Hi there,
I am trying to understand how to control my boost with throttle when WGDC is 0%. I have read S4Wiki and probably every post on Nefmoto covering this, but still can't get my car to run as it should.
First of all the car:
Audi TT mk2 2.0 BWA MED9.1 with K03 hybrid turbo, custom intake (MAF housing same dimensions as stock) and 3 inch custom exhaust de-cated.
My current mods:
Audi S3 BHZ KFMIRL and KFMIOP
Tweaked KFLDRL and KFLDIMX, so I just need to adjust IMX (no seperate linearisation map)- take note it is a very basic map now, it is still under my development.
And now to my problem/problems:
I found on S4Wiki section about Base boost and wastegate spring pressure.
With aftermarket and/or tighter wastegates, you may experience bucking and choppy throttle response in part throttle near waste gate cracking pressure[29]. The throttle angle desired is dependent on the boost pressure in a turbo car since after a certain angle, throttling losses are negligible and it is better to hold the throttle wide open. But if the turbo cannot be controlled at that boost pressure via waste gate control any longer (because the wastegate no longer can open at that pressure), the ECU needs to be told to continue to use the throttle (and not got WOT) up to the new, higher boost pressure to regulate torque instead
I think this is what I am looking for. What I want to do is to use my throttle to lower pressure in the intake manifold when wastegate is 0% and car is still overboosting. In my case this situation happend when cruising around 120kph (2500+ RPM, accelerator pedal 25-30%)
S4Wiki says:
To correctly determine how much throttle opening is required to produce the amount of torque requested and prevent the ECU from going WOT prematurely, a few maps have to be tweaked in the module LDRPLS to set the base boost pressure in the ECU. The maps that set base boost are:
KFVPDKSD - Target pressure ratio in dynamic operation
KFVPDKSE - Target pressure ratio in steady state operation
Here comes first problem: In all damoses for MED9.1 there is only KFVPDKSE, no KFVPDKSD. Is it true? There is only this one?
Second problem: KFVPDKSE has different vpssplg_w axis to what I've seen in ME7. Now I should add that in CWPLGU I have "1" value, which means that in my ECU vpssplg_w should be equal to requested boost (absolute pressure)/atmospheric presure.
As you see below values of my KFVPDKSE are <1, which would mean that values of vpssplg_w axis are negative boost
I suspect that in MED9 wpssplg_w axis represent something like (requested boost-atmosperic pressure)/atmospheric pressure
Assuming I am right let's move on.
On S4Wiki I've read that KFVPDKSE values below PSPVDKUG (0,95 in my case) represent areas where requested boost is below spring/cracking pressure which means that even if WGDC=0%, the wastegate reamins closed. So the row in which value exceeds 0,95 should indicate my stock spring/cracking pressure which in my case should be 0,420Bar.
Since I wanted to check if I am right, I've changed all values over 2500RPM of KFVPDKSE to 0,94. This should prevent ECU from going WOT. After that I've changed values over 2500RPM of WDKUGDN to 10%, cause I wanted to see if it will limit throttle angle to 10%. It didn't
What am I doing wrong?
Please help.
