NefMoto

Hi there,

so I gathered now some Information about tuning a ECU and started to create my first "tune" for my S4 B5.
But I have the Problem, that when I drive full throttle, my boost only rises up to ~1bar (14,5 Psi), but it should rise up to ~1,28 Bar (18,5 PSi).
Can anybody tell me, what I forgot ?
In the following Picture are my Settings:


(https://www2.pic-upload.de/img/35705618/Unbenannt.png) (https://www.pic-upload.de)

Thanks in advance!

Have you recorded any logs that you would like to share?

No sorry,

If I have to post logs, I can do this only in the next few days, not today.

If you are unable to take logs, you're not going to be able to do anything.

I can do logs, but not today cause I am not at home now...

What should I log, only boost or some other stuff, too?

If you are using ME7L (and you had better not be planning on posting VCDS logs) why would you log only boost when it can literally practially log everything you'll ever need at the same time?

So which variables are for interest in Me7 logger?
There are no variables like ldrxn.
Which are the variables for boost?

http://files.s4wiki.com/ME7L-ecu/
https://github.com/nyetwurk/ME7L/tree/master/ecus
https://github.com/nyetwurk/ME7L/tree/master/logs

Incidentally, all of this information is in the FR.

You can see exactly what variables come from what table.

Look at the FR, look for LDRXN. The variable that comes out of LDRXN is immediately obvious.

Okay, I take a look in the Funktionsrahmen, then I will log boost.

btw this is my go to list

https://github.com/nyetwurk/ME7L/blob/master/logs/typical.lst

Why do you think it'll go to 18.5psi?

Cause my LDRXN is on highest load 198 and from there it is slightly falling down. 198 LDRXN are 1,28Bar (18,5 PSI).
But I never become this 18PSI even on higher loads, if I go full throttel on ~3000 RPM it rises up to ~1,1 bar (~16PSI).

I should log this, then we see more, actually I read it only from my Boostgauge in the Car itself.
 

Will it make that boost at that RPM?

Did you read the bit in the Wiki where it says:
Approximation
That isn't to say it's not possible to get a (very) rough approximation of the boost you'll see based on your chosen LDRXN.

requested boost=10*(LDRXN)+300mbar

Not to mention the fact you're complaining about missing 2.5psi, obviously don't have a calibrated boost gauge, obviously ignoring the fact the needle has a thickness and won't be 16 dead on or the fact the weather, the alignment of the sun and the moon and everything else dictates what you're requested actually is.

Also assuming you have absolutely no leaks whatsover.

I mean, logs would be amazing.

Maybe he didn't make 1,2bar at 2250 rpm but on 3000 he should make it.

Yes I read that and I know that there are many factors e.g. the alignment of the stars and the moon ;)

I have orientated me on the community project and there, the settings are similar.
http://nefariousmotorsports.com/forum/index.php?topic=6695.525

On Page 36 FlyboyS4 posted a log from his boost and you can see it runs up to 18 Psi and


The thing is, I want to tune my ignition for optimal use with Super98, but before that, the boost should run as desired.

Doesn't mean a damn thing until you either log the entire req load->boost conversion path or just up req load until you get what you want.

Logs are in the attachments.

Got some wired effects, if I am in 3th gear and go full throttel from under 1500rpm, the boost rises at ~3000rpm a short time to high and goes then instantly to much down until it picks up cuorage again.
You can see it in the log "3th gear full"

Is it maybe, because the Wastegates are completely open because he couldn't generate the desired boost, but then he become enought rpm for this pressure and the Wastegates didn't shut fast enought ?

(https://www2.pic-upload.de/img/35796162/Unbenannt.png) (https://www.pic-upload.de)


Half 3th gear from over 1500rpm

(https://www2.pic-upload.de/img/35796155/Unbenannt.png) (https://www.pic-upload.de)

You're going to have to do a bit of PID tuning.

It isn't easy.

Long story short, try pulling a bit of IMX or adding to Q2 to numb the overshoot.

S4 wiki says to change Q2 only as last resort, I first try to decrease KFLDIMX by -5 on 3000 - 3500 rpm.
Hope thats not to much, but I will see.

Okay, that didn't work...

In the Funktionsrahmen is described the following (I try to translate, you can see original text in attachments): "On problems with overshots [...] it should be tryed to hold up against it with big KFLDRQ2 values in conjunction with slightly bigger LDRQ0DY values."

Now I have to ask, which are good values to try that ?
Has anybody experience with that ?
 

So I am really at the End with my knowledge, I don't know what to do anymore, I hope, someone could help me.
First, I got no Overshot Problem anymore.

My Problem is, the Boost will not follow LDRXN, and the weird thing is, the DesiredBoost dosn't follow LDRXN, too as you can see in the new Log (And yes I know, that I have to lower Ignition a bit at higher RPM).

The funny thing is, in higher gears (5 & 6) I came to ~ 1.3 Bar boost.
In the lower ones maximum ~1,1 sometimes a bit less.

I Am not sure if it is a Software or a Hardware Problem.
So because of that, I did a lot of Troubleshooting:
- I checked the Boost System for leaks, but it is in good conditions, no leaks.
- I replaced the N75 with a brand new one.
- I tried it with putting off the connector to the air mass flowmeter.
- I looked if VCDS Boost Value is the same like my Boost gauge and it is.
- I put off the hose from N75 to the Wastegates and I easily became 1,5 bar boost (there could be much more, but I think the Turbos didn't like it).
- I have changed KFMIRL a lot of times with different Values
- I have changed KFMIOP with different Values

Maybe someone can look at my File in the Attachments
I don't know why, but I can't upload it here as Attachment, so here is a Onedrive link with the files:
https://1drv.ms/f/s!Av8z8olOxJKJxChgsu817HIperkB (https://1drv.ms/f/s!Av8z8olOxJKJxChgsu817HIperkB)

WTF I see no log file there.

I don't know why you keep saying "DesiredBoost dosn't follow LDRXN" without providing actual information about the load->req boost path.

There is one csv File in there.  ???


If you see the log, you see what I mean.


Edit:
(https://www2.pic-upload.de/thumb/35877309/Unbenannt.png) (https://www.pic-upload.de/view-35877309/Unbenannt.png.html)

I am also not shure, how the Wastegate Duty Cycle should look like.

ah never mind, my browser was being dumb, it only showed the preview. Reviewing the logs now.

rlsol is following rlmax perfectly.

rlmx however is much higher than rlmax.

Assuming ldrlts isn't interfering (KFLDHBN), the other possible interventions between rlmx and rlmax are frxta (IAT), frxt (tmot), fldrrx_w (KR), ldrlms (LDPBN, but only if B_brlmx is set), and LDORXN (but only on E_ldo).

The answer is ldrlts (HBN).

New section added to wiki:
https://s4wiki.com/wiki/Tuning#Boost_.28rlsol.29_intervention_via_rlmax

Which was already mentioned in the existing LDRXN section:


BTW all of this is in LDRLMX 3.100 in the FR on page 855

Hi Nyet,

thanks for your explanation!

Okay, I will try to increase KFLDHBN and try it again.

How could you show the Parameters like ldrlts_w in the ECUxPlot ?
I can't find them

Its LITERALLY in the section i linked above, in the QUOTE i made above, and in the aliases file in ME7L, and in the tooltips of ECUXPlot

Also see Options->Use alternate column names in ECUXPlot if you want to display the real ME7L names in the plot

Got it, thanks !

So increased KFLDHBN to FF but no changes.
I forgot on the ride my notebook for taking logs, so I will do this tomorrow.
I will also check my N75 again.

Okay, so I set my KFLDHBN to max that this can't limit again.
If my Boost runs like i want it, I will set it back to the desired Values, that my Turbos get protected for to much boost.

But only KFLDHBN didn't change anything, I have now increased KFLDIMX, but I think it was to much after 4000RPM.
As you can see in the new log, from 4000RPM desired boost goes much to high and WGDC goes to ~95%, then it goes to WGDC 10% but I can't see a DTC with boost error in VCDS.
I will lower DIMX from 4000rpm a bit and try it again and hope, that my desired boost gets lower at high RPM.
Also in this Log, LDRXN is set to 215 from 2500 until 4000

You got limp because of positive deviation.

Why would changing DIMX lower requested boost?

Yes thats a good Question but the question should be, "why is my requested boost higher with higher DIMX ?"
The funny thing is, in last logs, my requested boost was not so high.
Now with increased DIMX its higher  ???

I doubt that is the case. Log the variables I mentioned above in back to back logs with different IMX. Req boost can be changed by any number of things, including conditions, but DIMX is not one of them.

So my Problem is, that ChargeLimitTurboProtection didn't change, equal if I put KFLDHBN as high as possible or just slightly higher the LDRXN.
Boost never follows Specified Engine Load, is it possbile that there are other Values which have to be changed that "ldrlts" gets higher ?

also my WGDC gets from ~5800RPM to 95% and after some time Engine becomes emergency operation I lowered boost but the problem is still there.
I think I have to lower boost from 5800 - 7000 a bit more.

I flashed my original Software again and logged it to exclude Hardware Problems, there runs everything fine, so it have to be a Software issue.

Log files are here:
https://1drv.ms/f/s!Av8z8olOxJKJxChgsu817HIperkB (https://1drv.ms/f/s!Av8z8olOxJKJxChgsu817HIperkB)

I don't have the FR handy but ldrlts follows directly from HBN AFAIK. If i missed something, look in the FR.

Or maybe your HBN location is wrong?

Got the FR in front of me now. Look at page 855

Also perhaps try 551M instead of 551G. The HBN location in the public .xdf should be right.