N55 E92 on Pure 750 / Load & Boost Request Issue

houtan

Lieutenant
Nov 2, 2017
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135i N55 DCT; PS2
And for me, I wouldn’t experience any actual misfires, car would be pulling hard, then bam, misfire code would trigger at high boost. Usually around 600whp.

It would feel like I was hitting some sort of limit, so the airmass table seems to make sense as a possible reason why.

I also had fuel related misfires due to rail pressure dropping back in the day. That’s when PI went in to fix that issue.
 

wheela

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Jun 4, 2021
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2015 e84 X1 35i Msport
And for me, I wouldn’t experience any actual misfires, car would be pulling hard, then bam, misfire code would trigger at high boost. Usually around 600whp.

It would feel like I was hitting some sort of limit, so the airmass table seems to make sense as a possible reason why.

I also had fuel related misfires due to rail pressure dropping back in the day. That’s when PI went in to fix that issue.
That's intersting, if the airmass table is playing a role, I'd expect you'd still feel like you're hitting a wall, except without the misfire code since you turned that off. But you got faster 60-130 times when you turned off misfire detection? Did it still feel like you were up against some kind of artificial limit?
 

houtan

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Nov 2, 2017
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That's intersting, if the airmass table is playing a role, I'd expect you'd still feel like you're hitting a wall, except without the misfire code since you turned that off. But you got faster 60-130 times when you turned off misfire detection? Did it still feel like you were up against some kind of artificial limit?
I never hit a wall before. The car would be pulling hard and then just go into limp mode for no reason. You don’t feel anything abnormal until the limp mode because one of the cylinder gets deactivated. When I say trip
Some sort of limiter, I don’t mean you feel it, but in the sense that I reach some sort of limit and the cel comes on.

With the misfire detection off, it felt exactly the same, except I could actually complete the pull without the dme going into limp mode and deactivating a cylinder.
 

valpfrmnc

Lurker
Nov 11, 2023
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Hey guys,
Quick update. I solved my issues with the low load requests. Load to Torque tables were too low for the boost target i wanted to run and the DME reduces the requested load if you are overboosting. So your tables have to be rescaled high enough to be over the boost target.

Next issue is, when i hit 26+ psi it starts misfiring/backfiring. I have two 450 walbros and PI that kicks in at 18 PSI. Coils are upgraded to B58 ones. My rail pressure drops down to 1300-1400 psi so i am thinking the HPFP might be bad on this car. Any ideas?
 

wheela

Lieutenant
Jun 4, 2021
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Twin Cities, MN
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Hey guys,
Quick update. I solved my issues with the low load requests. Load to Torque tables were too low for the boost target i wanted to run and the DME reduces the requested load if you are overboosting. So your tables have to be rescaled high enough to be over the boost target.

Next issue is, when i hit 26+ psi it starts misfiring/backfiring. I have two 450 walbros and PI that kicks in at 18 PSI. Coils are upgraded to B58 ones. My rail pressure drops down to 1300-1400 psi so i am thinking the HPFP might be bad on this car. Any ideas?
Thanks for following up on your low load request issue!

For DI only, I've read that around 1700 psi is about as low as you can go without mis-firing; n55 doesn't seem to be as tolerant of low rail pressure as n54. I'd aim to keep it above 2000 psi. But you have PI supplementing, so I'm not sure how that affects things. I can't remember, are you still on the stock hpfp?
 
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Stokes

Sergeant
Jan 26, 2018
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Houston, TX
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2011 BMW 135i
Are you positive PI is kicking in? You can increase duty cycle on the hpfp, but you shouldn't have to unless you're consuming all the LPFP has to give.

Log VCV (hpfp duty cycle) and see how much it's asking for. That should tell you if the hpfp is going bad. Stock settings will only request around 60 something percent.
 

valpfrmnc

Lurker
Nov 11, 2023
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PI does kick in as I monitor it live and also visible on the fuel trims. Running MOTIV Reflex+ with E40.
 

JPuehl

Specialist
Jul 24, 2019
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Greater Seattle area (a.k.a. Zombie Land)
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2011 135i 1M clone N55e DCT
PI does kick in as I monitor it live and also visible on the fuel trims. Running MOTIV Reflex+ with E40.
I have a Reflex+ using E50 with my PI. As Houtan mentioned, can you share your Reflex BIN and a log if you have it? Also, are you using the base/OTS MAP/BIN that Motiv has? I started with that, made only a few changes and it was perfect, not many changes were needed.
 

valpfrmnc

Lurker
Nov 11, 2023
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Hey Guys,
Sorry that i didnt update you guys but i had to take care of family and other cars so left this project alone. Just got back to it and sorted the PI issue out. Now when i start building boost its just cuts off and shows traction control and abs errors till i restart the car. Any ideas?
 

valpfrmnc

Lurker
Nov 11, 2023
23
15
0
I would get 36CA or 5E19 in the ABS Module. Seems like something is off with the load target/request or torque monitoring.




Log
 

valpfrmnc

Lurker
Nov 11, 2023
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What i dont understand is that even though i set the commanded wgdc to 50% it still commands more than 70% and even 80% so the boost spikes hard.
 

valpfrmnc

Lurker
Nov 11, 2023
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New log, was able to turn down wgdc but still same issue
Log

How are your guys load to torque tables and the monitoring tables look like?
 

houtan

Lieutenant
Nov 2, 2017
611
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135i N55 DCT; PS2
Can you add tq 1, 2, and 3 channels?

Also, can you attach a copy of your current bin?

Load to torque z values are pretty much stock.
The y axis max value needs to be equal to or greater than the load request you want. So if I have load request at 255, my y axis needs to be at least 255 or greater.
 
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valpfrmnc

Lurker
Nov 11, 2023
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TQ Limiters are not kicking in, all set to 0 in the previous logs i did. Load request is scaled accordingly.
 

valpfrmnc

Lurker
Nov 11, 2023
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Other changes that are not in XDF are just few DTCs off and torque limiter in limp mode raised.
Taking back my statement, in this one load axis is stock cause i wanted to try stock tables but issue is still present, even with low boost target. I am not even overshooting load or boost as you can see in the log.
 

Attachments

  • 335i N55 Val Pure750 - V27_mhdbin.bin
    4 MB · Views: 8
  • stock_mevd172_335i_n55_val_updated_mhd.bin
    4 MB · Views: 5

houtan

Lieutenant
Nov 2, 2017
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135i N55 DCT; PS2
I didn’t see anything super obvious but one of your torque limiters was set outside of the dme range and others were lower than we run so i changed them to match our values. You can compare to your current tune.

What PI controller are you using?
 

Attachments

  • 335i N55 Val Pure750 - V27_mhdbinHM.bin
    4 MB · Views: 17

houtan

Lieutenant
Nov 2, 2017
611
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135i N55 DCT; PS2
@valpfrmnc , post 367 here. Any ideas on what is causing the issue?

 
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