N54 Log and Fighting with Target Boost.

Sava666

Specialist
Dec 14, 2020
75
11
0
Hi folks. Quick Self-Tuning Questions. Can't bother my "tuner", because he's pretty busy nowadays again. So I'm doing it myself AGAIN. Can somebody assist? N20TMAP installed, tables adjusted (Did my best, maybe couple of them left untouched).

1) Can someone explain what's going on with the Boost Target (see pic)? Why is it so sunken (concaving) in the beginning? Maybe it has something to do with scalars? I know I can adjust with BRO or BPTM, but it's not helping much, and concave still remains. Even drawing down BRO up to 85. So I'm lost right now.

2) Who can explain why Load Actual values are always so close to the Load Target values (Frequently getting Throttle Closures because of sunken Target just in that area of beginning), even if I set the Load Limit Factor to 90% out of 100%? BLM is 3.5 out of 4. What is keeping it close to the Load Target?

3) Not bad WGDC B1/2 with dead stock tornado-machines, is it? Still have plenty room for fun with inlets on place. 24psi on 2-3 degrees dropping to 18psi-ish in the end is my goal.
PS. I know about fuel pump. That's not a reason at all.
Almost satisfied, but still willing to know "the answers".

4) Who can advise on WGDC sunk in the beginning? I'm tired of PID tuning. Can't get it right in that place.

Issue attached below!
Logs attached: https://datazap.me/u/savarenova/winter-wgmin10?log=1&data=5-6-7-22-25

@RSL @chrisdfv @V8bait @carabuser
 

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carabuser

Lieutenant
Oct 2, 2019
548
1
410
0
UK
Ride
Z4 35i & 335i
Nothing to do with scalars, PID or load target. It's a proportional reduction applied during the boost target calculation beneath 4k RPM. The table to fix this isn't in the public XDF and probably won't be added.

There isn't a simple conversion factor to convert load into a boost target, it's much more complicated than that and with good reason. The reason the "modern" BMW turbos engines drive like NA engines rather old school turbo motors is because of the huge amount of code BMW created to control the manifold pressure target.

The issue is that when tuners make changes to the stock map they change the wrong tables or only change some of the tables in that mass of logic in an attempt to raise the target manifold pressure. Like you mentioned you have been messing with the BRO table and putting a high figure in the BLM table which. It works in a limited fashion for most tuners but cracks start to emerge when you look closely. What you are seeing is the result of a poor tune which is exasperated by the fudging of the TMAP sensor scaling.

If you just want a dirty way to get a nice high boost target at any RPM then you can just set your boost ceiling up to where you want the max boost to be, raise the BLM and Load Limit Factor then set yourself a really high load target. The output of the boost target calc is maxed out at 23PSIg with MBoost enabled so if you target 300 load then you'll be maxing out the raw boost target by about 7PSI so the low RPM reduction will irrelevant. The raw boost target should then just be pegged at 23PSI (or lower depending on what you set the boost ceiling at), your TMAP sensor scaling will then take effect and bring it up.

Probably won't drive nice but it'll get you what you want.
 

Sava666

Specialist
Dec 14, 2020
75
11
0
Nothing to do with scalars, PID or load target. It's a proportional reduction applied during the boost target calculation beneath 4k RPM. The table to fix this isn't in the public XDF and probably won't be added.

There isn't a simple conversion factor to convert load into a boost target, it's much more complicated than that and with good reason. The reason the "modern" BMW turbos engines drive like NA engines rather old school turbo motors is because of the huge amount of code BMW created to control the manifold pressure target.

The issue is that when tuners make changes to the stock map they change the wrong tables or only change some of the tables in that mass of logic in an attempt to raise the target manifold pressure. Like you mentioned you have been messing with the BRO table and putting a high figure in the BLM table which. It works in a limited fashion for most tuners but cracks start to emerge when you look closely. What you are seeing is the result of a poor tune which is exasperated by the fudging of the TMAP sensor scaling.

If you just want a dirty way to get a nice high boost target at any RPM then you can just set your boost ceiling up to where you want the max boost to be, raise the BLM and Load Limit Factor then set yourself a really high load target. The output of the boost target calc is maxed out at 23PSIg with MBoost enabled so if you target 300 load then you'll be maxing out the raw boost target by about 7PSI so the low RPM reduction will irrelevant. The raw boost target should then just be pegged at 23PSI (or lower depending on what you set the boost ceiling at), your TMAP sensor scaling will then take effect and bring it up.

Probably won't drive nice but it'll get you what you want.
@carabuser I didn't know that Boost Ceiling changes too once you rescale into 3 cell. I thought that it's a raw boost limiter. Can you approve/reject this message? Is there any specific 3 cell related rescale calculation for boost ceiling?

Do I copy you correctly? This means to raise load target high enough so load actual won't be physically able to reach it, and control (pegg) it by boost ceiling considering 3 cell scaling application?
1) Set boost 1.28 (should work for 24 psi)
2) Raise BLM (Is BLM ceiling 3 OK?)
3) There are not much info on what is Load limit factor? Is 0.130 is high enough?
 

carabuser

Lieutenant
Oct 2, 2019
548
1
410
0
UK
Ride
Z4 35i & 335i
@carabuser I didn't know that Boost Ceiling changes too once you rescale into 3 cell. I thought that it's a raw boost limiter. Can you approve/reject this message? Is there any specific 3 cell related rescale calculation for boost ceiling?

Do I copy you correctly? This means to raise load target high enough so load actual won't be physically able to reach it, and control (pegg) it by boost ceiling considering 3 cell scaling application?
1) Set boost 1.28 (should work for 24 psi)
2) Raise BLM (Is BLM ceiling 3 OK?)
3) There are not much info on what is Load limit factor? Is 0.130 is high enough?
So to use the 3 cell scaling with MHD you need an MBoost license.

Mboost allows the real boost target in the DME to go up to 22.3PSI assuming sea level conditions.
Since you are wanting to target above that you are then scaling the TMAP, the DME doesn't know about that, MHD just corrects your log data to show the true boost.

I don't know if MHD corrects the boost ceiling param when writing. You would have to test that. I assume it does but I've never used scaling on my own cars.

BLM and load limit factor are just limiters for the load target. They are designed to allow smooth ramping of the load target to make the car drive better. Most tuners just set them to 3.0 for BLM and 0.1 for load limit factor. That should be enough to keep them out the way.
 

Sava666

Specialist
Dec 14, 2020
75
11
0
So to use the 3 cell scaling with MHD you need an MBoost license.

Mboost allows the real boost target in the DME to go up to 22.3PSI assuming sea level conditions.
Since you are wanting to target above that you are then scaling the TMAP, the DME doesn't know about that, MHD just corrects your log data to show the true boost.

I don't know if MHD corrects the boost ceiling param when writing. You would have to test that. I assume it does but I've never used scaling on my own cars.

BLM and load limit factor are just limiters for the load target. They are designed to allow smooth ramping of the load target to make the car drive better. Most tuners just set them to 3.0 for BLM and 0.1 for load limit factor. That should be enough to keep them out the way.
Yeah, I have Mboost.
No, MHD doesn't change boost ceiling. You need to do it manually. I read some post where people left it like 1.28 to hit 24ish psi(3 cell). While with 1.50 - it always around 28-30psi.
Thanks for the tips. I'll try the "dirty" way )))
Will report back in 20 days. I'm at hitch right now.
 
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