A quick and easy way to street tune your CSL conversion for drivability.

[karter16]

I am not using one. I am under the impression that relative opening is a mixture of ICV/TPS/MAP and is directly tied to the load table. This definitely corrects the whole table as I would otherwise have a run-away condition if my cells weren’t in the right places. I’ve asked many moons ago on this forum if aq_rel is load and was told it was, what is your reasoning for the question?

For what it's worth I've just been working through this in my disassembly project and thought it would be worth noting here. Below is a summary of how it comes together:

AQ_ABS (absolute cross-sectional opening) = AQ_ABS_LLS (absolute cross-sectional opening of idle control valve) + AQ_ABS_WDK (absolute cross-sectional opening of throttle plates)

AQ_REL (relative cross-sectional opening (%)) = (AQ_ABS - K_AQ_ABS_MIN (minimum possible cross-sectional opening)) / (K_QA_ABS_MAX (maximum possible cross-sectional opening) - K_AQ_ABS_MIN)

This AQ_REL value is what's used in the standard M3 software, a commonly referenced example of this is the VANOS maps - AQ_REL is the y-axis in those tables.


The important thing to know is that AQ_REL isn't used directly in the CSL AlphaN maps. It's actually a modified version of AQ_REL that is used.

For the purposes of this explanation I will call this modified value AQ_REL_ALPHA_N it is calculated thusly:

AQ_REL_ALPHA_N = AQ_REL / AQ_REL_ALPHA_N_FAKT

So what's AQ_REL_ALPHA_N_FAKT? It's just my name for the output of the lookup curve at: 0xE056




x axis is N (rpm) and the output is a scaling factor.

Essentially what this means is that AQ_REL_ALPHA_N will be a smaller value (between 0-30% smaller dependent on RPM) than actual AQ_REL beneath 2400 RPM.

Additionally there is another value that is also calculated in the same routine, let's call it AQ_REL_ALPHA_N_PT_KORR which is additionally scaled based on P_UMG (Ambient air pressure) and TAN (Intake air temperature).



This value isn't used in the CSL AlphaN maps (or in other operational code), but it is used in two routines which seem to be involved in the sending/export of data (I haven't figured out yet if these are the DS2 routines or something else). Crucially AQ_REL_ALPHA_N is NOT referenced in any sending/export routines. Which raises the possibility that the "Relative Opening" datapoint that we are logging in TestO isn't even the same data point that is actually used as an input to the VE table (indeed it could even be the standard AQ_REL variable). Looking at the two tables above they are normalized around 20 degrees C intake temp and ambient air pressure of 962mbar, so it's not going to be too far off either way, but for example today in Auckland was 1016mbar at 20C, so PRESUMING THIS IS THE CASE I'd be looking at a 4% variance.

I will spend more time looking at this to see if I can establish with certainty which of the two variables "Relative Opening" represents.


Also worth mentioning that the MAP sensor does not have any part in the calculation of AQ_REL. The MAP sensor is used in the calculation of air mass, which in turn is used in the calculation of final Relative Fill (an adjustment to the value obtained from the VE table).


I realize this post is more focused on the "academic" side but hopefully of use to the collective understanding.

[ac427]

Filtering the log and compiling the logged data into the required table.

Thanks, Are there any suitable alternatives to MegeLogViewer HD ?

Would https://datazap.me/ do ok or is MLVHD worth the $50 ?

[bmwfnatic]

Sorry for another thicko question.

If TestO is used to log the data and then Excel or MathLab is used view and to manipulate the data.

What purpose does MegaLogViewerHD serve?

Filtering the log and compiling the logged data into the required table.

[ac427]

Sorry for another thicko question.

If TestO is used to log the data and then Excel or MathLab is used view and to manipulate the data.

What purpose does MegaLogViewerHD serve?

[ac427]

I have Testo running ok but how and what do i need to log?

[YulCmr]

The WOT table is a multiplier applied over certain cells in the VE table. So changing your VE table can affect your WOT map. The correct way to tune WOT is actually to tune the VE table, but as you state, the car runs open loop in these sections so this method should achieve the same outcome. No, this method will not change your WOT tuning and AFRs.

Thank you for your answer.

After a quick reading of the tune, full load table was indeed modified, but so was the big Alpha N table. (now richer on bottom end and leaner on top end).

If I get corrections in my VE table using this method, can it "fine tune" the tune I got ?

From my understanding, as my VE table keeps dropping after 3 passes, it means that I was running a bit rich with this tune ?



As far as I can tell, drivability has been GREATLY improved after 3 passes !

Thank you guys.

[Bry5on]

The WOT table is a multiplier applied over certain cells in the VE table. So changing your VE table can affect your WOT map. The correct way to tune WOT is actually to tune the VE table, but as you state, the car runs open loop in these sections so this method should achieve the same outcome. No, this method will not change your WOT tuning and AFRs.

[YulCmr]

Hi !

I'm currently in the process of logging and correcting the VE map. (3rd iteration as of now, slowly getting there)
Can someone confirm (or correct me) that, VE Table is only used during Closed loop ?

I'm doing this process over a WOT corrected tune, so I just want to be sure that during WOT, ECU does not use VE table. (Which would interfere with the current WOT tune)

Thank you for your work guys, this is quite easy to understand and replicate (even for a noob like me)

[inlinesix123]

Just finished this. The car is changed, shifts fight the engine a lot less, downshifts are smoother. 10/10
Thanks to Suleiman Pasha.

[Bry5on]

Bry5on and heinzboehmer (hope you don't mind me tagging you both!) you've driven each other's cars post this tuning process yeah? Keen to know what differences there are in "drivability" between flap and no-flap setups that are properly tuned? Any thoughts/comments on that?

No difference that I can tell, really just the noise. I like having quiet mode available - I drive probably 60/40 in sport (loud) mode where the flap opens at 3300rpm or 40mph.

[heinzboehmer]

Bry5on and heinzboehmer (hope you don't mind me tagging you both!) you've driven each other's cars post this tuning process yeah? Keen to know what differences there are in "drivability" between flap and no-flap setups that are properly tuned? Any thoughts/comments on that?

I bet Bryson will tell you his flap makes a difference in driveability cause he drives his car a lot more than me.

However, I haven't noticed enough of a difference to make me want to get the flap.

(Also Bryson's car has smaller diameter tires, which, to me, makes a much bigger difference in driveability)

[karter16]

Bry5on and heinzboehmer (hope you don't mind me tagging you both!) you've driven each other's cars post this tuning process yeah? Keen to know what differences there are in "drivability" between flap and no-flap setups that are properly tuned? Any thoughts/comments on that?

[SliM3]

Logic would dictate that setting the flap to 10k would run the engine lean at part throttle as the part throttle fueling maps don't seem to get touched by tuners. If you don't have a tune then this is even easier. Personally I'd rather stay on the safe side and target stoich like the factory did, or even a little rich, at higher loads (which is where the flap map has an effect).

If you want to make life harder for yourself, you can zero the flap map then apply more fuel in the main map in the same places. This would have the same effect.

A leaner burn at high loads will tend to run hotter with no power gain. No reason to run lean in that part of the map IMO.

More than one way to skin a cat when it comes to this stuff, for sure. I tend to target the map that directly controls the specific function because a lot of these parameters interact with one another and a change in one spot can have an inadvertent change somewhere else.


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[Bry5on]

Logic would dictate that setting the flap to 10k would run the engine lean at part throttle as the part throttle fueling maps don’t seem to get touched by tuners. If you don’t have a tune then this is even easier. Personally I’d rather stay on the safe side and target stoich like the factory did, or even a little rich, at higher loads (which is where the flap map has an effect).

If you want to make life harder for yourself, you can zero the flap map then apply more fuel in the main map in the same places. This would have the same effect.

A leaner burn at high loads will tend to run hotter with no power gain. No reason to run lean in that part of the map IMO.

[Slideways]

Set to 10K. This will force the DME to operate as if the flap is closed and will only use the main VE map, as opposed to running the flap as "full open" which factors in the supplemental map.

Will that limit power from 3.3k to 8k? All the CSL modified tunes typically have the default flap settings, which makes me think that they are tuned like this. Guessing that the tuners are changing the main VE map and leaving the flap supplemental map alone.