Adventures Under the Hood

Sequence of Events at Startup

• Cold Startup

  • Thermal Electric Switch in the air cleaner is closed.
  • Coolant Temperature Switch is open.
  • Metering Pins in carburetor initialize.
  • Manifold Heater Switch is closed.
  • Oil Pressure Switch closes....
    • Manifold Heater relay is energized.
    • Electric Choke relay is energized.
  • MCU controls timing.



• Warmup

  • MCU operates "Open Loop," controlling only the timing.
  • Thermal Electric Switch in the air cleaner opens at 65°.
  • Coolant Temperature Switch closes at 135°.
  • Manifold Heater Switch opens at 160° , turning off the manifold heater.



• Normal Operating Temperature

  • Once the Thermal Electric Switch opens and the Coolant Temperature Switch closes, the MCU goes into "Closed Loop" mode, taking control of the carburetor, Pulse-Air System, and Idle Solenoids, and listening to input from the O2 Sensor and other devices.

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