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Lambda Control

  1. Engine oil temperature should be 176° F (80° C). Engine should be idling at 700-800 RPM. Check on/off ratio. If reading is between 40-60%, system is working correctly and test is complete. If reading is below 40%, above 60% or constant 50%, adjust mixture to obtain 45-55% on/off ratio.
  2. If mixture cannot be adjusted to get correct ratio, check that thermo vacuum valve rated 122°F (50° C) is open. If valve is open, replace ECU. If mixture ratio stays at constant 50%, replace defective O2 sensor.
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