Orifice Tube Assembly
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Orifice tube assembly is the section of tubing connecting exhaust system to intake manifold. Orifice tube provides a flow path for exhaust gas to intake manifold. The orifice tube contains a metering orifice and 2 pressure pick-up tubes. See Fig 1. The metering orifice creates a measurable pressure drop across it as EGR valve opens and closes. The pressure differential across the orifice is picked up by DPFE EGR sensor which provides feedback to PCM.