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Old 01-26-2015, 10:29 PM   #87 (permalink)
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TDi - '04 VW Golf
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Quote:
Originally Posted by mwebb View Post

The current VW TDi (diesel) system does use a throttle body type flap near the center of the exhaust to increase exhaust pressure to assist EGR at various times as determined by the ECM and the current VW TDi does have a throttle body type flap in the intake, again it is controlled by the ECM and part of it's function is to assist with EGR. Both of these "throttle body" type flaps are drive by wire, there are no "throttle cables" or any mechanical connections to them, the ECM has control using little motors with position sensors on the flaps. The EGR gas flows from a higher pressure area to a lower pressure area as assisted by the ECM
Could this account for increased mileage with an EGR tune in a VW?
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Quote:
Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
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