I took my BPV (bypass valve) off and noticed that when it was closed I could see light around the blade. Is this normal condition and is the BPV adjustable

 

Yes and Yes.
it's normal due to batch assembly of a part
You can correct it by loosening the butterfly plate set screws and adjusting the plate.
A little Loctite on them wouldn't hurt.

 

Yep pretty normal, but like he said adj the stop screw and usually you can make it close a bit more.

 

Is this a noticeable gain/ effect? How much boost we talking? Worth adjusting it? Or is this more of an OCD thing?

 

Probably more of an OCD thing, but it really depends on how far off it is and how much air is escaping around that butterfly.
​​​​​Honestly, it really depends on you and your situation, it's very easy to do, but the BPV has to be removed, so is it still off? Or how difficult do "you" think pulling the BPV is, and/or is it going to be off again for some reason.

 

well said. That’s what i was hoping for Thank You

 

Can this cause an error code P1498?

 

Yes, but not because of a misaligned butterfly.
It would have to be a mechanical or vacuum failure associated with the BPV or it's connections.

 

I have looked at the BPV and when the motor is off the plunger arm is fully extended. When the motor is running at idle the plunger arm is fully retracted. At any rpm up to 5k the arm stays retracted and when you take your foot of the gas and the motor goes back to idle nothing changes. The plunger arm is always retracted when the motor is on. This does not seem right to me

 

Can anyone tell me how the BPV should work

 

Basically:
Open under vacuum / Closed under boost
So the amount it's open will vary as you drive.

I suspect you did the above test while stationary, this is why you got the results you did, you won't build boost without some kind of resistance, ie. In gear, driving or brake torqueing.

You can drive the car with it temporally zip tied in the closed position, that may help you determine if it's your issue or not.

 

 

Soooooo my yoyo could be caused by a weak spring in my bypass? I'm also only making 11lb of boost with 15% pulley. No drivability issues or codes but it yoyos bad at 10mph or under and I feel like it should be making more boost too.
sorry to hijack

 

I did the BPV test while stationary. I will hook up my GoPro to see if it working while I drive the car

 

Possibly, the yoyo in the pre-facelift cars is why Chad offers the DT BPV.