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dmckmc dmckmc is offline
Junior Member
Posts: 272
Join Date: Oct 2017
Car: E60 535i
Default 09-17-2020, 04:33 PM

First thing is first: The purpose of the spring in a BOV IS NOT to hold your BOV closed under boost pressure!

All BOVs have a reference line coming into the top of the BOV from your post-throttle body intake manifold. Under high boost, the force holding the BOV closed is BOOST! The pressure coming through the reference line is equal to the pressure under the BOV piston. Therefore a VERY mild spring will hold it shut just fine under these conditions.

Rather, the purpose of the spring in a BOV is to hold the BOV closed when your throttle plate is closed, IE during idle and deceleration conditions.

Therefore, your goal when selecting a BOV spring and adjusting the BOV should NOT be to select a spring based on your boost level; that makes no sense. Your goal is to get the BOV to stay CLOSED during high intake manifold vacuum/closed throttle plate conditions, using the very smallest amount of spring energy possible. Using less spring energy will allow the BOV to snap open as rapidly as possible when pressure release is necessary.

Second: where are your logs? Really can offer little support without them, it would be pure speculation. Also best to post logs and support questions in the N54 Support & Log Review sub forum.


Last edited by dmckmc; 09-17-2020 at 04:58 PM..
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