I am asking this in the Northwest section because I know a lot of you and need some help fast. I have a hillclimb this weekend and need to get it figured out by Friday around noon at the latest.
Here is my problem.
I have been running a Perrin BOV for a while now. But when I go up in elevation it starts to buck the car when I try to feather the throttle. So I got a stock BOV to put on the car hoping it would help. The stocker flutters really loudly and sounds like an external wastegate venting to atmosphere between shifts. When I was up in the hills yesterday it was leaking when I was part throttle or trying to feather the throttle. I found another stock one to try and it is doing the same thing. I am sure it is hooked up correctly. And all the vacume lines are not kinked. The car runs fine except the BOV leaking and fluttering. So if you have any idea what it is or know how I can fix it please let me know. I just put the Perrin BOV back in until I get it all figured out. Thanks in advance

 

I forgot to mention that the BOV is recirculating. It sounds like the plunger in the BOV is going nuts.

 

did you check for any other boost leaks?

 

Yes I did check for boost leaks and found nothing. It is holding boost fine also.

 

Hate to make you sound like a dummy, but are you sure it's not on backwards? The symptoms you describe sound like when people install them backwards.

 

Thanks, I will flip it around tomorrow and try it. I looked at a picture here on EvoM to see what way it went. Maybe it was backwards in the picture. I now can't find that picture lol.

 

I am not sure where the hill climb is. But if your traveling north I would be willing to take a look at it.

In my experience a fluttering BOV is usually a vaccum leak or the hose is collapsing under vaccum. I have seen this many times. Cheap vaccum lines can break down to the point that they collapse and the BOV desn't see the vaccum.

I use fuel line for all BOV, wastegate lines on my shop car.


If it works fine at lower elevations something else to consider is at high altitude your car doesn't pull as much vaccum as at sea level. I have had BOVs that had to have the springs adjusted so the lower vaccum can overcome the spring.

 

Are you in boost when this happens? When you say you're feathering the throttle, wouldn't any bit of backing off of the throttle actuate the bov. Continuously doing this would make this flutter or leak as you refer to it. I would think this would happened most right at neutral between boost and vacuum. Just stay on the skinny pedal! Problem solved! Ha ha!

 

Well if it's not on backwards there is your answer!

 

If you are feathering the throttle a bunch this will cause the BOV to open and close. To help reduce this from happening try adjusting the Perrin BOV tighter by screwing down the top. If you hit the stop you will have to open up the BOV and adjust the stopper down more. Let me know if this helps some, but it wont make it go away altogether.

JohnL

 

Thanks everyone. The stock BOV was on backwards. It works awesome now. It is very quit and works very well. I went and test drove it in higher elevations today and was able to feather the throttle around the curves. Drives so much better than the Perrin one.

And thanks John. I had Jeff Perrin look at it and he said everything was fine with it. I adjusted the Perrin BOV many times and had a shop try also, but it never would do what I wanted it to do. It was great for being loud(even full recirculated) and the drag strip. But I am now in to autocross and hill climbs and it doesn't do to well for that.