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Home >> Chevrolet >> 1985 >> Sprint Automatic >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> EGR Function Testing >> Testing >> With Modulator
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With Modulator

  1. Check vacuum lines for correct routing. Disconnect vacuum hose at EGR valve and plug hose end. Connect vacuum pump to EGR valve. Start engine. Apply 4.7 in. Hg to valve and hold.
  2. Engine speed should drop at least 100 RPM or stall. Vacuum should not drop more than 1 in. Hg in 30 seconds. Reconnect EGR vacuum hose.
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