Open Loop

When the engine is first started, and engine speed is above 637 rpm, the system goes into Open Loop operation. The ECM ignores the signal from the oxygen sensor, and calculates the fuel required based on inputs from the Engine Coolant Temperature (ECT) and Mass Air Flow (MAF) sensors. The system stays in open loop until the following conditions are met:
1. The oxygen sensor has varying voltage output, showing that it is hot enough to operate properly. (This depends on temperature.)
2. The Engine Coolant Temperature (ECT) sensor is above a specified temperature.
3. A specific amount of time has elapsed after starting the engine.