SSkull

Driving to work this morning I was going along like normal, downshifted and my BOV vented, but it sounded different in a way, can't really describe it.

So after I get off work I go to drive home and see if anything is different. Car feels fine, drives along normally, etc. The BOV vents normally at higher throttle and car builds boost like normal as well. But at wide open throttle, it just starts bleeding the boost from the BOV opening up on its own even though I'm at 100% wide open throttle. I let off right away and then you can hear the BOV still venting till it kind of tapers off and closes.

Just a normal A&A Kit installed about a year ago, with the 50MM Race Port BOV. My only other experience has been with an HKS SSQ, and Procharger Big Red on my dads C6 in the past, but neither of those ever had any issues. I pulled apart everything underneath when I got home to see if maybe a band or fitting had loosen up somewhere, but everything was very snug and tight, nothing that I can tell being the obvious issue. The BOV itself appeared to be fine, and the line attached to it didn't seem to be damaged in any way, but obviously the problem being at WOT only makes it harder for anything to show itself when I just have it sitting in the driveway opened up.

Anyone have any suggestions on how to trouble shoot this? I'm assuming the BOV failed(or vacuum line maybe?), but that's just my somewhat uneducated initial guess on why it seems to open up and stick open for a bit.

Here's a video where you can hear what I'm talking about from my drive home:

You Tube

stevieturbo

if you can see the valve mechanism opening, setup a camera or something.

But is the valve you're using actually intended for a supercharged vehicle ? and installed correctly ?

Get a mityvac and see how much vac it actually takes to open...and at the same time if there are any leaks.

SSkull

The BOV itself is one of A&A's offered units along with their supercharger kit, nothing mixed and matched brought in from outside their kit, also has been on the car for coming up on a year now without any issue at all. Entire kit has been wonderful til this little minor annoyance I gotta sort out.

The mechanism on the valve is opening and resealing just fine on neutral revs, as well as during any normal driving where I may start building boost but haven't gone wide open yet, I can roll on up to like 4k rpm go to shift up to the next gear and it'll vent off properly and quickly like it always has.

Only at wide open does it just open itself up and start venting til it does that tapering off and reseals, and it does the same way regardless of if I let off the throttle, clutch in or anything like that to bring the rpm down.

Thanks for your input, my plan was to pull it off Sunday and check the unit itself for leaks, so I'll just stick with that. Hopefully that'll give me my answer then and there.

stevieturbo

No need to remove it. just check the top chamber with a mityvac

It needs boost+spring to keep it shut. So possibly the diaphragm or something is leaking, or the line to it has an issue. Mityvac easiest way to check without taking things apart.

SSkull

Got it, thanks.

helga203

Don't know if its the same, but mine sounds just like ur and it was the seal leaking. When i took it off there was a rip on it.

SSkull

Thanks for putting your experience out there for me. Appreciate it.

~Josh

Obvious the valve has an issue.

I’d order a new one, can dissect the old and buy the one part needed for repair upon disassembly, depends on patience factor.

SSkull

Not the valve, swapped it out. Got a boost leak somewhere that I gotta track down.

Rkreigh

We need an RPM sensor in these blowers just like the high end turbos have. That way you could see if it's belt slip

Don't discount that, the belts get hard from slipping and the slipping gets worse.

I'm moving to an A&A drive with better 8 rib pulley

stevieturbo

Tick did rig up a rpm sensor, not overly difficult. Just add a ferrous metal "tooth" somewhere on the blower pulley and point a suitable sensor at it and log it on your ecu to compare to crank rpm.

Rkreigh

I'll bet my Haltech has a free input channel and that would be pretty cool!! Great idea.

sydneyACE

Did you find your boost leak?

You already replaced the BOV?

It sounds like the BOV is venting very slowly in that video you posted, which makes me think it's not getting a good vacuum source from the line.

SSkull

Ended up being a boost leak from the coupler going down from the headunit. Wasn't even visible really, and it seems like it finally gave way when it expanded under boost only. Otherwise it looked completely fine.