F1X 000021571DAA01 MHD DIY tune boost deviation question - not calculating correctly above 2.5 bar

[mikesrex]

Right now, the car works perfect up to 22 lb boost on my DIY tune. When I boost over 22 lbs, the boost deviation calculation does not work correctly, and I believe it is due to using a calculation of boost target RAM minus the manifold boost pressure. Manifold boost pressure maxes out at 22.5, I guess due to having a 2.5 bar TMAP.

I notice that my Wedge tune has correct values in the boost deviation log values. I also notice my other car I tuned myself (2017 540i) has correct values for boost deviation, with no special coding or changes to the standard tune.

The issue with having incorrect values for boost deviation with boost target RAM values above 22.5 lbs means that the custom P tables I use increase the WGDC even if the car is boosting ok. This leads to a runaway condition for actual boost, since it keeps adding wgdc when it should not. I can do weird stuff to fix this, but would rather get the logic working correctly.

thank you to anyone who can help. I can pay for advice on what to do, but keep in mind my goal is to finish tuning the car with a tune I can easily edit at the track to get best results.

I would like to get best effort on my Shuenk N55+ turbo, before I upgrade to a bigger turbo. Here is my best run on my N55+ turbo when the car weighs in at 4020 with driver:

 

[mikesrex]

so far I hear that I need to modify the PVDMAX table on my tune, but it is not a table currently in the 000021571daa01.xdf I have that I got from the MHD github. If someone could tell me where it is in the BIN i would greatly appreciate it lol. WIlling to pay for good help

 

[fstbtstr]

You probably mean PVDMX, not "PVDMAX" "Obere Druck Schwelle fuer Range Check" - "Upper pressure threshold for range check". I can take a peak at your ROM, won't be too quick, though. I don't need any payments, would be interesting too help a cool project. That f10 does move.
P.S. turns out I have already been looking at this ROM, I thought this was an M235i ROM? Anyhow, PVDMX should be at 0x1ce63c, 16 bit LoHi value. Multiply your desired threshold in hPA by 12.8 and convert to hex with low byte first. To convert your current val to hPa, multiuply by 0.078125. Seems like 000021571daa01 has "00 82" or 0x8200 as its PVDMX value, which is 2600hPa

 

[mikesrex]

You probably mean PVDMX, not "PVDMAX" "Obere Druck Schwelle fuer Range Check" - "Upper pressure threshold for range check". I can take a peak at your ROM, won't be too quick, though. I don't need any payments, would be interesting too help a cool project. That f10 does move.
P.S. turns out I have already been looking at this ROM, I thought this was an M235i ROM? Anyhow, PVDMX should be at 0x1ce63c, 16 bit LoHi value. Multiply your desired threshold in hPA by 12.8 and convert to hex with low byte first. To convert your current val to hPa, multiuply by 0.078125. Seems like 000021571daa01 has "00 82" or 0x8200 as its PVDMX value, which is 2600hPa

thank you very much, I added this parameter in my XDF and will try it out. My current value is 2600, and will try 3500

 

[fstbtstr]

no problem, let us know how it goes.

 

[mikesrex]

no problem, let us know how it goes.

Worked great! Here a little 1/8 mile hit on asphalt with a soft launch

 

[fstbtstr]

Worked great! Here a little 1/8 mile hit on asphalt with a soft launch

excellent! I'm glad I can find something useful in these DMEs, not just some maps and functions not relevant for tuning. Please keep us posted on further progress, let's see if we can help you further.

 

[wheela]

Damn, you have blistering 0-60 times!!

 

[mikesrex]

Damn, you have blistering 0-60 times!!

Best 0-60 is 2.67 so far. Was at the track and cut a 1.46 60’ that day

 

[mikesrex]

excellent! I'm glad I can find something useful in these DMEs, not just some maps and functions not relevant for tuning. Please keep us posted on further progress, let's see if we can help you further.

Next step is getting my boost dialed in for fastest quarter mile. I have a great launch and believe I’m close to best effort. Current boost settings basically use boost levels that made the most whp in this dyno chart basically targeting 28 lb in mid range and then tapering off to keep the power at max levels with the lowest possible boost. Will get my fuel trims dialed in well first. Then i will vary the boost up and down to see what makes the car accelerate the fastest at every part of the run. Once i find that sweet spot i will play with timing. Hoping for 10.4-5 with the Shuenk N55+ and then it’s time to upgrade to its big brother the Frankenturbo F55. RiP transmission lol