NefMoto

Hey,

I stuck in unterstanding the application of LDRXN, when I compare 018Q (180PS) und 032E (225PS) of a Audi TT:

As I unterstand, LDRXN is manly limiting max load on WOT. You can do a rugh estimation of the boost pressure based on LDRXN at WOT. But when I compare LDRXN of 018Q and 032E dumps, LDRXN at 032E is lower than 018Q ?!

The estimation of LDRXN 018Q fits to the boost, I measure by log (around 1650hPa @5000rpm).
Reading in forums tells the max boost of the 032E should be around 1900hPa, but the estimation by LDRXN will give only 1550hPa @ 5000rpm..

Are there differend factors for LDRXN for differend software and my A2L is worng ?

Or what is the reason, why the load of the 032E is lower than 018Q, when torque and power is higher..

Thanks for hints and help

Difference in the VE of the engine (KFURL & KFPRG)
Timing maps are higher
Turbo flows a lot better.
And also the compression ratio is 9:1 in the 225BHP engines,
instead of the 9.5:1 in the 150/180BHP engines.

There are tons of other things that are different in the ECU load calculation between the two.

Hope it helps :)

yes, some steps forward, thanks !

Your hints are clear and known in some cases but where I still stuck:

Does the 032E realy runs with less boost than the 018Q or will LDRXN converted by other maps that at the end the boost at WOT will be higher then 018Q ?

IIRC they should boost around the same 0.8 bar :)

Ok, now I got it:

LDRXN isn´t maximum load.
It is corrected by some temperature and admosphaeric based maps, as well as overboost. So lower values in LDRXN do not meen, having lower boost..

Thanks !

No, that's exactly what it is.
Maximum specified load.
There are some other factors that can increase or reduce it like IAT (KFTARX)

LDRXN is the max load the driver can request from the engine at 100% pedal.
And KFPED is what % load is requested at the given throttle %

ok..

in this case the boost of the 032E will be lower the 019Q, if the A2L of the 032E, I use, is correct..
And the maximum boost should be around 1600hPa and not 1800hPa or 1900hPa, as you find in forum.
Please take a look at the attachemend of the 1. post.

THIS is eactly, why I struggle at the moment :(

No because the load calculation of the 2 ECUs are different.
Boost is the same, internal calculated load is different :)

Then the discription of the S4wiki is misunterstanding !?

https://s4wiki.com/wiki/Tuning

 ???

Based on this calculation, the 032E should have less boost then 018Q. This is the reason, why I struggle and ask the question :( But this estimation seems to be too rough for 032E, 019Q it fits quite well.


So, I need to convert LDRXN better on this way to get the right boost:

plsol = (rlsol + rfagr) / fupsrl / fpbrkds / vpsspls



.. I think I got now the right direction