NefMoto

In both the 551R allroad ME7.1.1, and RS4 binaries KFMLDIMX is perfectly linear. I'd like to talk about how to properly tune the PID. I've read about the "base boost pressure" maps (plgrus_w), and that DIMX is calibrated differently, but I don't quite understand HOW it works.

Thanks, as always.

(http://i.imgur.com/turxbXI.png)

it is my understanding that you want to get WGDC as close as possible to where you need it first.

After that, tune for P, then D, and then I.  

You want the PID to have to do as little as possible.

I found a webinar vid on youtube from Motec Australia. http://youtu.be/SefKQb9y_B4 (http://youtu.be/SefKQb9y_B4)  If you can sit through it (47 minutes worth of PID tuning logic), I'm sure it will help, not only does it explain how to properly tune PIDs, it explains why you should do it the way that is explained. It's very "in depth" and the guy recommends watching the first webinar on PIDs if you don't understand some of the things he talks about. Boost and idle PIDs are used as examples in addition to a few other real world scenarios, so its pretty easy to relate to what the guy explains.

I'm aware of how to tune the PID :P

But this doesn't work the same way.

I'm running the 4z7907551R me7.1.1 ecu & my process of tuning the PID was a little different then how people are tuning the S4 M-box ecus. I'm not saying that my way is the best way to do it or even the correct way, but I've had good results. It's been a while since I did this so hopefully I'm not leaving anything out here.

First thing I did was to set KFLDRL to 0 in all cells and get a 3rd gear log of my "base boost pressure" with 0% WGDC. I used that data to fill in the last column of KFVPLGU, and then adjusted the rest of the map to keep the same shape as stock but increased for my new wastegates (15-16 psi). With it set up this way, the ECU knows to control boost under the wastegate pressure with the throttle plate (no need to change the vpssplg_w axis for KFVPDKSD/E). I believe I did a little logging here and scaled the whole KFVPLGU up or down a little bit, I don't really remember anymore.

Here's my KFVPLGU. Wastegates were set to 15 psi on the bench, boost on wastegate pressure peaks around 16.7 psi and tapers to just above 15 psi by redline. I set all the rpm rows before I hit my peak boost to the same value, I'm not sure if I was correct in doing that.. but I haven't noticed any ill effects.
(http://i58.tinypic.com/2d937k8.png)

I then went and got logs at 0, 10, 20, 30, 40, 50, 60, & 70 %WGDC, and used that to make my KFLDRL map like you normally would.

Due to the KFVPLGU changes, the KFLDIMX plsolr_w axis is now essentially the difference between requested boost & my wastegate pressure (plgrus_w). After dialing it in, it tells the ecu how much duty cycle is required to make [plsolr_w] mbar over the wastegate pressure. My KFLDIMX didn't stay linear like it was stock, I think audi must have calibrated KFLDRL so that it would arrive at the right WGDC given the linear KFLDIMX output.

(http://i60.tinypic.com/v8g2s1.jpg)

(http://i59.tinypic.com/iz21xf.png)

After that point dialing in the rest of the PID was the same.

Thanks! That is a great explanation.

On the S4, the axis for KFVPLGU is pssol_w and the output is a factor for pu_w.

On the RS4, the axis for KFVPLGU is pu_w and the output is mbar. The calibration takes RPM into account here instead of in KFLDIMX.

If you match the values with the pu_w axis you end up with the same function as in the S4 files.

This is genius if it works! Will try to set base-boost on my rs4 with 16psi actuators and report back  :)

So, let me get this straight,

I would leave the DRL the way I usually tune it, but set the axis of IMX to the amount of boost I want above base pressure, GLU. For instance If I have a base boost of 1000 mBar and I want 1600, my IMX axis should be set for 700 in the last column and set that column to the duty cycle required to get that pressure above base gate pressure. I then can get the values for IMX from the logging done to create the DRL map directly with fixed duty cycles.

Will It matter if the map limit is exceeded? Or will it act like the M box and run open loop and follow my IMX values now?

Can you elaborate? In the FR, I see KFPLGUB/KFDPLGU, not KFVPLGU... and I don't have any of the three in any of my ME7.1 mappacks (including my RS4 kp).

To close the loop, we need to add the map/axis to all the defs ... :(

ETA: in my G-box kp i see KFVPLGU at 11135, but it is all ones..

Its in my 551R xdf that PRJ posted, Maybe only 7.1.1?

Like he said, it is a correction to pu_w in some files (e.g. S4 7.1)... in the g-box all ones means base boost is ambient (stock)

I'm fairly sure i'll find that they are all ones in the various non-RS4 ME7.1 variants. Time permitting i'll find it in Mbox.

KFVPLGU 0x11129 * 0.0078125

pssol_w SPS08LDUW 0x156AE * 0.0390625

nmot_w SNM08LDUW 0x12AB6 * 0.25

Thank you, as usual, phila!

Excellent, Added to my def. Thanks!

While this correlates well with my fully defined G-box, the pssol_w axis values look odd... they are 1.1719-9.3750..

that can't be pssol....

It's definitely pssol_w. The table isn't used however, similar to the lamfa axis.

Thanks!

I should clarify, the map is used, but it does nothing as it is all 1's.

For the sake or completeness, there is also KFWPLGTA which gives plgta and is also filled with 1's.

KFWPLGTA 0x19749 * 0.0078125

Rows:
nmot_w SNM08LDUW 0x12AB6 * 0.25

Cols:
tans STA08LDUB 0x1010C * 0.75 - 48

The output from KFVPLGU is multiplied by plgta and the result is then multiplied by pu_w giving plgrus_w.

Therefore, plgrus_w is always equal to pu_w.

I'm late to the party per usual, but this thread is a big help.  I never even realized until recently that the allroad boost was controlled this way.  Thanks to everyone!

I have problem defining rpm axis for KFVPLGU.
Would any of you take a look,  what is the RPM adress, please??

0x12D72

16 bit, .25*x

Perfect, thanx DD

I had found KFVPLGU on F-box @0x15946 but can not find on k-box...

1E2F0 in K box   8x16

thanks again  ;D