Electronic Control Module (ECM): Run

When engine is running above 400 RPM, ECM operates in Open Loop Mode. In open loop, ECM calculates injector pulse width based upon coolant temperature and Manifold Absolute Pressure (MAP). Engine will remain in open loop operation until O2 sensor reaches operating temperature, coolant temperature reaches preset temperature, and a specific period of time has elapsed after engine starts. When all these conditions are met, ECM operates in Closed Loop Mode. In closed loop, ECM controls injector pulse width based upon O2 sensor signals to maintain air/fuel mixture ratio close to 14.7:1.