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Home >> Volkswagen >> 1985 >> Quantum Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH Cis-E >> Testing >> Electrical Components >> Idle Speed Boost Valves
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Idle Speed Boost Valves

  1. To test boost valve I, engine oil temperature must be at 176°F (80°C) minimum. If equipped, A/C must be off. Run engine at idle speed. Turn on all electrical units except A/C. Turn in idle speed adjusting screw to lower idle. At 750 RPM, boost valve I should open and idle speed will increase.
  2. Pinch outlet air hose shut after "T" connector. Engine speed should drop. Leaving air hose pinched shut, raise engine idle speed to 870-930 RPM. Open air hose. Idle speed should increase. When 1050 RPM is reached, boost valve I should close and engine speed should drop to 870-930 RPM.
  3. To check boost valve II (A/C equipped only), make sure A/C is off. Run engine at idle speed and pinch outlet air hose shut. Engine speed should not change. When A/C is switched on with air hose pinched shut, idle speed should drop.
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