Open Loop

When the engine is in the open loop mode of operation, the air/fuel mixture ratio will be based on a predetermined value that is dependent on several engine operating factors.

• Cold Weather Start-Up & Operation  - If the air cleaner air temperature is below the calibrated value of the TES (55°F), the air/fuel mixture is rich. Lean air/fuel mixtures are not permitted for a preset time after cold weather start-up.
• At or Near WOT Operation (Cold Engine)  - Whenever the temperature of the CTS is below 95°F and the WOT switch is closed, because of the decrease in manifold vacuum, the M/C solenoid provides a rich mixture for cold engine operation at wide open throttle.
• At or Near WOT Operation (Warm Engine)  - Whenever the temperature of the ECTS is above 135°F and the WOT switch is closed, because of a decrease in engine vacuum (less than 3 in. Hg), the M/C solenoid provides a rich mixture for warm engine operation at wide open throttle.
• Adaptive Mode of Operation  - This mode of operation occurs when engine is either at idle speed, accelerating from idle speed or decelerating to idle speed. During this mode of operation a check of all sensors is made by the MCU. If the operating values of the sensors do not agree with one another, the MCU uses a predetermined value to maintain proper engine operation. During the adaptive mode of operation, the M/C solenoid provides a predetermined air/fuel mixture.