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Author Topic: PID contoller calibration from square one  (Read 153496 times)
20VTMK1
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« Reply #75 on: October 01, 2013, 12:11:21 PM »

Shocked You are the man. That is much easier than just picking values.


What are the opinions of re-scaling the axes of KFLDRL/DIMX? Are the axes shared with any other maps? Since I have a big turbo 1.8 I don't see much sense in having such high resolution from 1000-3000RPM.

EDIT: The FR says that KFLDIMX and KFLDRL are the only maps that use that RPM axis. I see no reason I can't change it, just have to make sure KFLDIMX gets changed appropriately, which is easy using prj's spreadsheet.

Any luck with this ? I was also looking at the HPA values in DIMX , in the stock BAM binary it goes only up to 1000 hpa (I assume that's 1bar gauge pressure) . Would it be worth it doing this ?
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catbed
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« Reply #76 on: October 01, 2013, 12:39:13 PM »

Any luck with this ? I was also looking at the HPA values in DIMX , in the stock BAM binary it goes only up to 1000 hpa (I assume that's 1bar gauge pressure) . Would it be worth it doing this ?

I haven't tweaked it any more as I have been pretty busy, but when I get back to the country I might give it a shot.

Maybe some others can chime in and provide some insight.
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edduu
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« Reply #77 on: October 01, 2013, 11:07:41 PM »

hi there guys, sorry for the dumb question, this can be also for correct a non overboost fault. a lost of pressure problem?

i'm fixing a poorly made map for my friend that have an 1.8t jetta, the max desired boost is already in their limits, 2550 mbar, and the boost reach it for only 1k revs then go down. this can be fixing tweaking the diverter too i think, but maybe its lowering because IAT also right?

how i can check if its because the IAT?

http://grabilla.com/03a02-cb8df034-816f-4955-95b6-fe9e115aaf83.png

thanks, i'm new at tuning Smiley
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catbed
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« Reply #78 on: October 01, 2013, 11:11:10 PM »

hi there guys, sorry for the dumb question, this can be also for correct a non overboost fault. a lost of pressure problem?

i'm fixing a poorly made map for my friend that have an 1.8t jetta, the max desired boost is already in their limits, 2550 mbar, and the boost reach it for only 1k revs then go down. this can be fixing tweaking the diverter too i think, but maybe its lowering because IAT also right?

how i can check if its because the IAT?

http://grabilla.com/03a02-cb8df034-816f-4955-95b6-fe9e115aaf83.png

thanks, i'm new at tuning Smiley

Stock k03? A k03 won't hold more than 1bar to redline, if that.
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pablo53
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« Reply #79 on: October 02, 2013, 05:25:44 PM »

Any luck with this ? I was also looking at the HPA values in DIMX , in the stock BAM binary it goes only up to 1000 hpa (I assume that's 1bar gauge pressure) . Would it be worth it doing this ?

Rescale the hpa axis evenly so the last column is a touch higher than the max boost you plan to run.   This gives the most resolution while still covering your full range of manifold pressure.
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20VTMK1
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« Reply #80 on: October 03, 2013, 12:21:11 PM »

Pablo ,

Thank you !

Am I correct in saying that the axis is plsolr_w  , defined as "relative target(desired) charge pressure" , which is manifold pressure less ambient = gauge pressure ?

Thanks
« Last Edit: October 03, 2013, 01:22:18 PM by 20VTMK1 » Logged
pablo53
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« Reply #81 on: October 05, 2013, 01:12:00 AM »

Am I correct in saying that the axis is plsolr_w  , defined as "relative target(desired) charge pressure" , which is manifold pressure less ambient = gauge pressure ?

I can't state with full knowledge that psolr_w is the correct variable the axis uses, but gauge pressure in mbar or kpa (which ever you prefer to use) is right.   

My KFLDIMX hpa axis is stock.... while running with the 5120 hack and 4 bar MAP sensor so the axis is in effect doubled.   

250 mbar ~ 7 psi, 1000 mbar ~ 29 psi. 
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Nottingham
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« Reply #82 on: November 22, 2015, 11:18:35 PM »

So, did anyone achieve any real results by using this method or is it just a theory?

I mapped out the boost at various fixed duty levels using KFLDRAPP. The WG on the turbo has rather small operating range (around 15% - 45%) so I tested with small intervals.
While the boost response to the fixed duty cycle is sane, the values calculated for KFLDRL based on the results are not.

It didn´t make any other difference besides increasing the delta between ldtvr_w (pre-lin) and ldtvm (post-lin). Even with PID already shut down (B_lddy = 0) the ldtvr_w doesn´t follow KFLDIMX at all.
With plsolr_w at 1000mbar, ldtvr_w output is lower than KFLDIMX specifies for the pressure (28% vs. 35%). The modifications are not coming from KFLDIOPU, LDIATA or KFLDIWL either as these maps are zero by default.

Basically I am trying to get overboost in control. The boost always spikes 300-400mbar higher than requested, eventhou KFLDIMX contains the correct values which are required to keep the boost stable at the specific plsolr levels.
The problem is that I cannot get the ECU to follow these values. In regions where the turbo wakes up (2700 - 3200rpm) the desired duty cycle is exceeded and at higher rpms (>5500) it droops down. PID isn´t too helpful in
controlling the boost spike, since lde has reached zero (B_lddy = 0) and the PID has entered in stable state therefore making little to no difference.

The turbo I am using has somewhat similar characteristics as K04-064, however the waste gate characteristics are drastically different.
According to VAG the actuator of K04-064 starts to crack at 300mbar, has total travel of 13mm and has "calibration pressure" of 500mbar with 4.25mm travel.

The waste gate on this F23T hybrid turbo starts to crack at 483mbar and it is able to hold around 572mbar with 0% duty.

When looking at the stock KFLDIMX map of a car using this K04-064 turbo (S3), it is clear that the map is perfectly linear until 3500rpm.
Even at the higher RPMs the deviation from linear is only couple percent.
« Last Edit: November 22, 2015, 11:20:07 PM by Nottingham » Logged
DT
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« Reply #83 on: November 23, 2015, 01:01:52 AM »

Compare different N75 valves, inner diameter and flow capability varies.
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Nottingham
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« Reply #84 on: November 23, 2015, 01:13:04 AM »

There is only one N75 model for TFSI.
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wannabee900
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« Reply #85 on: November 23, 2015, 02:47:49 AM »

Didn't read full thread but is the tfsi N75 physically different from the old style eg. 1.8t vw oem N75? Does it have to be a TFSI N75?
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Nottingham
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« Reply #86 on: November 23, 2015, 03:11:41 AM »

Yeah, the TFSI and TMPI N75s are completely different.
You could probably make an adapter, but I don´t think the issue has anything to do with the N75.

Most likely the wastegate actuator (which came with the turbo) itself is a POS. It is some sort of crappy adjustable "high lift" actuator, which has significantly higher cracking pressure / different travel than the OEM ones.
It´s cracking pressure varies depending on the temperature and generally it feels like it is extremely sensitive.

But regardless, IMO the method described in this thread for calibrating the KFLDRL doesn´t appear to provide any sane values. I´m pissed about the fact that there is no real information about it Angry The few phrases in FR and the patents mentioning it are useless.
However based on the FR it seems like KFLDRL is something that is calibrated by trial and error, and isn´t anything you can just calculate based on other measurements.

Regardless, the boost control in MEx. is a huge let down to me.
 
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nyet
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« Reply #87 on: November 23, 2015, 03:10:42 PM »

You'll have to do a lot more than simply modifying KFDRL. Why would you assume that is the only map you have to modify?

You're only allowed to be "disappointed" in a PID if you actually understand how PIDs work and how to program them.
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prj
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« Reply #88 on: November 23, 2015, 03:24:28 PM »

However based on the FR it seems like KFLDRL is something that is calibrated by trial and error, and isn´t anything you can just calculate based on other measurements.
You could not be more wrong. The FR describes exactly how to fill it. Those of us who understand this have made tools to calculate it based on measured boost. There is absolutely 0 guesswork involved.
Boost PID calibration is fairly simple in ME7/MED9 once you know what you are doing.

The pilot logic is crap in that it is an I limiter, not a true pilot map like on EDCxx.
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Nottingham
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« Reply #89 on: November 23, 2015, 10:31:51 PM »

I´ve looked into the calculation sheet prj posted, and my values are calculated in the same way.

Check the attachment, you can see my cropped tables in there.

When these values were used, the pre-lin value dropped significantly.
Even with psolr slightly over 1000mbar ldtvr_w never raised above 28.5%. Meanwhile the linearized value (ldtvm) stayed around where it should be.
The boost was even more erratic compared to situation where linearization is disabled.

With linearization disabled (KFLDRL 1:1) ldtvr_w is pretty constant with KFLDIMX, however once the PID enters stable state (B_lddy = 0) the ldtvr_w and ldtvm (obviously) overshoot heavily.


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