2014 S5 - Won't boost much beyond OEM levels with GIAC Stage 1

[speedyf16]

I'm hoping somebody has run into this issue before.


As you can see in the data logging snap shot I've attached, with the bypass valve completely closed there seems to be boost bleeding/leaking SOMEWHERE else because it isn't coming close to boost levels as seen in pretty much everybody else's 3.0T GIAC Stage 1 re-flash.


The guys at GIAC are saying I should be seeing at least 12psi with this tune (similar to what guys in Denver at high altitude get - but I'm just at 3500 feet) and I'm only getting 8.8psi with the BPV closed. I'd like to think that my brand new car that runs a very strong 13.1 @ 105mph on the stock OEM tune doesn't have a boost leak. Maybe the GIAC tune is requesting the BPV to be 100% closed but even though it's reporting closed maybe it really isn't.


But if I really do have a boost leak (I suppose it's possible the leak only shows up above stock boost levels??) where could I be losing all the boost to?


Any suggestions where to start looking for the boost leak?? Or could the by-pass valve be falsely logging that it's 100% closed (I don't know if it's controlled through vacuum or VDC)?


Any help is much appreciated!


2014 S5, DSG, AWE S-Flo Intake

 

[warren_S5]

Did the car feel down on power pre-remap?

 

[speedyf16]

Nope. Pre-map and on the "stock" setting on the flash it runs awesome. 13.1 @ 105mph - feels as good as a stock S4/S5 should.

Looks like stock boost is around 7-8 on these cars as I've read? And they're saying I'm getting 8.8psi....so still getting stock levels somehow with a leak....seems odd to me. If there's a boost leak, I don't see how it only manages to develop on the tuned setting.

 

[warren_S5]

Odd. I wonder (and I know very little about this engine as I've only owned the car for 8 weeks), when the higher boost is requested whether it's putting the car into a form of limp mode as other parameters can't be met?

Can you get it checked for error codes (locally)?

 

[speedyf16]

That's a really good theory, however there are no codes. We even cleared the entire tune and tried again with the same result. Perhaps there's a parameter not being met that doesn't trigger a code. But we sent all of the data logs in Excel format back to GIAC and they looked at all the parameters being measured and only reported back what I posted as being out of whack.

 

[speedyf16]

I'm still thinking it could be the BPV. I'm a jet turbine Engineer and I've seen many times where bleed valves and blow off valves say they're closed, but when you actually remove them and supply them with correct closure voltage they're not actually fully closed and therefore "leaking". This of course would be a mechanical problem unless the signal being sent by the GIAC tune is not properly communicating with the BPV's control module.

 

[speedyf16]

Ended up going with the APR Stage 2+ - pulley and tune. Max boost is 1974 mbar (13.93 psi with atmosphere). Nothing super huge but today's runs averaged out to about 12.75s @ 110mph at a density altitude of 4142 feet, 0-60 in 4.3 seconds. This is on the 91 Octane tune with 94 Octane fuel. Was hoping for low 12s but perhaps on the 93 tune and closer to sea level I'd be nearer to low 12s.