Starting Mode

When ignition is turned ON, PCM/ECM turns fuel pump relay on for two seconds. The fuel pump then builds fuel pressure. The PCM/ECM also checks Engine Coolant Temperature (ECT) sensor and Throttle Position (TP) sensor and determines proper air/fuel ratio for starting engine. This ranges from 1.5 to 1 at -97° F (-36° C) coolant temperature to 14.7 to 1 at 201° F (94° C) coolant temperature. The PCM/ECM controls amount of fuel delivered in starting mode by changing how long fuel injector is turned on and off. This is done by "pulsing" fuel injectors for very short times.