N55 E92 on Pure 750 / Load & Boost Request Issue

valpfrmnc

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Nov 11, 2023
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Hello Guys,
Its my first post here and my first topic. Usually i just quietly read and havent contributed that much because i just recently started to tune on my own. Currently working on a E92 N55 BMW with the MEVD17.2 ECU. Engine is built and with a big turbo (Pure 750) and all supporting mods so it can easily support over 2 Bar/30 psi relative boost pressure. Car is running on E40-E50 to avoid timing correction on stock timing maps. For some reason the car never requests over 180% load or 2.2 bar absolute pressure. All load ceilings and torque ceilings are raised, pressure limiters raised and i cant find the limiting variable. I would be very grateful if someone can shoot me in the right direction.

N55 Pure 750 E90 Log
 

wheela

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Jun 4, 2021
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Can you post up the specific tables you've increased, or rescaled break points to higher load and/or MAF?
 

valpfrmnc

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I attached the stock and tuned file. I am running mafless btw.
 

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  • BMW 335i 2011 Val Pure 750.bin
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houtan

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Nov 2, 2017
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you are targeting 230 in your load ceiling main table. but your load to torque y axis max is 220. If you want to reach 230, you would need to adjust the max value in the y axis to at least 230 to theoretical achieve that load request.

looks like you are trying to tune via PID and my guess is your issue is there. but I defer to someone else as that as i use an EBC. @JPuehl or @Stokes may be able to help.

are you running PI? what controller?
 
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Stokes

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Jan 26, 2018
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I attached the stock and tuned file. I am running mafless btw.
The only thing I see odd is your values in the Maximum Torque Characteristic table. Try setting them to 3276.7 (off) and see how it responds. But usually when you hit a ceiling there it pulls timing. So, probably not the issue.
1699887939979.png

1699887577372.png


You're next limiter will be setpoint. It's near 2.4 already with a 2.7 cap. But, change one thing at a time.

Curious why you changed these... is that how you are taking MAF out of the equation?
1699887735164.png


The log looks like it's torque based control and not load, which I've not seen on the N55. Most likely something is set that is limiting load request.
 
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valpfrmnc

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Nov 11, 2023
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Thank you Guys, appreciate your time!
@houtan , yes i will be tuning via PID and not using commanded wastegate. Just by my experience from other ECUs you dont have to rescale those tables. That would mean i would be flatlining but my load request is even tapering off in the high RPM so there must be another limiter.
@Stokes I set the cap cause my fuelling isnt 100% dialed in on the PI side as i am only using base maps so dont want to overshoot with my targets and cause issues running lean or something. Controller is a Motiv Reflex+. The values for the pressure sensor are just basic 3.5 Bar MAP sensor calibrations.
 
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Stokes

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Jan 26, 2018
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Disclaimer: I'm an amateur tuner.

Ah, makes sense for the Tmap sensor. I still use the MHD option during flash.

You have a lot of changes that aren't in my XDF. I found another XDF to see some of those other changes and found your Desired Torque table changed. I have no idea how a value over 100 will be used, but as for testing, you could revert this table back to factory and see. I'm only suggesting this because I found the system does weird things if you go above a ceiling value.

1699895580658.png


F-n55 values are more linear.
1699895604700.png


X5M/S63tu has the above table 0ed out and uses this one, with seemingly more aggressive values.
1699895782003.png
 
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valpfrmnc

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Nov 11, 2023
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I am not an amateur tuner actually but for the BMW world i am :D. Thats why you also see a bit more changes since i am using WinOLS with a full DAMOS to do my tunes. I changed the requested torque just to cap any request limits so multiplying the desired torque by a higher value. Technically wouldnt make a change to be fair since your indexed torque is 1000 nm and if i request 100% or 150% of the maximum indexed torque it makes 0 difference. I dont use MHD to flash it since the E Series N55 doesnt benefit of MHD at all.

If i will figure this out i will keep the forum posted, i guess i am the first one with a Pure750 on a N55 E Series. Might be a good input for others looking to get a big hybrid on their E series.
 
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Stokes

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Jan 26, 2018
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One last thing I noticed was a use of a table that seems only used for torque managed tuning... K_RF_MAX in my XDF (0x1819A0 location). Are you setting values in the maximum relative filling characteristics tables? I've been trying to figure out how BMW sets up these DMEs for load vs torque managed. The X5M uses a simliar DME (two of them actually) and is based on torque. So when I see values changed for tables used for torque managed, I wonder if you accidentally are not load based anymore.

I'm on the Pure 750 (early adopter). I'm severely limited on power until we sort out the 65536 tq limit > 5500 rpm once it starts making power. I still have the S55 flywheel ready to go in, but it seems the next limit issue is at 600hp.
 
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Stokes

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Jan 26, 2018
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2011 BMW 135i
I am not an amateur tuner actually but for the BMW world i am :D. Thats why you also see a bit more changes since i am using WinOLS with a full DAMOS to do my tunes. I changed the requested torque just to cap any request limits so multiplying the desired torque by a higher value. Technically wouldnt make a change to be fair since your indexed torque is 1000 nm and if i request 100% or 150% of the maximum indexed torque it makes 0 difference. I dont use MHD to flash it since the E Series N55 doesnt benefit of MHD at all.

If i will figure this out i will keep the forum posted, i guess i am the first one with a Pure750 on a N55 E Series. Might be a good input for others looking to get a big hybrid on their E series.
Haha, we fully agree on the MHD comment. Logging is very nice though through the app.

If you want, I could set up a bin that should work without a lot of the changes you've done. If it work, you can back out your other changes until you find the one causing the issue.
 
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wheela

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Thanks for all this awesome sharing you guys! I'll be attempting to self tune my speedtech kit in the near future, so I'm sure I'll be encountering similar challenges. In the meantime I'm just trying to soak up as much as I can, and help others out whenever I canđź‘Ť
 
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houtan

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Nov 2, 2017
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I am not an amateur tuner actually but for the BMW world i am :D. Thats why you also see a bit more changes since i am using WinOLS with a full DAMOS to do my tunes. I changed the requested torque just to cap any request limits so multiplying the desired torque by a higher value. Technically wouldnt make a change to be fair since your indexed torque is 1000 nm and if i request 100% or 150% of the maximum indexed torque it makes 0 difference. I dont use MHD to flash it since the E Series N55 doesnt benefit of MHD at all.

If i will figure this out i will keep the forum posted, i guess i am the first one with a Pure750 on a N55 E Series. Might be a good input for others looking to get a big hybrid on their E series.
Awww man. You said the magic words, WinOLS. Hahaha.

There are a few ps750s running around on e series cars. The ones that are reaching 600whp are running into a similar issue like me. We get a cylinder 4, 5, or 6 misfire code at a similar rpm (5,900), even though the log is clean.

In the n54 forum, a similar issue was posted and resolved by disabling misfire detection above a certain rpm using this table, WIP - Testing > Misfire Detection Max RPM (AT/MT). We can’t find that table in our xdf, but we were pointed to a table called CDMD, which is misfire detection, and it can be turned completely off. I tried it today and it seems to have worked, but I would much prefer to only disable misfire detection where necessary, which is around 5,900 rpm.

Are you able to find a table similar to WIP - Testing > Misfire Detection Max RPM (AT/MT)?
 
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valpfrmnc

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Yes there is a MAP where you can disable that based on Gear and RPM. Address in my Bin is 1C336A, 11x1. Z Data Factor is 0.25
There are way more tables to adjust that. The best way is to do that no by disabling the entire system but adjusting the Filters and Sensivity as you loose your DME Control over misfire and safety. Once i will figure out my load issue and get the car dialed in i can share some insights. Goal for this built is 750 WHP on full E85.
 

houtan

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Nov 2, 2017
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135i N55 DCT; PS2
Thanks. I think everyone totally agrees, We don’t want to disable it completely. This issue has been around for a couple of years for me, with no solution in sight. But you give me hope!

We did play with reducing sensitivity in the second bank of cylinders as well as sensitivity for cylinders 4, 5, and 6. No luck.

Today I did a second test run to verify the table that completely disabled misfire detection is working properly. And it does! I was finally able to run more than 600 wheel and clicked off one of my fastest 100 to 200 km times to verify. But I would much rather implement the approach you explain.
 

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valpfrmnc

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@Stokes If you have some time you can shoot me a bin that i can try. Maybe i am just overcomplicating things on this ECU. Thanks for your help!
 

JPuehl

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Jul 24, 2019
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Yes there is a MAP where you can disable that based on Gear and RPM. Address in my Bin is 1C336A, 11x1. Z Data Factor is 0.25
There are way more tables to adjust that. The best way is to do that no by disabling the entire system but adjusting the Filters and Sensivity as you loose your DME Control over misfire and safety. Once i will figure out my load issue and get the car dialed in i can share some insights. Goal for this built is 750 WHP on full E85.
I was able to find the table you refer to and make a table def for the XDF, but most of the other "by gear" tables are 0-9 (so 10 columns), do you know the order of the columns to gear? I.E. is column 1 basically neutral but labeled 0, then column 2 gear/labeled 1? Thanks for the responses.
 
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valpfrmnc

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BTW, how did you solve the intake? Can you show me your engine bay?
Nice build for sure! 135i will always be superior to the 335i cause of the brakes and overall platform advantages.
 

Stokes

Sergeant
Jan 26, 2018
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Houston, TX
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2011 BMW 135i
@Stokes If you have some time you can shoot me a bin that i can try. Maybe i am just overcomplicating things on this ECU. Thanks for your help!
Here's one. I wasn't able to get out and test it to make sure I had all the minimum tables covered, but I'm 89% confident I have them. LOL. Copy in any fuel/ignition safeties, otherwise it's your stock plus min tables to increase load request. I softened D-factor some to keep it from oscillating on you. Rest of the tables are stock, so this is only to verify you can reach a higher load target (aka wgdc model and compressor characteristic tables are factory wack).

EDIT: This file doesn't have the settings for a 3.5 TMAP.
 

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  • BMW 335i 2011 Val Pure 750 TEST1.bin
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