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Author Topic: KFMIRL, KFMIOP, KFMIZUOF - Torque Monitoring sanity check  (Read 191491 times)
berTTos
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« on: September 04, 2011, 06:58:37 PM »

I've been running with KFMIRL altered to increase loads at all RPMs and % Torque Requested but with KFMIOP stock and the car ran like crap.  Torque monitoring was constantly intervening resulting in crappy part throttle response.  So I adjusted RLVMXN, RLVSMXN and KFMIZUFIL which reduced the part throttle lumpiness but I then began experiencing throttle-cut with Torque Monitor Code (Control Limit Exceeded) during part throttle acceleration from low RPMs and Torque monitoring was still intervening at cruise resulting in crazy Fuel Trims, misfires, rough running and just a generally poor part throttle experience.

So - I switch KFMIRL to stock except the last 3 columns which are smoothed to 240.  Result? Car runs great.  Smooth as can be albeit with a slightly dulled throttle response (Torque monitoring smoothing things out).

I'm trying to understand the ME7 Torque Model and have come to the conclusion that one cannot increase KFMIRL without sufficiently altering KFMIOP UNLESS one decided to 'disable' Torque Monitoring via KFMIZUOF.

Here is what I think I understand - If a KFMIRL load value deviates from the corresponding %Torque value in KFMIOP (which should be the inverse of KFMIRL) more than the allowed deviation from KFMIZUOF (which is zero for much of the table) then ME7 intervenes.  If this assumption is correct then increasing load values in KFMIRL and leaving KFMIOP stock will result in deviations much greater than what is defined in KFMIZUOF and the car will run like crap as ME7 tries to get things in line.

So - our options are -
1. Leave all but the last 2 or 3 columns of KFMIRL stock and KFMIOP and KFMIZUOF stock. Enjoy the silken rocket driving experience.
2. Raise Load values in KFMIRL across the board and properly tune KFMIOP to match and leave KFMIZUOF stock.  In this scenario greater loads are produced earlier but the Torque Model is still perfectly functional and able to give stock-like refinement.
3. Raise KFMIRL load values and leave KFMIOP stock but FF KFMIZUOF across the entire table effectively disabling Torque Monitoring (also I believe there are 2 scalar values related to temp thresholds which need to be altered).  I have not tried this so I don't know how wild the throttle is in this scenario.

Am I on the right track?  Am I completely wrong?

**addition**
Here are the values required to deactivate Torque Monitoring (per the FR).  I have not tried these:

Table KFMIZUOF = 99.6% for all base points
Z - 11619 * 0.390625
X - 1008E * 40
Y - 1166D * 0.390625

Scalar TMNSMN  = -48 C
11676 * 0.75 - 48

Scalar TANSMN  = -48 C
11675 * 0.75 - 48

« Last Edit: September 08, 2011, 03:40:59 PM by berTTos » Logged
TTQS
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« Reply #1 on: September 05, 2011, 05:18:15 AM »

Hi.

I've just been working through the FUEDK and MDFAW modules to try to understand the torque oriented structure better. There is a note in MDFUE 8.50 which states that KFMIRL and KFMIOP are the inverse of each other (as you have recognised).

I haven't fully digested the implications of this yet, but that statement would indicate to me that the entries in both maps must complement each other so that if you adjust one, you must ensure that the changes are suitably reflected in the other, or else the ECU will see something is amiss.

Therefore option 2 is preferred. You seem to have a good handle on this issue already.

TTQS
« Last Edit: January 16, 2012, 03:17:45 AM by TTQS » Logged
berTTos
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« Reply #2 on: September 05, 2011, 12:04:59 PM »


Therefore option 2 is preferred.


Thanks for the reply, Doug.  I also believe option 2 is preferred.  That said, let's reflect on how this is to be accomplished. For this example I am using a modified KFMIRL (load values increased by 25% across the table) and a stock KFMIOP both from an S4 Mbox -

KFMIRL -
x axis = % Torque requested
y axis = RPM
Output = Target Filling (Load)

KFMIOP -
x axis = Cylinder Filling (I believe this is actual Load as calculated by ME7)
y axis = RPM
Output = % Torque

If I request 80% of available Torque at 4000 RPM this resuts in a Load Value of 205.83 according to this altered KFMIRL


This will hopefully produce actual Load close to the requested value, however I believe that there are many occassions where actual Load will exceed requested for brief periods.  Let's suppose that the actual calculated value is 205.83, which if we look up in KFMIOP (stock) should correspond to 89.46 %Torque at 4000 RPM.  This is a +9.46% deviation in %Torque, assuming that actual Load is EXACTLY what was requested.  According to KFMIOP, this amount of Load should not be produced at 80% Requested Torque but rather at 89.46% Requested Torque.



 According to KFMIOP 80% Torque Request should result in a Load Value of between 144.75 and 168 (I assume that the 144.75 value is used until requested torque increases to 81.03%) and this results in Torque Monitoring intervening to reduce Actual Load.  The driver experiences jumpiness and stuttering at part throttle acceleration as ME7 tries to achieve requested Torque one moment and attempts to reduce Torque the next.

This scenario suggests that the appropriate strategy is to LOWER the output values in KFMIOP so that a given Load Value corresponds to a LOWER %Torque requested (effectively, for a given %Torque Requested a higher Load value is considered optimal). However, I have examined several professionally tuned files where the tuner has done the opposite (KFMIOP values are raised).  Either I am not understanding the model or the tuners are misinformed (GIAC comes to mind - and this does make some sense if we remember back to many of their early files having issues with Torque Monitoring throttle cut.)

Am I on the right track?
« Last Edit: September 05, 2011, 01:16:01 PM by berTTos » Logged
TTQS
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« Reply #3 on: September 06, 2011, 01:02:24 AM »

Hi BerTTos.

I'll need to consider the various modules in more detail because there are some issues which aren't clear, particularly why the maximum load on KFMIOP is 191 which is much less than the maximum requested load in KFMIRL (recognising that KFMIOP is the basic torque at basic lambda and basic ignition angle). I also note that the maps are the same in both TT 1.8T 225 and 240 PS stock files but LDRXN is modified. Perhaps the differences are not significant enough to warrant modifying these maps or perhaps there is no need to do so if the turbo is the same... I.e. the maximum load is set by what the turbo can achieve so no point in trying to increase it beyond that.

Nevertheless, the approach you suggest seems logical to me.

The map values are interpolation points so there should be a smooth transition between them.

I have been limited in my understanding from the get go because I have not been able or willing to examine known good professional tunes, especially my own. Hopefully I will rectify that situation this fall.

Thanks for a stimulating discussion and very timely since I was just looking into this on the day you posted.

TTQS
« Last Edit: January 16, 2012, 03:18:57 AM by TTQS » Logged
judeisnotobscure
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« Reply #4 on: September 06, 2011, 06:42:33 AM »

This is good discussion, thank you... I think i'm having issues with this is well.  It now has my full attention.   I'm going to give these modules a good read this week and see what i come up with. 
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NOTORIOUS VR
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« Reply #5 on: September 06, 2011, 07:24:08 AM »

Great discussion guys!

I've only got one thing to say at this point since I don't know anything... but getting hung up on the one line in the FR saying it is the inverse might now be 100% right in the sense that it's supposed to be made smaller.

I have an supposed MTM (not sure if it really is or not) H-box file where KFMIRL is much larger then stock, and KFMIOP is also completely different and has larger numbers then stock.  That file is one of the smoothest driving files I've ever had.
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« Reply #6 on: September 06, 2011, 12:42:29 PM »

I've been struggling with this as well, particularly the following:

1) As bertos pointed out, stock IOP map doesn't seem to be the proper inverse of IRL *everywhere*, just in most places.
2) Increasing IRL would seem to indicate the proper response is to LOWER IOP, not increase it.
3) Actually logging req torque vs actual torque during (what I think is) torque intervention in timing did NOT show that actual > req!

A few things I would like to add though

Never trust what "another tuner" has done. EVER.

IMO this is the #1 lesson that nobody seems to learn; NEVER copy somebody elses map unless you understand 100% why. Doing anything else leads to madness; you have a bunch of tuners just saying "trust me, this voodoo works, but I cant explain why" and later it becomes a "truth". I believe increasing IOP to reflect IRL is one of those things that tuners do that just makes no sense.

Also just because "my car runs great with map X", doesn't mean you did the right thing Smiley

There are a half a dozen things OTHER than IOP that can cause torque/timing intervention. I'm in the midst of trying to figure out what to log to find them all.

Here is my short list

etazwbm
miasrl_l
miasrs_w
miist_w
misol_w
zwbasar_0-3
zwist
zwopt
zwout

PLEASE if you see torque intervention, add these to your ME7L config and post em!

Finally, I am thinking of writing a program to take a IRL and convert it to an IOP.

Given #1, the irony would be that it would NOT produce a stock IOP given a stock IRL Smiley
« Last Edit: September 06, 2011, 01:30:10 PM by nyet » Logged

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« Reply #7 on: September 06, 2011, 12:48:58 PM »

Oh! One more thing.

Load != torque

Keep in mind the *torque* measurement is a % of optimal torque, regardless of current load (or size of turbos, boost pressure, etc, etc) and is (mostly) dependent on the difference between optimal timing, and actual timing.
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« Reply #8 on: September 06, 2011, 12:52:24 PM »

IMHO, the best way to sort out some of remaining mysteries is by variable tracking with a datalogger. That being said, there are alot of variables that were not ouput by Setzi's ME7Info and would have to be added manually.
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« Reply #9 on: September 06, 2011, 01:09:16 PM »

I've been struggling with this as well, particularly the following:

1) As bertos pointed out, stock IOP map doesn't seem to be the proper inverse of IRL

Again, I am not so sure it is supposed to be the true "inverse" I think the FR is a little misleading in that sense. It just doesn't make sense IMO.

Quote
2) Increasing IRL would seem to indicate the proper response is to LOWER IOP, not increase it.

Why do you believe this to be true?  

Quote
Never trust what "another tuner" has done. EVER.

Absolutely...

Just for info... here is the maps in question for the H-box:


« Last Edit: September 06, 2011, 01:25:27 PM by NOTORIOUS VR » Logged

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« Reply #10 on: September 06, 2011, 01:17:05 PM »

Again, I am not so sure it is supposed to be the true "inverse" I think the FR is a little misleading in that sense. It just doesn't make sense IMO.

Not literal inverse. See Berttos's analysis.

Quote
2) Increasing IRL would seem to indicate the proper response is to LOWER IOP, not increase it.

Basically, if you increase IRL, it means that req load is higher for a given req torque, which means for the SAME load, act torque (IOP) needs to be lower to prevent req torque < actual torque.

Unless, like Bert, i am woefully misreading the FR
« Last Edit: September 06, 2011, 01:19:44 PM by nyet » Logged

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judeisnotobscure
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« Reply #11 on: September 06, 2011, 02:36:16 PM »

I've come to the same conclusion after reading a bit, the fr and this discussion.  so I did some testing.  Kfmirl goes up and kfmiop must go down.   I don't agree that it's the literal inverse function as the document says.   
I increased kfmirl about 25% but leaving the 4 lowest columns stock.... then i matched up the correlating columns on kfmiop and decreased them by 10%.   This took the car from "meh" part throttle to very smooth. (stage 3 b5 s4)
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« Reply #12 on: September 06, 2011, 02:42:44 PM »

I don't agree that it's the literal inverse function as the document says.   

Actually, I want to amend my position Smiley

I believe the intent is for IOP to provide the *literal* inverse function that IRL provides (inverse meaning inverse FUNCTION, not arithmetic inverse).

i.e.

IRL provides load = f(rpm,tq)
OIP provices tq = g(rpm,load)

where g() = f^-1()

Like I said though, there are areas in the stock IOP that don't do this.
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« Reply #13 on: September 06, 2011, 02:47:15 PM »

Oh, and one more thing: if you universally increase the output (load) of IRL by a fixed %, can you just increase the load axis of IOP across the board, rather than decreasing the output (tq)? Might be a bit easier (but you'd have to see what else shares that axis). Also, I'm still trying to figure out what affect MAF scaling has on this as well. It could be that if you underscale your MAF enough, the actual load is low enough that actual torque is never high enough to cause problems.
« Last Edit: September 06, 2011, 02:52:05 PM by nyet » Logged

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« Reply #14 on: September 06, 2011, 02:50:07 PM »

Oh, and one more thing: the output of IOP goes into the *actual* torque measurement (after lambda/timing adjustment)!
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