Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby HF1600ie » Fri May 10, 2013 1:34 pm

anyone ?

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby HF1600ie » Tue May 28, 2013 1:30 pm

I swapped my K14 for another K14 and now I only have 1 bar boost more or less stable.
I am requesting 2200mbar (I saw this requested boost in vag-com) just as before. Strange isn´t it ?

So... now boost doesnt drop from 1,2 to 1,0 but it just stays at 1,0. Turbo starts at 1900rpm and kicks harder at 2700rpm now.

Funny thing is that I have adjusted fuel maps a lot down to avoid smoke (I have now more or less from 20:1 to 16.5:1 in AFR table / smoke map).
Also torque limiter is softer bellow 2000rpm.
My current map is basically an OEM "+" version with PP764 with adjusted smoke map and pump tension to get rid of unwanted smoke. Smoke is very very low at the moment. Almost OEM I would say.

So, this may explain that my previous drop from 1,2 bar to 1,0 was nothing more than a boost peak because fuel delivery was stronger and there were more exhaust gas going into turbo.

But it does not explain why vag-com shows requested boost of 1,2 bar (just like in my tune) and only delivers 1,0 bar!!!
Maybe vag-com readings (factor) are wrong for this ECU ? :crazy:

Should I request 1,4 bar to have 1,2 bar (actual boost) ? :lol: :lol:

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby zok » Tue May 28, 2013 4:29 pm

Stock setup (in your uploaded file) is 0,85 mbar relative, right?

The map you posted looks like a N75 map to me.

I attached 3 pics for example: N75 map of TDI and dCi (both VGT, but TDI is vertically inverted according to dCi), and another wastegated dCi (my laguna - screenshot of winols).
You do not have permissions to view the files yet. You have to be registered and you have to make at least 3 quality / unique posts.

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby HF1600ie » Tue May 28, 2013 6:58 pm

Hi,
Yes, OEM file is about 0,85 bar boost.

That map looks like N75 in shape. It is very very close to the shape of the N75 map in EDC15 from Audi A4 110hp TDI (AFN engine) and many others from those years.

However, I have no factor for axis and when I select axis from hexdump the values that show up make no sense to me... :crazy:

Assuming that it is N75 related, do you think I should tweak it to mantain boost or to raise it to desired value ?
In my previous car, Audi TDi 110hp I never needed to touch this map to achieve 1,2 or 1,3 bar. Turbo was VNT15...not K14.

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby zok » Tue May 28, 2013 9:46 pm

damn, I wrote a very long reply, but accidently closed the tab in mozilla. :eh:

You can do a test: attach a probe lamp to your N75 valve, and try 3 different settings in this map where idling should be (the higest part of the map): 0, 50 and 100%: at 0%, the light should be off, change the map to 50%, the light should blink pretty fast (50% of time on, 50% off) or even glow slightly if the PWM frequency is too high, and at 100% it should light up at full power. Or it could be the opposite way: on at 0 and off at 100%.

If you own an oscilloscope, then you should try with it (and then you know exactly what I mean), and if it is a digital one with a memory function, then everything is even easier. :)

I think your bih has 0 for 0% and 255 for 100%.

But be careful - EDC15 for VAG VGT turbines has opposite data for N75 valve than EDC15 for renault, and because we don't know how is at your case, the best way to find out is to make the whole map 255 for the first try, 127 for the second and 0 for the third shot. That way, you can find out what is what, and even find out which axis is RPM, which is IQ and what is the duty cycle logic. :thumbup:

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby HF1600ie » Wed May 29, 2013 3:05 pm

That´s an interesting test i will try to perform. I think I have a probe lamp.
In my ECU, and if that map is really N75, then binary 255 should be wastegate 100% closed. And binary 0 should be wastegate 100% open. This is the same in VNT15 vag EDC15. However, If I select the axis, the values are either positive or negative, which doesn´t make much sense. It should be "IQ" vs "RPM" for X and Y axis and in Z axis we would have "%"

I also find it strange that I need to tweak this map to get 1,2 bar boost. Well... maybe I have to close wastegate a little more to achieve it.

At the same time, I don´t find SVBL anywhere. Although I have hear it is = "1990" in 16-bit mode HI-LO and I can find two values "1990" in Eprom, although ECU is 8-bit.
But if this was true... then vag-com log could never show a requested value of 2180mbar which is 1,2 bar boost.

It means SVBL > 1,2 bar.

Am I pointing in the right direction ? What in the world is needed to rise boost in this ECU ?!

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby pechenikov » Mon Dec 23, 2013 6:37 pm

MAP sensor can not account for more than 2000mbar

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby slowianin » Wed Dec 25, 2013 6:00 am

what I have to do to see the links?

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Re: Audi A6 2.5 TDi - 115hp AAT - Boost doesn´t hold

Postby HF1600ie » Mon Jan 13, 2014 4:12 pm

Could well be the problem.
But in my "AAT" engine, the MAP sensor is able to go up to 2500mbar. Older 2.5TDi than mine had 2000mbar limitation, but not mine.


pechenikov wrote:MAP sensor can not account for more than 2000mbar

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