The Project Pad

Hey Guys,

I just updated to 1.2.9 and am looking at the boost PID settings and trying to get them to work. I'm looking for a good starting point with low boost and then going from there. Listed below is what I have changed, but the car appears to only be running on spring pressure ~12psi. I need a bit of help with the refDC table. I'm assuming that I have to change the y-axis values to something but don't know where to start. This is on an Audi AAN engine using the stock N75 valve and the stock Audi wastegate.

In Boost Control PID settings:
-Reducing boost refDC over MAT/EGT limits=>enable
-Gear or Speed dependent=>no dependent
-Boost valve off below=>80kpa
-Apply ma DC until=>disabled
-PD control(far)=>-20kpa
-PD control(close)=>-16
-PID overlap=>6kpa
-Boost P=>35
-Boost I=>60
-Boost D=>20
-Boostcontrol PID integral limit=>100
-Boost target=>MAP target
-Reference lookup=>Boost target based
-Boost PWM max value=>100
-Boost PWM min value=>0

When the Reference lookup is set to RPM/gear/speed based(basically the old boost control) the car boosts fine and sees ~21psi.

Thanks for any info you gots!

I use the apply max DC set to a point less than the PD to minimize overshoot. I am also running very little D and minimal I.

Regarding the table, I am not sure what the Y axis is supposed to be but I have all cells at 100.

As you know, it is difficult to compare exact PID numbers. I'd love sombody who know what they are doing with the new PID setup to chime in.

I've read over this but, IMO, it needs updating http://www.vems.hu/wiki/index.php?page= ... dReference

I read that too, Ed. It carries on in the fine tradition of vems knowledge vs. documentation. Lol. I'll apply what you posted and see what that does. I sent zeet a pm asking some ?'s as it sounds like he's got a pretty good handle on it. Or at least it sounds like he does...

I should say that I am nailing my 200kpa target but I wonder if I am leaving spool on the table; some of that must be from running the base ignition tune and erring on the side of richness.

More slivers of info

http://195.159.109.134/vemsuk/forum/ind ... l#msg20393

My refDC Table vs Boost target has "1020" for every Y value; not sure what that means.

Ok, so what I understand is that the 1020 in the Y-axis is just a peak value which turns off the control? What I have done is just put a peak boost target # in the top cell and 100kpa in the bottom and scaled it up from there. You could also put the peak boost capability of the turbo in that upper cell and scale down accordingly. I didn't do that as until this thing is on a dyno with someone who knows more about this than I, I'm not going to get close to the peak boost of the HTA3073. Anyway, then I just scaled the RPM values as I saw fit for where boost comes on, peak boost etc. to past red line. Then the cells in the table I have put in a duty cycle that I want the N75 to operate at that cell. This won't do much while spooling for peak boost, but will give you control in that individual cell if you are driving in that area(like in the twisties when you are on and off the throttle running from 4k-6krpm and back a bunch). I still need to do some tweaking with the PID values as I tried a typical 80 20 30 strategy and there was a lot of fluctuation once running at full boost. I've gone back to the 35 60 20 and it behaves well. It nails my peak boost of 225kpa every time with only a slight overboost, if any. Spool is pretty quick, and like you, if the timing was tweaked more, it would be quicker. The really nice thing about these controls is that VEMS pays attention to your peak boost numbers much better than before and spools better too.

I think once you put some proper values in the Y-axis, you'll see a noticeable difference. Well, I hope anyway!

I'll post more about this tomorrow...

I REALLY wanna try the new boost control. I think I should be able to get my car to spool right at 4k. So much to do first though, argh. Like get my ecu back lol

So, just keep figuring it out so that when I need to, you guys have done all the hard work

Thanks Ed. I haven't seen this yet.

Mcstiff wrote:http://forums.quattroworld.com/s4s6/msgs/246511.phtml

I wrote this up off the top of my head, so if you found out I missed something or made a mistake just let me know and I'll update it. Also you should let me know if you want any other writeups - so far I've done idle, and boost control, and Ed has done fuel.