Operating Modes Starting Clear Flood Run Acceleration Deceleration Battery Voltage Correction Fuel Cutoff
Starting Mode PCM runs fuel pump for 2 seconds PCM looks at Coolant Temp and TPS A/F Ratio varies from 1.5/1 (-32F) to 14.7/1 (201F) May have cold start injector Activated by cranking system Controlled by timer
Clear Flood Below 600 RPM 80% WOT or more A/F 20/1 or zero on 2.8-liter engine
Run Mode Above 400 RPM Open or closed loop Closed loop when O2S voltage is varying Coolant is above specified temp Time has elapsed Leaves open loop for WOT Acceleration and hard Deceleration
Acceleration Mode Rapid increase in manifold pressure or air flow Richer mixture Compensates for poor evaporation due to higher pressure.
Deceleration Mode Rapid decrease in throttle and manifold pressure Fuel is cut off completely momentarily
Battery Voltage Correction Mode Voltage drops below specified value Enrichens fuel Increases throttle opening if at idle Increases dwell to account for poor coil saturation
Fuel Cutoff Mode Ignition is turned off Distributor pulse stops Fuel is cut off Prevent dieseling Prevent fire in crash
Fuel Trim Before OBD II STFT was Block Learn LTFT was Integrator More in diagnostics
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