What happens when your BOV leaks?

[DaveDSM]

or opens too soon?

I get up to 4k under boost and the car will make a rev limiter-like sound before boost falls off.

 

[midnght]

the car will make a rev limiter-like sound before boost falls off.

That is your answer.

You are leaking boost and causing an improper air/fuel mixture. If you are tuned pretty tight then you will get a bucking feel and a sound just as you described.

 

[DaveDSM]

That is your answer.

You are leaking boost and causing an improper air/fuel mixture. If you are tuned pretty tight then you will get a bucking feel and a sound just as you described.

I've leak tested the car to 18 psi. The BOV leaks around 8 psi. The Hallman ES starts leaking around 4 psi at the copper barb. I tape that off. My intercooler piping is all sealed down, new gasket on the compressor outlet. I can't find a leak from the TB, valvecover, or fuel injectors. I've even replaced the leaking oil cap. At idle before driving, the vac gauge will read 22 hg in, then go up to 20hg in. After a long drive it can go as high as 14 hg in, but spends a majority of its time around 16-17hg in.

Where else can I check?

Thank you,
Dave

 

[midnght]

At idle before driving, the vac gauge will read 22 hg in, then go up to 20hg in. After a long drive it can go as high as 14 hg in, but spends a majority of its time around 16-17hg in.

Where else can I check?

These are all normal readings. The vacuum will be at different levels dependant on a few things. In gear, out of gear, partial throttle, no throttle.


Do you "hear" something or is it a slight bump in the car when you reach a certian RPM or Boost level?

 

[DaveDSM]

These are all normal readings. The vacuum will be at different levels dependant on a few things. In gear, out of gear, partial throttle, no throttle.


Do you "hear" something or is it a slight bump in the car when you reach a certian RPM or Boost level?

It used to be a bump, but after closing off the leaks I've mentioned, it has now become a noise I hear.

 

[midnght]

Does this noise happen when boost is building or when the car is idle?

 

[DaveDSM]

Does this noise happen when boost is building or when the car is idle?

When boost is building.

 

[midnght]

Maybe it is time to replace the BOV?


My GReddy-S gets a squeal to it when I go partial throttle at around 15psi, but once I punch the throttle it goes away and holds all the way.

 

[DaveDSM]

Maybe it is time to replace the BOV?


My GReddy-S gets a squeal to it when I go partial throttle at around 15psi, but once I punch the throttle it goes away and holds all the way.

Well, it is load-dependent, not psi. In 2nd it will boost 16psi before making that sound, in 5th it can start giving trouble around 8-10psi.

I'm thinking there may be another boost leak somewhere, or maybe the BOV is the root of the entire problem at this point?

Rest of the car has checked out fine on leak testing, except the oil dipstick, which I wil replace..

Timing on the cams should be spot on, and base timing is 5 degrees. I'm trying to think what else would cause vac issues/boost difficulty.

 

[CanadianTSi]

Your not venting are you?

 

[DaveDSM]

Your not venting are you?

Nope.