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      03-23-2007, 01:31 PM   #21
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1990 325i  [0.00]
Originally Posted by n1smo View Post
I was told in another thread that the butterfly valve stays wide open after the car is warmed up because the Valvetronic takes over the tasks of what the throttle body used to do. With that said, the only gain you will see is from the throttle body being bored out by 3mm. And I don't see how it will help since it is just at the point of the throttle body, its not like the entire inlet air track was bored out by 3mm.
The Valvetronic system is the first variable valve timing system to offer continuously variable timing (on both intake and exhaust camshafts) along with continuously variable intake valve lift, from ~0 to 10 mm, on the intake camshaft only. Valvetronic-equipped engines are unique in that they rely on the amount of valve lift to throttle the engine rather than a butterfly valve in the intake tract. In other words, in normal driving, the "gas pedal" controls the Valvetronic hardware rather than the throttle plate.

It is important to note however, that the throttle plate is not removed, but rather defaults to a fully open position once the engine is running.

Pulled this from here

Makes sense to me