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Author Topic: Boost PID tuning for noob  (Read 55380 times)
Dave9n3
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« on: November 11, 2016, 04:19:25 PM »

So started my tune not so long ago and feel like its going OK so far. Now I've increased my boost significantly it looks like my car is over-correcting when I peak, to the point where it dips under requested, comes back up again and overshoots. I've done a bit of reading and tried to make sure I'm logging the correct variables to help solve this.

spec is:

k03s 1.8t
2.5" cooler pipework and fmic
4bar fpr 317cc injectors
2.5" exhaust system no cats
intake pipe etc etc

From the wiki i can see that it says if ldimxa adaptions are happening (there are some) I will probably need to look at changing KFLDIMX and LDIATA. I'm thinking that the PID being stock is the reason for spec boost not meeting requested though I could do with some more expert opinions  Wink

I'm hoping its not related to KFMIOP or KFMIRL being tuned incorrectly. From the variables I am able to log i can see that mifa_w, misol_w, migs_w and miist_w aren't exceeding miszul_w and i have no crazy timing oscillations that would make me suspect its the torque model causing the problem though i may well be wrong.

Hoping I can get some advice on this to move me forward. Another problem i have is that i cant seem to line up/define KFLDIMX correctly in my file (032TL ecu) when comparing to a 032HN the hPa axis doesnt come out right as pictured, can anyone offer advice on finding this or even possibly help me find it as I think even if this isn't my problem at the moment it'll need looking at soon. In the meantime i shall continue to study the wiki and probably get on youtube to watch some videos on PID control.

thanks in advance,

Dave


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armageddon
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« Reply #1 on: November 11, 2016, 04:30:35 PM »

I would start to make boost request more "stable" at 3000-4000rpm and reduce imx a little at that rpm range
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Dave9n3
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« Reply #2 on: November 11, 2016, 04:39:22 PM »

Thanks for the reply, I've attached a picture of LDRXN as it is in my file, around 3500-4000rpm requested boost seems to take a dip but I'm not sure why since my LDRXN doesnt look like it would have a dip at that point. At this moment I'm unable to properly define KFLDIMX  Sad though I've defined LDIATA
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IamwhoIam
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« Reply #3 on: November 12, 2016, 08:16:02 AM »

At this moment I'm unable to properly define KFLDIMX  Sad though I've defined LDIATA

So you were able to copy-paste KFLDRL but not KFLDIMX? You should spend A LOT more time on learning how to find the maps by yourself before you start trying to "tune" the car without even having properly-defined maps for it.
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I have no logs because I have a boost gauge (makes things easier)
Dave9n3
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« Reply #4 on: November 12, 2016, 08:55:29 AM »

When you say copy and paste how do you mean? I've been defining maps the only way i know how to which is to compare windows in winols, then when i find a match I transfer the map structure. As I've moved along I realised I need more maps so have kind of been adding them as i go along. I'm not sure why i was able to find KFLDRL but am struggling to properly find KFLDIMX, Is there a better way i can learn for finding maps? The axis data just doesn't look right at all lol

The .kp file i uploaded is all my work, albeit the file could be better i have defined a fair amount already. I have been unable to find a damos for my ECU. I really would appreciate some advice on how to find the maps correctly, as at the moment I'm a bit stuck lol
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dv-008
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« Reply #5 on: November 13, 2016, 06:23:14 AM »

KFLDIMX:

0x1EA4E 16bit, factor: 0.005 * X

ROW: 0x15D42 16bit, 8 rows, unit hPa, factor: 0.039063 * X
COLUMNS: 0x1303A 16bit, 16 columns, unit RPMs, factor: 0.25 * X

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Dave9n3
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« Reply #6 on: November 13, 2016, 09:11:51 AM »

Thank you very much! my axis now looks correct  Grin may I ask how you managed to find that? I'd like to learn how to find them rather than just having to do it by comparing.

Thanks again, that was a big help to me.
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dv-008
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« Reply #7 on: November 13, 2016, 10:57:48 AM »

Hello Dave,
Reverses the axes, so it will look better

It has taken me many hours to find the maps, comparing with the 032HN and 018CB defined files

Since for our cars Ibiza 6L FR 1.8T (032QN), Ibiza cupra 6L 1.8T (032RP) & Polo gti 9N3 1.8T (032TL) there is very little information and the definitions are almost the same between them
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Dave9n3
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« Reply #8 on: November 13, 2016, 11:10:47 AM »

Will do, i just did that so i could squeeze it on the screen!  Grin

Yeah there is little info on these ECU's. I had found all the maps I needed just by comparing up until now. Maybe i should have just used a HN or HJ file as i think they may be able to be cross-flashed and there are some good damos around for those lol.

Have you successfully tuned KFLDIMX for your car?

I'm going to do a lot of reading and then try to sort out my boost pressure overshoot.


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dv-008
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« Reply #9 on: November 13, 2016, 01:27:21 PM »

First raise the limits in KFDLULS

To start tuning KFLDIMX,
Set the last row (980 hPa) all to 95
Add +4 or +5 offset to rows (750 & 900hPa) in range 2250-5500rpm
and tune KFLDRL & others...
« Last Edit: November 13, 2016, 01:30:05 PM by davidgs » Logged
Dave9n3
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« Reply #10 on: November 14, 2016, 01:08:17 PM »

Thanks! I think i have been getting a little confused and concentrating too much on KFLDIMX.

Should I make changes to KFDLULS since as the moment I have not had any throttle cut from boost deviation? I think standard values are 400mBar and from my logs the max deviation i can see is around 100mBar.

I'm a bit confused as to why we make changes to KFLDIMX so i need to do more reading on that.  Huh Huh

As for KFLDRL, as an example is this the map i would use to correct the overshoot, since the result of the PID goes to KFLDRL and then dictates the n75 duty cycle - would I find the part in KFLDRL that lines up with the rpm range where i see the overshoot and slightly reduce the duty cycle to cure it. Is this the correct way to tune it?

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nyet
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« Reply #11 on: November 14, 2016, 01:10:44 PM »

don't touch KFDLULS

As for KFLDRL, as an example is this the map i would use to correct the overshoot, since the result of the PID goes to KFLDRL and then dictates the n75 duty cycle - would I find the part in KFLDRL that lines up with the rpm range where i see the overshoot and slightly reduce the duty cycle to cure it. Is this the correct way to tune it?

No.
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Dave9n3
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« Reply #12 on: November 14, 2016, 03:38:11 PM »

My bad - Thanks for clearing that up though.

KFDLULS wont get touched, I'm not getting any pos or neg deviations (yet) - and if i was then increasing these limits wouldnt be the answer to those problems right?  Tongue

Looking at my I adaptions I can see there is some, from your wiki it states if they're downwards then I'm overboosting. I'm now just not sure what this info means in terms of making changes to KFLDIMX and LDIATA
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nyet
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« Reply #13 on: November 14, 2016, 03:42:35 PM »

increasing these limits wouldnt be the answer to those problems right?

correct!

Quote
I'm now just not sure what this info means in terms of making changes to KFLDIMX and LDIATA

You should probably review how a PID works, and the relation between over shoot, under shoot, and PID integrator wind up.

I don't have the patience right now to give a lesson on PIDs Sad
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
Dave9n3
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« Reply #14 on: November 14, 2016, 03:51:55 PM »

No doubt, it seems like a big subject and a complicated one to cover easily. I think youtube may be my go to place for a half decent noob explanation to try and fully understand what is happening with my boost control.

Slowly but surely moving forward with this so thanks for pointing me in the right direction. It makes it a whole load easier when you at least know what not to do - and also what I need to know/go read up on.  Cheesy
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