Open Loop

When the engine is first started and engine speed is above 637 RPM, the system goes into Open Loop operation. Also, when the engine is first started and the throttle position has not changed, the system remains in Open Loop until the throttle is moved. When the system is in Open Loop operation, the PCM ignores the signal from the O2S and calculates the air/fuel ratio based on inputs from the Engine Coolant Temperature (ECT) and Manifold Absolute Pressure (MAP) sensors. The system stays in Open Loop until the following conditions are met:
^ The O2S has varying voltage output, showing that the O2S is hot enough to operate properly. This depends on temperature.
^ The ECT sensor is above a specified temperature.