# Peak boost pressure (Audi S3 Stock)



## S3Power (Feb 7, 2013)

Hello people!

I have Audi S3 BHZ (year 2007) ECU 115H.

Someone has logged the turbo pressure (channel 115 vag com) BHZ an Audi S3?

This is normal pressure spike that makes the turbo??? (1'45b). (STOCK)











Channel 002 or 003 of the MAF shows between 3600 rpm and 4700 rpm and a drop because of the pressure peak...











Is this normal? happens in all 2007 Audi S3 BHZ?


Finally someone can add a log of your Audi S3 channels 002, 115?

Regards.


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## S3Power (Feb 7, 2013)

Nobody?


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## GolfRS (Feb 4, 2006)

Normal.

Don't worry about it.


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## S3Power (Feb 7, 2013)

GolfRS said:


> Normal.
> 
> Don't worry about it.


Hello GolfRS and thanks you.

Your car also has the pressure spike?

I realize doing a log to another Audi S3 (motor CDLA) stock that does not have that pressure spike (this car is stock).

AUDI S3 2009 (code CDLA) stock:

Boost:1'2b



Maf: 218 g/s.



And my car Audi S3 year 2007 (BHZ) in same conditions:

Boost= 1'45b.



Maf= 215 g/s.







Observe the difference in the maf (003 vag com) charts and turbo (115 vagcom).



Because my car has that 1'45b peak pressure, and yet this is not another S3 peak pressure and maintains all the while 1'2b?

Regards.


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## GolfRS (Feb 4, 2006)

You are not mentioning if your car is stock or not, but anyways in general in "small" turbos
like the K04 that spool relatively fast the ECU/N75 has a certain reaction lag which means you
may experience a perfectly normal boost spike until the WG is opened to equalize the
pressure.

This "phenomenon" is exacerbated once you start freeing up the engine (intake,exhaust etc)
and is not an issue you should worry about.It will start becoming a problem once you
start requesting higher boost pressures (though software or EBC) in which case it should be compensated
with through adjustment of WG regulation.

Once again, forget about it.....


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## S3Power (Feb 7, 2013)

GolfRS said:


> You are not mentioning if your car is stock or not, but anyways in general in "small" turbos
> like the K04 that spool relatively fast the ECU/N75 has a certain reaction lag which means you
> may experience a perfectly normal boost spike until the WG is opened to equalize the
> pressure.
> ...


Hello GolfRS.

"The problem" is that while the car stock (software) that peak did, and now I've reprogrammed (Stage 1 Revo) continues to make the same peak pressure but 1'75b.

Stock intake, stock exhaust, etc..


Now remap with revo (Stage 1) and I feel the same (peak pressure 1'7b).




Because both the N75 takes the pressure to adjust in my car, and yet in the car of my friend not? Both series cars... :screwy:

Another "problem" (I think it is because of peak boost so exaggerated) is that at the time that the turbo gives the peak pressure (1'75b) fuel pressure drops ...

Being a Stage 1 should not improved pump mounting ... I think my car was slow to adjust pressure and passed blowing.




Regards and very thanks to you!


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## GolfRS (Feb 4, 2006)

There are many reasons for the boost exceeding spec at peak boost, none of them is a real issue
as long as you are simply hitting 1.75 bar.Just enjoy the increased torque and don't worry about it.

As for the fuel drop, you are experiencing a fuel cut just like you said, which normally
shouldn't be an issue with stage 1 programming but from my experience many cars have it,
without something being faulty.It could be that your WG was set a bit tight from the factory (it happens)
or that your fuel pump is beginning to malfunction.Whatever the case there are two things you can do to
"fix" this, one is to lower boost with the sps or check the WG and readjust, OR you can get an
aftermarket fuel pump and have it also ready for when you go stage 2...

Once again nothing to worry about, it's just a mismatch between your requested boost and
the fuel requirements of the TFSI system and turbo....


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## S3Power (Feb 7, 2013)

GolfRS said:


> There are many reasons for the boost exceeding spec at peak boost, none of them is a real issue
> as long as you are simply hitting 1.75 bar.Just enjoy the increased torque and don't worry about it.
> 
> As for the fuel drop, you are experiencing a fuel cut just like you said, which normally
> ...


Thanks very much GolfRS!

Because you think my friend's S3 (engine code CDLA) in 2009 to better manage peak pressure?
The car of my friend not to exceed 1'2b my car reaches 1'45b (stock).
It is possible that the WG S3 tared Restiling have different?

It is possible that the WG S3 tared Restiling have different?

Regards! And thanks for answers.


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## GolfRS (Feb 4, 2006)

S3Power said:


> Thanks very much GolfRS!
> 
> Because you think my friend's S3 (engine code CDLA) in 2009 to better manage peak pressure?
> The car of my friend not to exceed 1'2b my car reaches 1'45b (stock).
> ...


Yes it is possible, and it is also possible you have different version software
because of different ECU part.ANYTHING is possible...

As i said forget about it.


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## S3Power (Feb 7, 2013)

GolfRS said:


> Yes it is possible, and it is also possible you have different version software
> because of different ECU part.ANYTHING is possible...
> 
> As i said forget about it.


You're right, mi ECU is 115H and my friend's ECU are 115AB.

It shows that you understand enough of these engines!

A greeting and thank you very much for everything!


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## cyril_116 (May 31, 2013)

*problem flat spot*

Hi guys,

I have an audi s3 8p with revo stage 2.
I have noticed a flat spot when driving WOT when I change gear.
After a few logs, I have noticed that he peak boost is 2700 mBar (350 mBar over boost specified), and therefore the throttle plate closes up to 50 %.
All the others sensors are ok (MAF,Lambda,advance), only the rail pressure drops a bit, but it s normal as I am still running standard HPFP, and the pressure only drops to 105 Bars, vs 130 Bars requested.
The N75 seems to regulate the pressure and opens to 51 on peak pressure, but i am wondering if there is any strategy forcing the throttle plate to closed when the peak pressure is too high and the N75 is struggling to regulate the pressure, or is there something else i need to look for.

Thanks

I wanted to post a picture of the log but the forum only alloows me to attach a picure via URL and not to browse through my computer (sorry new to this forum


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