Can anyone help me with tuning basics before I blow up my n54?

[CantSitStill]

OK so this is my first attempt at a flash-only tune. I have read up for hours and cobbled together a tune. An embarrassing one but we all have to start somewhere....

Thankfully my engine survived this but as you can see my boost target is shooting up and i cant work out why. Which im sure is down to my limited knowledge at this point. It certainly never felt like it hit 29psi but thats what the logs and target suggest.

I was trying to start off with something that could boost up to about 25psi but i had reduced a bit to start. I thought a load target of 205 ish would be about 24 psi if i set the boost ceiling at 1.8 bar.

What is really confusing me is how i managed to target more than the "boost ceiling" i had set to 1.8 bar? and how a load of 192 was targeting 28.7 psi of boost. As far as i can see PID was doing what is was supposed to be doing within the limits but i dont get how i ended up with such a high target, its like something is scaled wrong. The only thing i can think is that the N20 sensor limit of 36psi is now the new "boost ceiling" and thats why a load of 192 could be somewhere as high as 28.7?? Am i missing something with what i need to do with the n20 sensor.

datazap.me | Stuie1982 | Stu v1 MHD+

datazap.me

Can someone educate me please? I have attached a bunch of tables that might help.

 

[CantSitStill]

I think i worked it out from another post about having to scale the load targets over 10psi. 175 should give me the correct boost target. I read something about the boost ceiling needing to be scaled as well so the standard 1.28 is now 24-25psi?

 

[carabuser]

If you are scaling the tmap to inflate boost then you need to account for that in the tune.

The DME will see 16psi when you are actually making 26psi. So you would need a ceiling if 17psi to limit the boost to 28psi. Those are just example figures, you need to calculate the actual numbers or just use trial and error.

 

[CantSitStill]

If you are scaling the tmap to inflate boost then you need to account for that in the tune.

The DME will see 16psi when you are actually making 26psi. So you would need a ceiling if 17psi to limit the boost to 28psi. Those are just example figures, you need to calculate the actual numbers or just use trial and error.

Thanks!!, I think I'm starting to understand what I need to do with the load/boost tables. I see a mention that I need to rescale any other tables using load. Many of the tables have the same values over 145 loads so do I need to do anything for those or just leave those?

For example the fuel scalar I can leave, but the load to torque limit table and vanos, how do I scale that?

 

[BEAT_ITN54]

Download the new mhd+ bins and use new boost target tables. Set load out of the way and then start working on airflow and fuel.

 

[CantSitStill]

Download the new mhd+ bins and use new boost target tables. Set load out of the way and then start working on airflow and fuel.

Thanks just checked the guide out and looks way simpler. So raise the load target up so its never really met and set boost on the custom WGDC tables

 

[carabuser]

I think tuning the boost like that is sub optimal. The new MHD+ tables are really just a shortcut for people that don't understand the original DME logic.

Having boost target detached from the load target like that would make the car drive likes it's on an external boost controller. Not a problem if you just use it on the drag strip but for track or even daily driving it would be crap.

 

[CantSitStill]

Mmmm I daily drive mine and would be pissed off if it was under power one hot day. Does the below not suggest the DME can still increase the boost based on conditions, assuming its under the boost target or ceiling?

N54 Specific Custom WGDC Control Details
To use this control scheme in place of the limited OEM airflow based model, you must set the
Enable Custom WGDC Override toggle in the MHD+ Config folder to 01. This activates the
tables in the Custom Base Tables > WGDC folder, whose output overrides the near final WGDC
output (ECT adder is still applied, as well as battery voltage correction which should remain).
The tables, and their flow, is as follows:

1. WGDC Base (Custom) [or WGDC Base (Custom) (Antilag) if antilag is active] is looked
up, with axis inputs of RPM and MHD+ Boost Target. Here again, the Boost Target axis
is special as described in the boost ceiling section. You can enter actual PSI values up
to your 3-cell scaled TMAP maximum. The output of this can be seen when logging the
MHD+ WGDC Base parameter.

2. WGDC P-Factor (Custom) is looked up, with axis inputs of RPM and MHD+ Boost Error.
The Boost error axis here is also special just like the Boost Target axis of the WGDC
Base (Custom) table, except it is signed and can have positive or negative values. The
output of this table can be seen when logging the MHD+ WGDC P-Factor parameter.

3. WGDC D-Factor (Custom) is looked up, with axis inputs of MHD+ Boost Error and MHD+
Boost Error Grad. Both axes here are special just like the Boost Target axis of the WGDC
Base (Custom) table, except they are signed and can have positive or negative values.
The output of this table can be seen when logging the MHD+ WGDC D-Factor parameter.

4. If current Load Actual >= Min Load Threshold for P/D Factors table value, the P and D
factors are added to the MHD+ WGDC Base value, which after the OEM ECT adder and
batt volt. correction are applied, can be logged as the normal WGDC % Bank 1 / 2.

 

[BEAT_ITN54]

But the target isn't detached from load. The new table just acts as a load ceiling for the set target. Load request can be maxed but will still only reach what the target demands. Everything before target still is still adjusting for ambient variables and behaves the same. It's a good safety net for new people and let's you try different targets with less guess work. Once you have and idea of what load you need for your ideal target you can always go back to the original logic like I had planned but haven't really had a reason too as it drives great. I briefly tried the custom wgdc as well but it really only seems useful for single turbo guys.

 

[carabuser]

But the target isn't detached from load. The new table just acts as a load ceiling for the set target. Load request can be maxed but will still only reach what the target demands. Everything before target still is still adjusting for ambient variables and behaves the same. It's a good safety net for new people and let's you try different targets with less guess work. Once you have and idea of what load you need for your ideal target you can always go back to the original logic like I had planned but haven't really had a reason too as it drives great. I briefly tried the custom wgdc as well but it really only seems useful for single turbo guys.

If the VE model determines the car needs 22psi in the manifold to achieve your load target and you have a boost ceiling set to 16psi then the target is completely detached.

It also means that you get the same boost target at 50% torque request as you would at 100%.

The only purpose of the boost ceiling parameter is a safety during development hence why BMW set it to max in the stock cal. If you use it as you mentioned there's no issues, you set the ceiling to the absolute max you want to see as a safety and then gradually tune the car beneath that ceiling.

 

[CantSitStill]

In my recent tuning with one of the popular tuners there is a boost target set that's perfectly flat, in my old tunes from the same guy the boost target is variable and tracks the boost.

datazap.me | Stuie1982 | V18

datazap.me

How has the tuner managed the flat boost target? I assume by using the same boost ceiling per gear MHD+ tables?

Like if the boost target (ceiling) is set above what the DME needs to use by say 2 psi, then is the VE model not still in action below that? So adjusts boost down where needed and up so long as its not hitting the ceiling?

Maybe I'm not understanding how these new tables are used but here is my first attempt at using them:

datazap.me | Stuie1982 | stu v3

datazap.me

If I increase the ceiling in these new tables will it increase the boost automatically by referencing more setpoint in the base table? Still trying to work out the relationship between the 2 tables.

Thanks

 

[BEAT_ITN54]

In my recent tuning with one of the popular tuners there is a boost target set that's perfectly flat, in my old tunes from the same guy the boost target is variable and tracks the boost.

datazap.me | Stuie1982 | V18

datazap.me

How has the tuner managed the flat boost target? I assume by using the same boost ceiling per gear MHD+ tables?

Like if the boost target (ceiling) is set above what the DME needs to use by say 2 psi, then is the VE model not still in action below that? So adjusts boost down where needed and up so long as its not hitting the ceiling?

Maybe I'm not understanding how these new tables are used but here is my first attempt at using them:

datazap.me | Stuie1982 | stu v3

datazap.me

If I increase the ceiling in these new tables will it increase the boost automatically by referencing more setpoint in the base table? Still trying to work out the relationship between the 2 tables.

Thanks

You will still need too adjust wastegate for the target. Iv gone back and forth between the two and have yet to find any noticeable drivabilty issues. I keep load request close to what it should be while using the new tables to keep boost lower where traction and hpfp struggle the most.

 

[CantSitStill]

I have a hopefully basic question here for something i don't understand:

datazap.me | Stuie1982 | v14 stu good logs 3

datazap.me

The car drives like sh!t just now part acceleration and I'm missing something. It feels like the boost is on or off so if you try and drive it "sporty" it always tries to hit max boost, especially noticeable when the transmission changes up and it bogs down as it's trying to get high boost but it changes up during it and feels like its been choaked.

In that part acceleration log above you can see where it happens. I have a consistent accelerator peddle but the DME suddenly targets really high load despite me keeping about 20-30% throttle. I have tried the linear throttle option in MHD and it's the same.

So my question is what is it that translates the accelerator pedal into load request? How has the DME decided to target full load at 30% accelerator? What tables should i look at. I know about the torque request tables but i dont see how they link to load requests.

Thanks