I installed a BOV on my 535i a couple weeks ago. It keeps opening under acceleration, around 2500 RPM, causing a loss of boost.

I've replaced the hose clamps, gasket, put a constant torque clamp around the throttle body, and changed the spring in the valve.

I'm only running a JB+ tuner, and intake, so I'm not running any more boost than it should handle. I can't seem to fix this problem at all. Any ideas?

 

I'm curious... With factory turbos and a JB+, why the need for a BOV? You shouldn't be running a high enough boost to warrant it (even with the JB+ maxxed), and the factory BOV and charge pipe are more than sufficient for stock turbos. Did you get an aftermarket charge pipe for meth that came with the BOV? That's the only reason why you'd possibly need one. Otherwise, you could actually be hurting performance, and if not dialed in properly, there have been 135/335i instances where the BOV held too much pressure for the stock turbos and the impellers sent frags through the intake path grenading the engine! If it's working properly, this is rare, but it doesn't sound like yours is working properly. I'd recommend returning to stock!

 

I would check to make sure you have the right spring in your bov. Since it is at low boost you probably have too light of a spring allowing it to open easily. Also like what darkrider said the stock diverters are able to handle the boost. With my custom map I hit 17-19 psi regularly and dont have any issues with my diverters.