Modes Of Operation: Run

When engine is started and RPM is above 400, the system goes into open loop operation. In open loop, ECM will ignore oxygen sensor signals and compute air/fuel ratios based on input from coolant and MAP sensors. Injector "ON" time is not synchronized with HEI distributor reference pulses during open loop.

System will remain in open loop until: oxygen sensor reaches operating temperature, coolant sensor is above a specified temperature, and a specific amount of time has elapsed since starting the engine. When these conditions are met, system goes into closed loop.

In closed loop, ECM will compute air/fuel ratio (14.7:1) based on input from oxygen sensor. The ECM will deliver an injector pulse for each distributor reference pulse received. In either mode, injectors are pulsed alternately for each distributor reference pulse.