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Author Topic: MED9.1.2 RS6 V10 Torque Intervention?  (Read 1347 times)
spacey3
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« on: September 21, 2022, 02:42:06 AM »

Hi folks! Hoping to get some help on this one, my personal RS6, TTE hybrids + usual supporting mods.

I'm getting some potentially odd torque intervention or something high RPM (above 5k) but only when letting off and getting back on the throttle quickly, so sometimes has an effect after gear changes or coming out of corners etc. If a pull is made from <5k RPM, all is well!

I've made sure KFMIOP/KFMIRL are correct, gone through and raised a ton of limiters even just for testing, turned off ARMD (TMAR, various TM tables, it drives a bit crappy with it off, but no difference to this issue), etc. It's not running out of fuel (at least doesn't appear to be, trims are good, if a little rich even), rail pressure isn't dropping, not overboosting, etc. Also the gearbox has been tuned and TL's raised etc. though I may have missed something there of course, there doesn't appear to be any interventions from there.

The logs are not great, they're only done with VCDS and potentially hard to read, but look for the oscillation after coming off the throttle and back on, which I imagine is insufficient for this level of problem, but they show at least that the problem is Load Request, rather than simply overboost or anything like that. In the meantime, I'm awaiting a Tactrix cable so I can use the VehiCal logger.

I feel like I'm missing something that I can't see! I've been wasting a lot of time in just flashing alone (over 30 mins per test!), so I'm happy to pay the usual pro's for any hints/solve it if need be Smiley Any help/hints/ideas would be appreciated! Also struggling to find an FR for the MED9.1.2 if anyone also has that so I could dig deeper Smiley
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prj
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« Reply #1 on: September 21, 2022, 04:40:57 AM »

Is the gearbox torque limit modified?

Also, use a proper logger. Mine will run you all of 100 EUR and you can log to you hearts content.
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spacey3
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« Reply #2 on: September 21, 2022, 05:27:21 AM »

Is the gearbox torque limit modified?

Also, use a proper logger. Mine will run you all of 100 EUR and you can log to you hearts content.

Thanks for chiming in prj!

I believe so, there's a bunch raised - MOTORMAX, MGETRMAX and the MHOTMODEMAX (for the lower/normal operating temp) tables. Though I see there's a couple of other potential limiters sitting around 800nm, worth bumping them all up? Does this kinda thing sound like the gearbox being unhappy?

Yes, I believe the VehiCal stuff is yours? As I mentioned, awaiting a Tactrix cable, unless a VCDS/VAS or other cable works.
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prj
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« Reply #3 on: September 21, 2022, 05:49:04 AM »

There's a few other things, but what you listed should be enough.
You need proper logger then you will see what is going on, VCDS is waste of time on these.

Before I made my logger I defined custom measuring blocks in the bin and logged that way, but ram logger is so much more powerful.
And you are not limited to 12 variables etc.

If you get this issue also on WOT, then you could be running out of injection window.
Especially if you don't have WMI. I made 1000hp with WMI and stock fuel system, but I had dual 1.2mm jets, which was accounting for over 15% of the fuel.
And injection window had to be extended a lot.

You will immediately be able to log and verify it with a ram logger though.
« Last Edit: September 21, 2022, 05:51:44 AM by prj » Logged

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spacey3
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« Reply #4 on: September 21, 2022, 05:58:16 AM »

I see others related to like up/downshifts and stuff, but these appear to be the core ones as you say.

Yea it's only WOT at high rpm, I also wondered if it was running out of injector, though the fuel trims actually start going rich towards the top end close to 10% (I assume mostly because WMI here also, not sure what hole size, but they're 440cc nozzles), but maybe I'm actually incorrect and it's running out as you say.

Injector timing is peaking at 6.75-7 from 5k onwards pretty much.

Nice to hear you can hit such figures with stock fuel system!

I'll definitely wait for the cable to get your logger going, it's not really worth the hassle messing with VCDS etc! I'm very accustomed to using the ME7Logger on my other car, so VCDS is pretty frustrating to me right now!
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prj
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« Reply #5 on: September 21, 2022, 06:33:16 AM »

You assume that it has to go lean.
It does not.

You need to read up a lot on how DI works and how MED9 and newer ECU's work.
It will limit load to run the maximum allowed injection window.

Lot of things to learn, ram logger + FR will help.
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spacey3
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« Reply #6 on: September 21, 2022, 06:49:58 AM »

You assume that it has to go lean.
It does not.

You need to read up a lot on how DI works and how MED9 and newer ECU's work.
It will limit load to run the maximum allowed injection window.

Lot of things to learn, ram logger + FR will help.

I literally just looked through the SOI/EOI stuff and worked out the injector window, it appears (I'm sure it'll be slightly +/- with any corrections) at 6k for example, I think I've worked out there's 6.66ms, which is clearly smaller than I need! Does that sound correct with your experiences off the top of your head?

With this info, and overlooking this, I now feel like an idiot, but that's why I'm here I guess! Smiley

I'll try sorting/testing this in the meantime whilst waiting for the cable for your logger anyway if I get a spare hour.

Talking of the FR, I've the 9.1 one that's floating about, but it does like quite different to 9.1.2 (though a lot of the fundamentals are the same). If you/anyone else who chimes in has the 9.1.2 one (for the TTRS/RS3 I believe?) available I'd be very appreciative!
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prj
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« Reply #7 on: September 21, 2022, 08:37:42 AM »

The whole DI thing is the same. You have some room to extend the window but you need to understand in which direction and why, for that knowledge about DI is needed. Actually the FR explains it very well as well, maybe google translate will help you with the German.
I never shared or asked for OEM data and I am not going to either, maybe someone else feels generous.
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spacey3
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« Reply #8 on: September 21, 2022, 08:46:35 AM »

The whole DI thing is the same. You have some room to extend the window but you need to understand in which direction and why, for that knowledge about DI is needed. Actually the FR explains it very well as well, maybe google translate will help you with the German.
I never shared or asked for OEM data and I am not going to either, maybe someone else feels generous.

That's cool! I appreciate your time and knowledge already!
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prj
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« Reply #9 on: September 22, 2022, 02:15:33 PM »

Here is what I got with and without WMI.
Without WMI the max was 840 on the 98 RON we get here, after that I was out of injection window if I wanted to target ~0.8 lambda.
Everything stock on car apart from turbos, exhaust, wmi and air filters.

The problem is also on the LPFP on these. And upgrading isn't straightforward, at least I wasn't aware of a straightforward upgrade when I was still tuning.
And if you fit e.g. LOBA HPFP's you get massive pressure overshoot when coming off throttle, that needs to be solved.

Better just max the stock system and run a ton of meth. After 1050hp you run into massive exhaust manifold flow issues anyway which is a pretty impossible thing to solve unless you want to cut the chassis.

« Last Edit: September 22, 2022, 02:18:52 PM by prj » Logged

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spacey3
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« Reply #10 on: September 23, 2022, 04:05:28 AM »

That's some mental figures for quite basic mod's! And seems the WMI has made a tremendous difference! Did a lot of that power come from timing you could run also then? I see most people (especially in the UK here, MRC etc.) insist on larger injectors etc. but it's nice to see things are possible if you think out of the box a little more.

Some good tips there on the HPFP etc. too. Yea I see my LPFP dropping quite a bit, down to ~3bar, I was thinking something would need to be done about that at some point.

As a follow up on the issue above, after taking your hint (and feeling terribly stupid), as a raw test I extended the EOI a little (I came across a very informative post of yours elsewhere about SOI/EOI) and leaned out to ~0.8 lambda (the request was previously 0.78 and was actually doing more like 0.76 before arbitrarily fixing up FKKVS a little just for a test also) and the 'surging' has all but gone! I think I just went down the rabbit hole of chasing torque interventions etc. without looking at the basic stuff first.

Time for me to look more into this one, thanks Prj! Smiley
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prj
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« Reply #11 on: September 23, 2022, 05:57:27 AM »

It's a combination of timing and the fact that you don't run out of injection window.

I don't think there's any point doing injectors or LPFP or any of that.
WMI is the solution, it costs maybe 5-10% of what you would need to do to get there without.
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