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Home >> BMW >> 1979 >> 633CSi Automatic Trans >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Exhaust Gas RECIRCULATION >> Testing >> EGR Valve >> 630CSi, 633CSi & 733i
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630CSi, 633CSi & 733i

  1. With engine idling at normal operating temperature, disconnect Blue hose from EGR valve. DO NOT plug hose or connection. Engine speed should not change.
  2. If speed drops, either the EGR valve is defective, idle position of throttle is out of adjustment, or the Red vacuum hose from throttle housing is leaking or plugged.
  3. Disconnect Blue hose from EGR valve. Pull White hose from connection on intake manifold. Pull Red hose from throttle housing and connect it to fitting from which White hose was removed.
  4. Engine speed should drop considerably. If not, EGR valve is defective, temperature switch is defective, or the Red electromagnetic switching valve is defective.
  5. Reconnect Blue hose to EGR valve. Leave Red hose from throttle valve housing connected to intake manifold fitting from which White hose was removed. Engine speed should drop slightly. If there is a large drop in engine speed, there are faulty vacuum hoses, a defective EGR valve, or defective pressure transmitter.
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