Open Loop

When engine is first started and it is above 400 rpm, system goes into "open loop" operation. In "open loop". ECM ignores signal from O2S and calculates air/fuel ratio based on inputs from ECT sensor and MAP sensor. The ECM stays in "open loop" until the following conditions are met:

• The O2S has a varying voltage output, showing that it is hot enough to operate properly.
• The ECT sensor is above a specified temperature.
• A specific amount of time has elapsed after starting engine.