Electronic Control Module (ECM): Run

When engine speed is greater than 400 RPM, ECM operates in "open loop". 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". In "closed loop", ECM controls injector pulse width based upon O2 sensor signals (in addition to other input parameters) to maintain as close to a 14.7:1 air/fuel mixture as possible.