Corsica V6-173 2.8L (1987)
2. The coolant temperature sensor is above a specified temperature.
3. A specific amount of time has elapsed after starting the engine.
The specific values for the above conditions vary with different engines, and are stored in the memory calibrator (Mem-Cal) portion of the ECM. When
these values are met, the system goes into "Closed Loop" operation. In "Closed Loop," the ECM calculates the air/fuel ratio (injector "ON"-time) based
on the signal from the O2 sensor. This allows the air/fuel ratio to stay very close to 14.7:1.
Starting Mode (Port and TBI Injection)
When the ignition is first turned "ON," the Electronic Control Module (ECM) turns "ON" the fuel pump relay for two seconds and the fuel pump builds
up pressure. The ECM then checks the Coolant Temperature Sensor (CTS) and Throttle Position Sensor (TPS) and determines the proper air/fuel ratio
for starting.
This ranges from 1.5:1 at -36°C (-33°F) to 14.7:1 at 94°C (201°F) running temperature. The ECM controls the amount of fuel delivered in the starting
mode by changing how long the injectors are turned "ON" and "OFF." This is done by "pulsing" the injectors for very short times.
