My car exhibited similar behavior when I was running a BOV. The BOV can affect the way the car drives because it is venting to atmosphere a portion of the pre-measured volume of air the ECU expects to go through the engine.

I liked the sound of the BOV, but the lack of actual benefit and the degradation of vehicle feel led me to take the unit off and sell it.
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you can take it off, of you can get one that has a dual vent...I have the GFB and it is a dual vent so it vents 50% to the atmosphere and 50% back through the intake so it doesnt throw off the ecu.

-Zoeb

 

you'll still lose air thats already accounted for if you use the 50/50 setup, just not as much.

yes, the problem can be corrected with some a/f tuning. the cause is the loss of air which will result in a momentary rich condition until the turbo repressurizes the intake tract.

 

thats true, but it is not AS BAD with a 50/50....the only real way to take care of it would be something that vents back 100% and 0% to the atmosphere like the stock one...

 

well, with an externally venting bov, the car will run rich.

... plus, he probably liked the "new sound" and drove the car more aggressivly so he could listen to his new toy.


oh, and GFB bov have teh suck. They have no adjustability and Open partially when they shouldn't, ... that sucks when you're autoxing or racing.

 

it's really hard to say. It could have been b/c the car is going to run richer with a bov like that, ... but that seems like a mighty excessive loss in mpg.
I never saw that much of a loss until after a turboback exhaust, intake, and mbc were installed.
What mods does he have?

 

hmm, don't really know what to say, ... except, since it is easy to take it on and off, ... take it of and see if it's what caused the drop in mpg.