NefMoto

Does anyone have an explanation for this?
Boost is 1.9 bar right now. Goes lean in mid range due to TE being basically constant, then rich up top. RS4 MAF.

What freaks me out are 1) LOAD, 2) TE
KFKHFM and FKKVS are all 1.
MLHFM copy pasted from RS4.

Some pics:

The MAF mass-airflow graph looks pretty normal to me, but the load and IPW definitely do not!

Any ideas as to what is going on?

Are you using the actual rs4 airbox flap control?  I know Thomas has turned that into a PWM-type thing.  I ask this because having compared the MLHFM's, I'm practically guaranteeing you that Audi fudged the upper part of the curvature to account for the increased airflow.
I could dig it up, but I did a log-log plot of the various MLHFM tables, and only the B5 RS4 displayed this excess Kg/Hr curvature profile I'm trying to describe here.

What's your KFLF?  Stock RS4?

This is a 4 banger with ME7.5 ;)
I think KFLF does not really come into it, because rl_w is what gets capped out. If you look at the graphs carefully - rl_w and injection time top out at exactly the same spot.
I am wondering if pirg_w could play a role...

OK then, if this is a 4-banger with a converted MLFHM from the RS4 then you almost definitely need to correct the RS4 MLHFM profile.  Let me see if I can dig up the spreadsheet I used to do my ad-hoc analysis of this MAF.

This is what AFR looks like:

Sorry, I just don't see it being any kind of profile. It is a hard cap on load at 1.3 bar and thus injection time.
The RS4 graph looks fairly smooth.

This is pressure related if anything (=cylinder charge), not flow related.

I am wondering if FPVMXN2 could have something to do with it.

Here's what I was thinking.   Scale your MAF as follows and rerun without other changes.  I think on second thought that my LambdaPoint=0.0 is correct. Maybe not?  ha.

You are saying to lower the values. I am going to be even more lean then.
It is definitely pressure related, every time I hit 220 load, it caps it.

I'll try that map I mentioned and see if it helps anything.

Very interesting.  Well, I agree, but if you have 440 g/s it's actually less, say 400 g/s, and yes you'd run lean if you did this holding other things constant. However, you'd adjust this and also adjust KRKTE at the same time to get the WOT you want.  The re-centered KRKTE versus your current setup should have lower fueling variance because the metering is more precise. It'll be interesting to see the result of this thread regardless.

Yes. I saw this as well when maxing load with a built motor with larger displacement and stock kumsrl.

The only solution i have is underscale MAF, and bring up KRKTE (if your displacement is stock)

I don't think KUMSRL is the culprit. It is definitely a MAX cap somewhere.

kfldhbn?  kfmirl?

For a large displacement motor, it is.

For your application i'd just underscale the MAF.

It's really simple actually.
ps_w hits 65535.

rlroh_w is fine, it rises as it should.

Yeah, I need to underscale the MAF :(

Set KFKHFM to 0.66 from 140 load and KFLF to 1.5 from the same point.
Everything is fine now.

This is a pretty annoying limitation though. And I am sure it can be easily circumvented in ASM by doing some divisions by 2...

From the graphs - rl_w now follows rlroh_w and ps_w no longer goes above 2200 mbar, thus load does not max out.

It's back to the age old limitation of 1.5 bar in the ECU. Ah well.

Wow. Thanks for actually tracking it down.

Someday we'll figure out how to either run an underscaled MAP, or fix the load limitation entirely :)

I didn't realize there was yet another limitation (ps_w) that wasn't based on MAP readings.

Would underscaling the MAP prevent ps_w from maxing out? Or is only calculated from load? I haven't checked the FR yet.

Yikes. I guess thats one way to skin a cat. Are you sure you can make that big of a discontinuity (even if it is compensated for by KFLF?)

I'd always thought it would be better to just underscale the MAF as a whole, and have load be underscaled everywhere, not just in some regions.

This works just fine. I don't see the point to under scale down low, as I would lose fine grained control and blow up part throttle.
Overscaling up top is fine, because this thing has a 1 bar wastegate spring and boost is 30 psi anyway, so the transition is really fast.
That said, I played with KFLF quite a bit just now on the airfield, and I got my fuel right where I want it, because I am linearizing the PID, I also had to do this with 0, 10, 20, 30, 40 etc duty cycle and actual follows requested nicely. This is a narrowband ECU as well.

As for fixing the problem entirely - it will need a simple ASM hack. Before rlroh_w goes into the integrator and gets transformed into ps_w and pbr_w, it should be divided by 2, then multiplied by 2 again.
ps_w is not important, what is important is pbr_w, and keeping it lower until we get back to rl_w. Underscaling the MAP will accomplish nothing at all, because ps_w is calculated from rlroh_w.

When I get some free time (usually in winter, when we have snow), then I will probably write this hack into the ECU. I rewrote tons of stuff on the older motronics to suit my needs as well - factory systems don't really like more than 200hp per liter ;)

Fantastic. I am VERY glad you found this. I look forwards to seeing your hack.

Then, we get to talk about MAP solutions? :)

I didn't think about this solution! (
I agree keeping high resolution at low load is a good idea.
I may have to try it very soon.

BTW, which turbocharger are this logs referring to?

Precision 5857 SP

You can't fix this on a specific power output number. Other ECUs have some stepstones that limit you far before that ;)
 
I have wraped my head about this limit as well because my new setup is also excceding the MAP limit and I don't like underscaled load because you fuck up nearly everything with that.
I think the most elegant solution would be to completely underscale the pressures as the flow over the throttle plate is a function of PR before - after the plate. So something similar like running at high altitude with a "bigger displacement" engine. To get it completely right you have to touch some stuff but it will run with no negative side effects.
When my hardware is done in 3weeks I'll start testing and let you know how to do that.

Sure, go on...

For now this solution allowed me to dial in the mixture quite nicely, although I did need to do a lot of tweaking to the KFLF map.
But that might be also because my MAF is not linearized completely right.

Hard to tune unknown injectors with an unknown intake and a MAF where you can only copy paste MLHFM from RS4 and pray ;)

Thinking about this whole thing.

How many things would break just by setting KFURL 2x lower and adjusting the MAP sensor scaling 2x lower?
This would allow the ECU to read 4 bar boost, but at a double loss of precision.

Obviously the zero (atmospheric) point would have to be recalibrated and the relationship between the baro pressure and boost pressure, along with any axes that used boost/absolute pressure and maps, but I don't see anything impossible.

I will wait until my emulator arrives, and then try this on my RS4, and see how far I get before hitting a brick wall ;)

It is a bit more complicated but as you said nothing impossible. I have already made a list with stuff that has to be changed (mainly fho and ps-rl/rl-ps related). I'm on holidays this week but I can send you the list next week if you like so things will develope a bit faster as I'm not sure if I will be done with my hardware as planned

do I find a short summary how the other 8-byte limits like MAP in ME7 have been solved?
(I will check with search function meanwhile).

thanks.

No. This is all one big picture. You can't really solve one problem properly without solving the other  ;)

I can't think of any variable cap limits that have been solved.

Sure, I'll take that list...
I will be away for the first week of September, but after that I can spend some time on this, and with the emulator it will go a lot faster as well.

And yes, there is no good way to solve this without doing it properly. Or at least it's not worth it.
Just need to for example half the boost resolution precision... and adjust everything that references boost.

Also, it makes sense to do this on 551K, but not so much sense on M-box, etc. This is because if your load axes cap out at 191 on crucial maps you can't really tune properly anyway.
So you might as well underscale...

Thank you for pioneering this project.  As you know I'm actively trying to switch the M-box crowd to K-box with my own thread.
silentbob said it the best:  this is one big picture.  The community necessary to repair these tangible issues appears to continue growing...

how do 1.6++ bar engine mods work with ME7 properly without dirty hacks?

so the big picture "project" will be modifying the ECU that it work like stock and proper diagnostic, internal physics:

- underscale MAP, PU and all 16 bit pressure values by factor 2, find all references in calculation, maps, curves, values in parameter space and shift accordingly.
  Underscaled 16 bit should be still precise enough: better than 0.1 mbar

what about 8 bit occurrences?

do any stock ME7 exist with controlled boost over 1.55bar?

Pretty much all use fixed duty cycle or standalone boost control (in parallel, or alone).

They don't right now.
You underscale the MAF to keep LOAD sane, and used fixed DC in the last row of the duty map...
It works more or less OK, but of course spoolup could be improved by properly using the PID and underscaling LOAD takes a while to dial in, even if you only do it up top.

That said - on ECU's where all the load axes on maps like KFZW/KFZW2 are 8 bit, you will have to underscale load anyway on big power setups, because otherwise you can not control ignition over 191 load.
You can not solve the MAP limit without the LOAD limit though and vice versa, because these are connected.

silentbob, any luck with that list?
I got my emulator, and I got some time that I can dedicate to this problem.

I would need to start working on a base file...