Hello

Target
I want to adapt the software 8D0907551K from my RS4 B5 to the new base charge pressure (waste gate cracking pressure) of the new turbochargers. The original waste gate cracking pressure is approximately 400 mBar (6 PSI) and now it is approximately 900 mBar (14 PSI).



Possible solutions
I have read in the forum about four different solutions to made this adjustment. As far as I understand, only the following two solutions are possible in my case:



Solution no.1
Only adjust the vpssplg axis of KFVPDKSD and KFVPDKSE maps.

The KFPLGUB and KFDPLGU maps do not exist in the DAMOS of 8D0907551K. This means that I cannot directly modify the calculation of plgrus_w. However, I know the calculation for vpssplg:

vpssplg (Druckverhaltnis Saugrohrsolldruck zu Grundladedruck) = pssol_w (Sollsaugrohrdruck) / plgrus_w (Grundladedruck Sollwert).

According to
, the axis vpssplg has the value 1 for the base charge pressure. I assume that the original base charge pressure has the value 1400mBar.
If I use the assumed original value of 1400mBar for plgrus_w in the calculation and use the new base charge pressure of 1900mBar for pssol_w, I get the following ratio value: 1900mBar / 1400mBar = 1.357142857142857.

The ratio of plgrus_w = 1.357142857142857 therefore corresponds to the new base charge pressure of 1900 mbar.

The values of the axis vpssplg_w of the maps KFVPDKSD and KFVPDKSE multiplied by the factor 1.357142857142857 results in:




In comparison, the original values:



Solution no.2
Only change the KFVPLGU map according to

OEM values:


Values adapted to the new waste gate cracking pressure:




Question to the forum
Do you recommend solution no.1 or no.2 for me? Or is there another solution variant that is better and I'm able to do (please be aware, I'm haven't the skill to change assembler code)?

Thank you PRJ. I really appreciate your advice.


Yes, I have read your posts.
But I don't have the knowledge to change assembler code.


OK, I'll try solution number 2.

How should I calculate the Z-values for KFVPLGU of rows 600-970:

Should I use the delta of the values of the pssol_w axis? Like the following example:


Or should I adjust the Z-values in a way that I get the same shape as stock but increased for my new waste gate cracking pressure? Like the following example:

To be sure that I understand you correctly, I'll ask you with specific calculation steps:

To calculate the values for 600-970 hPa at 3500 rpm, I proceed as follows:
I use the original value at 3500 rpm and 1010 hPa. So the value is 1540.4688 mBar:


Now I calculate the pressure ratio by using my new base boost, in my case 1770 mBar at 1010 hPa and 3500 rpm.




This results in a pressure ratio of 1770 / 1540.4688 = 1.14900088.

Now I calculate all values for 600-970 hPa at 3500 rpm by multiplying the original values with the pressure ratio. The result:

921.0938 * 1.14900088 = 1058.3376
1074.5703 * 1.14900088 = 1234.6822
1151.3281 * 1.14900088 = 1322.877
1228.0859 * 1.14900088 = 1411.0718
1304.8438 * 1.14900088 = 1499.2667
1381.6016 * 1.14900088 = 1587.4614
1484.0625 * 1.14900088 = 1705.1891



If I want to calculate the values at 1750 rpm, I calculate the pressure ratio again. In my case 1150 / 1293.0469 = 0.8893722

Now I calculate all values for 600-970 hPa at 1750 rpm by multiplying the original values with the pressure ratio. The result:

921.0938 * 0.8893722 = 693.88403
1074.5703 * 0.8893722 = 805.4725
1151.3281 * 0.8893722 = 861.23196
1228.0859 * 0.8893722 = 917.02619
1304.8438 * 0.8893722 = 972.82033
1381.6016 * 0.8893722 = 1026.3911
1484.0625 * 0.8893722 = 1102.8216



And so on and so forth. Is that correct?

Hi PRJ

There is no hurry. I would be happy if you could check my calculation method as soon as you have time. I would like to know whether I have understood the basics correctly.