Boost Leak?

[VrooomPshhh]

Sorry for the video quality, it was from my phone - anyways, do you guys think I have a boost leak? Look at how the boost just drops to about 8 PSI and I'm currently Stage 1 APR, Neuspeed P-flo and Eurojet DP.

[rawaudi]

Stage 1 should be peaking at 20 - 21 psi. Looks like you are topping out at 15?

[Tutti57]

I am currently experiencing the same issue and am working with my tuner to resolve it.

Have you run any logs with vcds yet?

[VrooomPshhh]

It does peak at 21, depending on which gear I'm in. My thing is, how much boost I lose yet I don't feel much power loss. I understand I will lose boost (hold around 16-18psi) but it goes down to 8psi...I have ran logs but it all seems fine. Maybe it's the boost gauge? I don't know, I just got flashed to Stage 2 and the car is running flawlessly. Next up is BSH PCV valve fix and Forge DV even though I already have the Revision D. Hopefully I'll hold more boost once these are installed.

[bryangb]

You will not be spiking above 20 at stage 1.

You should be spiking around 17-18 and holding 15-16 or so. Which it looks like you are. Boost trails off as rpm's climb. The ko3 runs out of breath at high rpm's. I didn't notice anything out of the ordinary.

[VrooomPshhh]

Did a quick test of the PCV valve and it's going bad, getting the BSH fix will help me hold the boost instead of it dropping down to 8psi like it did in the video. Car pulls like a champ though!

[Tutti57]

Out of curiosity, how did you test your pcv?

[VrooomPshhh]

With the engine on, remove the oil cap - If it creates a vacuum (hard to pull the oil cap off then your PCV valve is bad)

PCV stands for Positive crankcase venitilation. There is pressure in the crankcase if you open the cap you now have created the path of least resistance and you will get pressure coming out of the 1.5" hole vs the .5" hole that is the PCV.

With a PCV system like ours routed back to the intake the point is that whether the vacuum the turbo creates at part and wot or the vacuum is created by the intake manifold at idle it will see vacuum however not too much vacuum. Having too much vacuum will actually literally suck oil right out of the crankcase which is actually more common then the other way with boost blowing into the crankcase.

If you look at that round flat part of the front PCV portion that is a restrictor, at WOT the path to it is closed by a check valve near the connection for the hose going to the intake manifold this prevents boost from blowing into the crankcase defeating the purpose of the PCV.

The opposite though when the car is at idle or under vacuum in the intake manifold at part throttle the rubber diaphram in the restrictor pulls itself more and more closed. The higher the vacuum the less flow. So if you have the car running and attempt to open the cap but cannot due to the strenght of the vacuum or the car stalls out because having the cap open is drawing in that much unmetered air then you know that restrictor failed, quite common for the rubber to tear.

Now if you have so much pressure that the cap blows off or is blowing oil out then you probably have the failed part of the valve that is supposed to seal shut with boost. Oddly this seal works better with more boost (like a DV) and isn't usually increased boost that kills it. STock your car can make 20+psi but is requesting 12 so if it has a leak of say 2psi it can make 14-15 to make the boost it wants, people just don't notice that it fails until their software that is supposed to make 20psi only makes 15 because the leak is greater then what the car can compensate for"

[Tutti57]

Great explanation. Thanks.

[VrooomPshhh]