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Author Topic: The Basics of ME7 Tuning  (Read 2221 times)
CHRISTIANDOY
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« on: February 13, 2017, 02:35:41 PM »

This will be an ongoing thread of everything that I have learned from reading the tuning section of nefmoto to further understand the ME7 Motronic system.  I will start off by saying I am no expert and this document is my interpretation of everything that I have been exposed to thus far.  I borrow literature and information from both the S4 Tuning Wiki as well as nefmoto forum and nothing further. I would personally like to thank Nyet, Phila_dot, prj and ddillenger (May God rest your soul) as half of the information gathered would not have been possible without these fine folks.  I also want to extend my gratitude to thelastleroy for coming up with the community stage 1 and 2 threads .  Please for the love of God if anything I say here is wrong tell me so I can further my learning as well!

Ok, so say you’re a rookie (like myself) and are just thrown into this deep rainforest that is ME7 with no GPS.  All you have on you is a half washed away mapquest document from 2009 WYD? You scour endlessly for a rough idea of where to go next.  In the spirit of Nefmoto I am not asking before I have read, I am reading before I ask and trying to get at least a basic understanding.

So where the hell do we begin this crazy adventure?  How about with fueling.  The tuning wiki does a great job of encompassing this so this will for the most part be me wording out what I have gathered. For the sake of simplicity I will not be getting into situations that involve modifying for larger injectors, larger fuel pressure regulator and other adjustments to the fuel system.  This paper is more geared towards the individual that is just looking to do a basic Stage 1 or 2 remap with no fueling changes other than lambda request value alteration. 

The first map necessary for a stage 1 tune would be LAMFA (some would argue KFLF could also be changed, but throughout my readings I have learned to not touch this map unless absolutely necessary.  This map is a scaling factor for the conversion of a predicted load to relative fuel mass) .  Now this map, from my understanding, is active in specific situations and have built in delays which trigger them.  Specifically, LAMFA is delayed by TLAFA which is just a delay timer for LAMFA.  The stock value in my file was set to 1 (According to my damos this is a measure in seconds).  Changing this to zero would effectively remove the delay of the use of the LAMFA map thus it always remains active and the first determinant of fuel based operation in the ME7 fuel delivery system when requesting above 50% torque.  Obviously, there can be and are many other maps that can intervene with fueling.  You have internal functions which limit you to a lambda of 14.7 all the time unless there is intervention within one of the two maps (in my case) LAMFA or KFLBTS.  LAMFA displays its values in lambda where 14.7 AFR equates to 1.  To make this even clearer, if you go with a smaller number than 1 you will effectively be lowering your fuel request below the 14.7 mark which is richer (helps cool combustion event as well as prevent knock allowing you do make more power without the risk of damaging things).  If you raise the value of 1 upwards then you are going into lean territory which can put your engine at risk for damage as the temperatures in the cylinder will increase (High EGTs can lead to component damage and knock). Don’t let the above statements fool you about a rich condition, there is such things as too rich. It is my understanding that lamda cannot be increased past a factor of 1 (14.7 AFR) as there are other systems in the ecu that prevent you from entering a lean condition (this value can possibly be a bit higher depending on cruise control system and such upon further reading). LAMFA, in my case, has an axis starting at 50% and scales all the way close to 100% but never quite reaches.  It is my understanding that this axis percentage relates to requested torque.  It is the consensus that LAMFA will only need lambda adjustment in the last few columns of the map as it is only in these high torque request areas that we will see larger boost numbers (load request) which requires us to richen up the mixture for reasons mentioned above.

The second map that I have seen most reputable tuning companies change would be KFLBTS.  This is a map intended on component protection.  I know what you’re thinking.  Isn’t LAMFA enough?  Think of KFLBTS as a metaphorical big brother to LAMFA.  If the engine is under certain conditions (such as high EGTs) the big brother KFLBTS will come to the rescue.  From reading I have noted that KFLBTS is activated not by actual EGT temperatures but through calculated EGTs that the motronic system in its infinite complexity calculates and then spits out a result.  The trigger map that is involved in activating KFLBTS is TABGBTS.  This map is a temperature threshold for calculated EGTs.  In my file it is set at 800 degrees celcius from factory.  So that means whenever the ME7 system calculates EGTs above 800 LAMFA goes to sleep and KFLBTS wakes up to deliver some further rich mixtures in an attempt to cool down the combustion chamber and lower EGTs as well as prevent knock.  I have noticed that some reputable tuners actually make KFLBTS and LAMFA values in the high rpm and high load zones nearly identical, which I could see as a problem.  It is my understanding to keep this table a little richer than LAMFA always so that it can actually do its job.  Raising the temperature threshold from 800 to 900 or higher can mitigate the time spent in the KFLBTS as well which I have also seen examples of. 

Another thing to note.  These two maps are intended for WOT afr request mainly from what I gather.  Once you have your WOT set to where you want it you can modify another map called KFKHFM which is an air mass correction scale factor.  With this map you can adjust how much air the MAF thinks it is taking in and tune your part throttle fuel trims +/- 3 generally.  The higher the values the more air the ecu thinks it is getting so it will in turn add more fuel.  If you are experiencing lean values scale this number up and if you are experiencing rich values scale this number down.  *(Please correct me if I am wrong)*

Finally, I would like to say that the tuning tables mentioned above are during open loop operation where the computer makes fueling adjustments according to pre-calculated data and information from maps.  This will usually occur during WOT (power enrichment) conditions.  The rest of the time (for the most part) the computer relies off the input from sensors such as the o2 sensors to make fueling corrections if necessary and this is called closed loop operation.

So that would be as far as I would understand the fueling system for a basic stage 1 and 2 remap.  Obviously the correct way to do anything is to take logs and watch fuel trims and make sure nothing is under or overcorrecting too hard.  Double, triple, quadruple check your hardware folks.  You could be chasing mechanical issues for days, weeks, months if you are not careful by attempting to bandaid a very easily fixable mechanical issue such as a bad sensor or fuel filter.  Take logs before you change anything and make sure nothing looks wacky when the tune is stock.  There are great, free programs that can log for you right here on the forum that you can use at any time.  I am still getting used to the logging process and I am sure I will have questions for some of the heavy hitters out there.

I am sure there is more that I could potentially be missing here.  Could someone else chime in if I have missed something Smiley

I am currently working on boost literature and hope to have a next entry soon.
« Last Edit: February 14, 2017, 08:50:42 AM by CHRISTIANDOY » Logged
CHRISTIANDOY
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« Reply #1 on: February 13, 2017, 05:15:17 PM »

Ok so we hit the ground running pretty hard with fueling.  I’m sure I have missed things that I will add to this thread later on in my learning but for now this is what it is.  So we have an internal combustion engine.  We figured out fuel but last time I checked you need fuel, air and spark to make this puppy purr.  So let’s move on to understanding air and in this case boost as we got those big snail looking things that make us go fast.

First things first we have to gather an understanding of how ME7 actually measures boost pressure because I am sure there is a lack of maps in your file that have anything to do with PSI as you would normally see on a gauge.  There are very few maps that even convert to mbar, so now you’re scratching your head saying well then what the hell do they use to measure boost pressure and how do they limit it?  The ME7 computer is… a freaking computer, it’s capable of more calculations per second than you or I or even a group of 200 could complete in an hour.  It uses a term called “load” to calculate, control and cap boost pressure.  In the ME7 system boost roughly equates to load.

In an edit by gman86 he has described to us in more detail what the load % that we are seeing in our maps actually are.  "The one key correction that should be made is that load isn't boost. It's cylinder filling. When requesting a cylinder filling value above what can be achieved by the engines own VE (volumetric efficiency), the ECU will use the turbocharger to assist. Load can result in varying boost pressure depending on various temperatures and external pressures. Therefore it's not safe to assume that x% load will always result in y% boost pressure." What I have gathered from this edit is that depending where you are in the world the values in your load tables can change dramatically.  Depending on the atmospheric pressure where you live and the temperatures in which your car normally operates under. You should take these considerations into account when adjusting your load maps and not borrow from someone's file half way around the world.  Small changes and logs are one of the key points I am trying to get across.

Let’s take the first map that I would like to discuss LDRXN.  LDRXN is loosely described as the maximum allowable load.  People use this map as the main request map for boost which is dependent on rpm.  The table’s values are displayed in load percentage.  This is maximum permissible load the ECU will allow.  There is another map that looks very similar called LDRXNZK.  This map is the same as above except only applicable under the condition of a continuous knock.  It will pull load to prevent you from damaging your engine when the engine is experiencing a continuous knock.  I see some tuners copy and paste their LDRXN to the their LDXRNZK but I wouldn’t think this is the right way to do it.  I would much rather scale back the whole table back to either stock values or a lot less across the board than your maximum permissible load (LDRXN).  You have a few other maps too that are made to limit boost pressure so you don’t overboost to high hell or deviate from the requested load.  The first limiter that I came across in my reading was KFLDHBN.  This is the absolute pressure ratio which will also limit how much boost pressure the me7 system will allow you to achieve.  From what I read the way to calculate the contents of this map is to take the value and multiply by atmospheric pressure which will give you the max absolute manifold pressure. I.e if one of the numbers is 1.8 in the table and your atmospheric pressure is 1000mbar then multiply 1.8 by 1000mbar and you get your absolute manifold pressure which in this case will be 1800mbar which is 800 mbar (subtracting atmospheric (1000 mbar)) and converted to psi would be 11.6 psi roughly.   I hope this is making sense and I haven’t lost anyone. 

Now we get to the most fun part of the conversation! The elusive KFMIOP and KFMIRL maps that everyone seems to go bat shit crazy over.  In the motronic me7 system everything works in tandem with each other.  Every map is there for a reason and interventions occur to protect you… well mainly your engine.  I’m sure we have all heard the term torque intervention at one point in our readings.  There is two levels to torque intervention (that I know of!) the second being the worse of the two as I have heard it is something you don’t want to happen.  Now from what I have gathered torque intervention is something that happens from time to time (level 1 at least) but you can prevent yourself from hitting these interventions too often by taking your time making small changes to KFMIRL and KFMIOP and understanding that when you change one you should also change the other as they, like many maps, work in tandem with each other. 
 
This is a post by Phila_dot  is worth mentioning here. “(KFM)IRL has NOTHING to do with IOP.  KFMIRL takes an input and converts it to desired load.  That’s it.  You are good as long as the torque value at the current load and RPM is below the max allowed for the current pedal position.  There is absolutely no need to touch anything near the idle areas”.  Do not misunderstand what he is saying here as you still do need to make changes in IOP when you make changes in KFMIRL. 

I will not get into detail about the modifications of KFMIRL and KFMIOP because I am still experimenting with these maps and don’t want to spread misinformation.  I am sure there is more than one way to skin the cat.  Remember the less you have to change the better.  Don’t change more than you have to! There are also calculators such as ME7 wizard that serve to calculate theoretical KFMIRL and KFMIOP maps for you as well so check those out!

This is a response just recently from nyet!

"Basically, the only question is if "actual" torque is under safe limits, not if it doesn't exceed requested torque."

That said, if you "Make sure that the increased resulting load (when fed into IOP) does not result in torque higher than the torque that generate that load in IRL.", you should never see torque intervention.

Thanks for the input Nyet! It is much appreciated.

Another map we can take a peak at would be KFTARX which definition is “Intake Air Temp Correction Factor for Specified Load without Knock”.  This definition will aid you in understanding its function.  A lot of the time I see tuners set this table to all 1’s which effectively disables the correction from occurring at any intake air temperature.  This is how I see the majority of tune files and was a recommendation by TTQS at one point in time.  There is also a similar map called KFTARXZK which nearly the same thing just taking into consideration there is a continuous knock occurring.  I’m sure some of you have mustered together that the ZK generally is a map name tag for instances with continuous knock (or so I believe). There is a third map I have noticed in my file similarly named KFTARXB which I imagine is just another set of correction factors dependent on a certain condition but I have yet to investigate that map further.  In any event many tuners set every single one of these to 1 across the board.
Further, we have LDPBN which seems to be absolute maximum pressure limitation when motor temp is too high.  In my file all these values are set to 2550 which is the maximum boost pressure the me7 can read and control from what I have further read. 

There are further maps (other than KFLDHBN) that I have noticed so far that have to do with overboost protection.  The first being LDORXN which is the maximum permissible load during an overboost event.  This map is activated by another called TLDOBAN which is the activation timer for an overboost condition.   You also have a third map, KFDLULS.  KFDLULS is the maximum deviation of boost pressure for overboost protection enabling.  In laymen’s terms this means this is the maximum allowable difference between requested pressure (measured in mbar) and actual pressure. This map, according to the s4wiki, should not have to be touched if you set up your boost/load maps properly (I can 100% agree with this statement). If you have to max this table out you will most likely be purchasing a new turbo or engine in the near future. I imagine if the boost pressure deviates past the value in this map it will trigger a limp mode protecting your turbo as well as protecting your engine from losing its cylinder head.

So to recap we have KFMIRL, KFMIOP, LDXRN, LDORXN, LDXRNZK, KFLDHBN, KFTARX, KFTARXB, KFTARXZK, LDPBN,TLDOBAN, and KFDLULS so far for load request, control and caps.  There are a few other maps (mostly timers/time until intervention of overboost) that I have seen other tuners tweak to prevent the ecu from triggering an overboost condition.  I will not include these maps because I think this is the wrong way to do things and don’t want to spread bad information.  If someone agrees with increasing activation time of an overboost condition please feel free to share why, I am curious on this point.

As always please someone correct me if I am wrong on any of these points.  I am very new to my understanding of ME7 and would love to be torn to shreds so I can build myself up all over again!
« Last Edit: February 14, 2017, 08:25:51 AM by CHRISTIANDOY » Logged
nyet
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« Reply #2 on: February 13, 2017, 05:18:28 PM »


Directly from nyet on IRL:
“Basically the torque->load mapping from IRL should (more less) result in a lower torque if you feed that load into IOP for load->torque.
so
1) the driver requests a torque via pedal
2) requested torque is converted in to a requested load via IRL
3) ME does its thing, opens the throttle plate, picks a timing, attains a boost level. The motor responds accordingly and the ECU calculates the resulting actual load using MAF readings, etc.
4) now the actual load goes into IOP and gets converted to actual torque
Torque monitoring now needs to make sure the resulting actual torque does not exceed the requested torque.
So you don't really need to log, you can guess at the required IOP values by looking at the areas of IRL that you increased. Make sure that the increased resulting load (when fed into IOP) does not result in torque higher than the torque that generate that load in IRL.”

This isn't quite right, and I've been meaning to rewrite the IOP section in the wiki to be a bit more readable.

This is more accurate:

Quote
Another post by Phila_dot  is worth mentioning here. “(KFM)IRL has NOTHING to do with IOP.  KFMIRL takes an input and converts it to desired load.  That’s it.  You are good as long as the torque value at the current load and RPM is below the max allowed for the current pedal position.  There is absolutely no need to touch anything near the idle areas”.  Do not misunderstand what he is saying here as you still do need to make changes in IOP when you make changes in KFMIRL.  

Basically, the only question is if "actual" torque is under safe limits, not if it doesn't exceed requested torque.

That said, if you "Make sure that the increased resulting load (when fed into IOP) does not result in torque higher than the torque that generate that load in IRL.", you should never see torque intervention.
« Last Edit: February 13, 2017, 05:55:13 PM by nyet » Logged

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« Reply #3 on: February 13, 2017, 05:22:22 PM »

BTW thanks for your attempt to summarize things.. there are a few other things I could nit pick on, but in general, you have the right idea...

I'm certain prj, though, might be very upset at some of those things, so just a heads up... if he shows up, don't take it too personally.
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Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
CHRISTIANDOY
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« Reply #4 on: February 13, 2017, 05:34:04 PM »

BTW thanks for your attempt to summarize things.. there are a few other things I could nit pick on, but in general, you have the right idea...

I'm certain prj, though, might be very upset at some of those things, so just a heads up... if he shows up, don't take it too personally.

Nyet,

It's great to hear some words from you! I don't mind people being critical at all that is how I learn best.  I have definitely got a feel for all of your personalities by reading through many years of your posts so I am ready for any harshness haha!  My main goal is learning and if I get ripped to shreds in the process I have no issue with that.  I will still continue to post as my understanding gets better and willing to help the community just as you guys have all helped me so far.

Edit* Also, for the love of god please nit pick! I want to hear what I have to correct!
« Last Edit: February 13, 2017, 05:36:02 PM by CHRISTIANDOY » Logged
CHRISTIANDOY
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« Reply #5 on: February 13, 2017, 05:51:46 PM »

This isn't quite right, and I've been meaning to rewrite the IOP section in the wiki to be a bit more readable.

This is more accurate:

Basically, the only question is if "actual" torque is under safe limits, not if it doesn't exceed actual torque.

Did you mean to say requested torque for the underlined text? Sorry just want to get a good understanding of your responses.
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« Reply #6 on: February 13, 2017, 05:54:45 PM »

err yea my bad. edited accordingly.
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CHRISTIANDOY
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« Reply #7 on: February 13, 2017, 06:01:30 PM »

ok great  Cheesy
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« Reply #8 on: February 13, 2017, 06:04:00 PM »

Edit* Also, for the love of god please nit pick! I want to hear what I have to correct!

Okey. Will do time permitting. Hopefully later today or tomorrow...
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« Reply #9 on: February 13, 2017, 06:21:14 PM »

Okey. Will do time permitting. Hopefully later today or tomorrow...

I eagerly await! Thanks nyet Smiley
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gman86
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« Reply #10 on: February 14, 2017, 05:19:32 AM »

The one key correction that should be made is that load isn't boost. It's cylinder filling. When requesting a cylinder filling value above what can be achieved by the engines own VE, the ECU will use the turbocharger to assist. Load can result in varying boost pressure depending on various temperatures and external pressures. Therefore it's not safe to assume that x% load will always result in y% boost pressure.
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CHRISTIANDOY
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« Reply #11 on: February 14, 2017, 07:59:52 AM »

The one key correction that should be made is that load isn't boost. It's cylinder filling. When requesting a cylinder filling value above what can be achieved by the engines own VE, the ECU will use the turbocharger to assist. Load can result in varying boost pressure depending on various temperatures and external pressures. Therefore it's not safe to assume that x% load will always result in y% boost pressure.

I will integrate this understanding into the texts above!  Thank you very much for your input gman Smiley
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eliotroyano
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« Reply #12 on: February 17, 2017, 11:11:49 AM »

Nice summary  Smiley Smiley Smiley
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CHRISTIANDOY
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« Reply #13 on: February 18, 2017, 07:11:11 PM »

Thank you! I have been busy logging some of my first tests on 1.8t cars and vr6 cars so I have had no time to expand.  Please, if you see any issues with what I have written let me know and I will be happy to correct Smiley
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CHRISTIANDOY
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« Reply #14 on: April 04, 2017, 12:37:42 PM »

So I would just like to share an experience that I just had with a friends car.  Installed Late Audi TT/S3 386cc injectors on his 1.8T AWP engine, set the KRKTE and TVUB in line with what the appropriate numbers were (information came off the exact ecu from the audi tt we pulled the injectors off).  Fitted a larger VR6 maf and was having a hell of time with leaning out.  No matter what LAMFA and KFLBTS was designated for fueling the AFR would stay above 1 and get into dangerous territory for high RPM and high boost zones.  Anyways, had it tracked down to the change in the MAF as it is a larger ID than the stock AWP.  Did some logs, and dialed in the car as best I could for the limited time we had but ended up solving the fueling issue through the re-scaling of MLHFM table.  Later on that night I came across the mafadjust exe on here so I will be giving those values a whirl next time I am with the car.  If anyone is wondering why re-scaling of the MAF is important after upgrading to a larger one... EDIT from nyet

Sensors have velocity metering limits.

Velocity * cross sectional area gives you volumetric flow.

The sensor measures velocity (more or less).

Change the cross section, and the actual flow is different for a given velocity.

The sensor needs to be rescaled so it can account for the velocity of the air moving past the maf.  I'm sure this is all old news to some but to others that are learning I thought this would help Smiley
« Last Edit: April 05, 2017, 06:55:33 PM by CHRISTIANDOY » Logged
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