to 1 at 201 °F (94 °C) coolant temperature. The ECM controls the amount of fuel delivered in the starting mode by changing how long the fuel injector is turned on and off. This is done by "pulsing" the fuel injectors for very short times.