New boost control XDF tables

carabuser

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Oct 2, 2019
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I've been using a few new tables in my custom tune that aren't currently out in the wild so I thought I'd post the new XDF tables along with the throttle correction and burble tables previously defined. There's also some misc tables I put in for ROM revision and VIN number that are in my personal XDF that I find useful.

I think at some point these will make it into the public XDF but for people using custom tunes, especially ones with DCT cars, these 2 new boost control tables should be very useful.

Both the tables act as divisors on the final calculated boost target. If the ECU load calculation ends up with a target boost pressure of 15PSI and you have a value of 1.1 in the cell for that RPM and pressure ratio then the actual boost target will be 13.6PSI. If however the ECU load calc outputs a target of 15PSI and you have 0.75 in the cell then your target boost will be 20PSI.

As you can see from the stock values from a DCT car, if my boost ceiling is intact at 18.56PSI, no matter what load I target the boost target will only ever get to 17.8PSI, which is a common complaint for DCT users. If I adjust the divisor to 1.0 then my car will target the full 18.56PSI.

This does not get around the boost ceiling problem for DCT users though, just allows us to target slightly more boost. The main benefit of these tables is that you can smooth out the boost target and get rid of that annoying dip that most tunes have on the onset of boost as shown in the image below of an RFP tune:
Capture.PNG


Be careful when lowering values in the table as if your boost overshoots and you hit the boost ceiling you will get throttle closures. I tried running it at 1.0 for a while and any time the boost even slightly creeps over the ceiling you get horrible throttle closures. For manual and AT users who have a raised boost ceiling then this doesn't matter.

There's two different boost pressure target modifier tables in the logic so I defined both. The Normal Operation is the one that seems to be active most of the time, I'm not certain when the Dynamic Operation table is used as the logic isn't clear but I suspect it's related to spool mode.

I've only defined these in INA0S. If anyone wants to port them for other ROM revisions then feel free to upload them.

Capture.PNG
 

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  • INA0S (New Tables).xdf
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RSL

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Aug 11, 2017
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Does boost actually move with it? I vaguely remember there being a separate factor or something that was the basis of what the turbos actually responded to. I may be misremembering, but swear target line and target used for control were actually separate entities (though tuned to be similar stock).

Drop a stock bin in, drop the divisors and see if actual boost is anywhere near the raised target to confirm.
 

carabuser

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Oct 2, 2019
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Does boost actually move with it? I vaguely remember there being a separate factor or something that was the basis of what the turbos actually responded to. I may be misremembering, but swear target line and target used for control were actually separate entities (though tuned to be similar stock).

Drop a stock bin in, drop the divisors and see if actual boost is anywhere near the raised target to confirm.

You would need a WGDC increase to meet the new target like any other increase in boost target. The PID will try and reach the new target but in standard form won't have enough movement.
 

RSL

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You would need a WGDC increase to meet the new target like any other increase in boost target. The PID will try and reach the new target but in standard form won't have enough movement.
Right, I need to see if I can find the bin I tested with to see if PID was limited or not. I just remember base tune was close to stock boost levels, divisors jacked the target up to 19-20psi, but I don't remember actual going up. I'll try to confirm when I get home tonight.

There's definitely another variable/factor related to control/setpoint, but can't remember exactly what it was. I thought it was WGs, but might have been IM. I try to take notes when testing tables, but not my strong point and finding them later is always iffy lol
 

carabuser

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I just re-read through the program documentation and in the context of these two tables, dynamic is a combination of overboost being active or another factor which I can't work out the function of. Both the Normal and Dynamic tables are put into a blending function block that means both tables are probably interpolated. So the take home from that would be just to set both tables the same.

I've attached the logic relating to these tables. For reference Pssol refers to the target intake manifold pressure which is the result of many pages of logic which calculate the target intake manifold pressure based on the target load and about 20 other factors relating to efficiency models and correction factors, Pu is the current ambient pressure and Pld_soll is the boost target that we see in our logs.
KF_PSPLD_DYN and KF_PSPLD_ECO are our new tables.
 

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  • 943.pdf
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RSL

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You would need a WGDC increase to meet the new target like any other increase in boost target. The PID will try and reach the new target but in standard form won't have enough movement.
Might've been PID, ceiling was set to 15%. Snapped up and right back down nowhere near target, but might've been a P issue for the larger than normal error size on that bin. Either way, too long ago to remember exactly what other target/factor/set point I think was in play and don't have any notes on it.

divisor.png


I tested the fixed target at the time too, which by-passes all the correction factors, offsets, filters, etc. Not that I'd run it permanently, but I expected a 30FF at PT and never got one. I wonder if setting that switch also disables diagnostics.

fixed_target.png
 
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DesertDude

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Jul 16, 2017
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Interesting that my 335IS INAOS ROM has lower default values than your Z4 in the higher RPM range for the (Normal Operation) map. The RPM values are mapped differently in the 4th and 5th columns as well. Dynamic seem to be the same, however.

1581555862935.png
 

carabuser

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Interesting that my 335IS INAOS ROM has lower default values than your Z4 in the higher RPM range for the (Normal Operation) map. The RPM values are mapped differently in the 4th and 5th columns as well. Dynamic seem to be the same, however.

View attachment 35081
I did notice that the values in other INA0S ROMs were different. The ones from the JB4 backend bins were lower too so assumed it was something to do with Manual vs DCT but it could as easily be a US vs EU difference.

Is your 335is manual or DCT?
 

JohnDaviz

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I tested the fixed target at the time too, which by-passes all the correction factors, offsets, filters, etc. Not that I'd run it permanently, but I expected a 30FF at PT and never got one. I wonder if setting that switch also disables diagnostics.

View attachment 35071

Can you educate me on the tables to get to that fixed target? I probably would not disable all but would be interesting to know which there are :)
 

RSL

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Can you educate me on the tables to get to that fixed target? I probably would not disable all but would be interesting to know which there are :)
Added to @carabuser 's INA0S xdf from above for consolidation and attached here. Enable switch (1) and set target. I tested with some city driving and didn't have any 30Fx at PT with it, but YMMV depending on other tune params. I also only tried with around 12psi target set, nothing crazy. Use some caution with setting if you have a scaled map.

mbc.png


Ported the Boost Control Stuff for IJE0S
The rest is out there somewhere already

stock values from my personal MT EU rom for comparison
View attachment 35112

That IJE0S has a choke hold, didn't realize any roms stepped on it that hard. To round out the compares...

335is INA0S stock:
335is_INA0S.png


US 1M Stock:
US_IKM0S.png
 

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  • INA0S (New Tables).xdf
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JohnDaviz

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Interesting. I just opened my IJE0S Map and i have the INA0S values in it.
 

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  • Boost Control IJE0S.jpg
    Boost Control IJE0S.jpg
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all4bspinnin

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Jun 12, 2017
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Whats interesting about this is the 1M's did always spool much faster than other ROM's. This is probably one of the reasons. I need to look at it further

Edit, i pulled an IKM0S ROM and took a look at it. Definitely different.

Edit 2: I just realized RSL posted the picture of the 1m ROM already. Sorry for the double pic

Also, on a side note... be careful using these 1m values. The car will make 19+psi extremely quickly at lower RPM. You may run into a situation where the car will see knock due to the rapid onset of boost at really low rpm.
 

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  • 1M boostcontrol.PNG
    1M boostcontrol.PNG
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  • 1mboostcontrol2.png
    1mboostcontrol2.png
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