AZCobaltss

I need some help diagnosing an issue I have been having recently with my ss/tc. The issue is when im cruising, mostly at highway speeds. But any time im in 0 to -10 vacuum my bpv sounds like its releasing pressure. While its happening it will release pressure then grab and build then release repeatedly until im either above 0 and boosting or under 10 vacuum. it makes my highway commute very annoying. So far I want to change the bpv spring but I cannot find where to buy one. I have looked everywhere. im also suspecting maybe a small vacuum leak? or even boost leak? idk guys, help would be much appreciated.

ECaulk

iTrader: (6)

Its not an issue, its how the car is. You either need to demand more throttle (hold boost) or stay out of it (shift to vacuum). Did you recently get tuned?

AZCobaltss

The car has been tuned since I have owned it. it didn't do this before. So I have a feeling its a new problem. Even in 5th gear it does this on the highway. The issue is you can actually feel the car begin to build boost and then lose the pressure to vacuum with no throttle changes. I will post a video. I do not believe this is normal...

Edit: It seems to be most prevalent while at about -4 to -5 vacuum while accelerating, cruising whatever, just most commonly on the highway. It seems like it just doesn't know what to do. So it goes back and forth. I would assume it would either hold boost or keep the valve open, not go back and forth between the two with no changes to throttle or load on the car.

ECaulk

iTrader: (6)

Without hptuners you can't say the load or throttle doesnt change. Do you have a stock bpv or a forge?

Mine does the start to build boost drop pressure, start to build boost drop pressure depending on the weather and if i'm going up a hill, only solution i found was to adjust the tune so the wastegate doesnt start closing so soon at those loads

AZCobaltss

this is true. I have monitored load via wifi obd. and I cannot remember since it was a while ago but I do remember actually seeing a drop in pressure when it did this. I guess I shall see if I get tuned if it will help.

Shanedude

Bpv problems=check your bpv.

ECaulk

iTrader: (6)

What he described was not always a problem. Again lacking all the information makes it difficult to determine if there even is a problem.

AZCobaltss

I'm sorry I'm trying to give you the best information. What do I need to tell you guys?

AZCobaltss

http://youtu.be/CAHAm5yIhV4 here's a video. Hard to hear but you get the idea. My pedal position was the same most the time

ECaulk

iTrader: (6)

So from that video it sounds like the bpv is staying open to long, its not a short let out of air? It sounds like its extended. Do you have the stock bpv or the forge unit?

AZCobaltss

Stock bypass. I can hear it being open and letting out pressure constantly while in vacuum but the the sputter thing happens

Sl0wbaltSS

Plug that bypass valve directly into the intake manifold. Look up the vaccum tank delete mod.
If You've already done it, that's the way the vaccum tank delete works.

blueLNFftw

iTrader: (16)

^^^^
This guy is right.

If doing this fixes how the BPV works, replace the BPV solenoid that it is hooked up to stock (or delete it).
If it does not fix it then you know the BPV itself is bad. Probably a torn diaphragm.

AZCobaltss

I already did the vac tank delete and actually it was fine at first and then started doing this. I'm also getting constant Bpv flutter when I let off now when it used to be every so often . There's something going on just can't figure it out.

blueLNFftw

iTrader: (16)

Reread the two posts above yours

AZCobaltss

Is he saying that's normal or not? I'm confused at the wording.

Sl0wbaltSS

It's normal for it to do that. Do you have the bypass valve into the intake manifold and the other 2 vac lines from the little solenoid plugged into each other? I run it like that.

I can make a vid on how mine works if you want me to.
In the video were you in cruise control or just foot on the pedal?

AZCobaltss

foot on the pedal but it does it in cruise as well. same issue and easy to replicate. if you could post some pics to make sure I have mine setup correctly i only have one hose plugged. i couldn't understand the diagrams that were posted on here but i had thought i figured it out.

Sl0wbaltSS

Here's my setup.

AZCobaltss

cool thanks. mine is a bit different so ill try that. if that doesn't fix the issue I think im going to have to find someone with hpt tuners to datalog for me and then see if my wastegate is staying open too long or what not. and hopfully get a whole new tune as well.

GoodSpeed150

Any updates on this? I'm having the exact same problem.