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Author Topic: Boost PID tuning  (Read 59125 times)
jibberjive
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« Reply #15 on: April 09, 2011, 12:34:48 PM »

I have spent around 10hours on the rolling road dialing in the N75 map table
Wow, 10 hrs.  Do you own a shop, or were you paying for those?  I'm curious to see how this all irons out.

I think we just need to take this info and experiment with it.  Use an mbc for safety.  I just tuned an rs6'ed s4 today, 24 psi, Ev14 injectors, 90 mm maf.... the base file pulls like crazy, I can't wait to dial it in.
I'm really starting to get a feel for this stuff.
Many Thanks to those who guide us newbies in the right direction.

What size EV14's?  What rail pressure?
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judeisnotobscure
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« Reply #16 on: April 09, 2011, 02:18:02 PM »

What size EV14's?  What rail pressure?

6o lbs @ 4 bar
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I have a b5 s4
but i just want to dance.
jibberjive
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« Reply #17 on: April 09, 2011, 03:02:46 PM »

Nice.  And thanks for your email the other day.  I'll be in touch for sure when some more of my hardware starts coming in Smiley
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Tony@NefMoto
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« Reply #18 on: April 19, 2011, 02:13:38 PM »

I found that I was only able to really tune the PID controller when I was able to data log each of the different terms in it. When you can data log the P, I, and D separately you can determine which part of the equation is affecting the result at any given moment.

Granted, you need a data logger that can log specific RAM variables. ECUx doesn't define any of the PID values, and I still haven't found the time to release my data logger. Tongue
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jibberjive
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« Reply #19 on: April 21, 2011, 03:47:40 AM »

Granted, you need a data logger that can log specific RAM variables. ECUx doesn't define any of the PID values, and I still haven't found the time to release my data logger. Tongue

ETA??
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Tony@NefMoto
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« Reply #20 on: April 21, 2011, 01:17:23 PM »

Granted, you need a data logger that can log specific RAM variables. ECUx doesn't define any of the PID values, and I still haven't found the time to release my data logger. Tongue
ETA??

I just need to write the user interface for it, so it should only be a few days to get a basic version done. The trouble is that I'm busy trying to fix a few bugs that come up with flashing in cars that have poor K-line connections. I also am trying to finish getting the website moved to another server and getting some more info put on the site.

So I will say, that I can hopefully release something with a basic user interface in two weeks to a month.
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jibberjive
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« Reply #21 on: April 21, 2011, 01:31:57 PM »

Cool. I'm not stressed cause I've got ECUx, but it'll be nice when you get around to it.  I'm not computer guru, but if there's something I can help with whenever, let me know Smiley
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em.Euro.R18
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« Reply #22 on: May 14, 2011, 06:29:18 PM »

I have an issue with overshooting my requested boost level. Requested will be 22psi and I will spike and hold 35psi. Originally my requested matched my actual during my first attempt but I was lean as hell so I made the adjustment in my main fuel scaling map. Next log I took it spiked over 35psi. I'm lost. Even in the quick settings I reduced requested boost by 20 % and it still never changed.
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Tony@NefMoto
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« Reply #23 on: May 16, 2011, 12:13:20 PM »

I have an issue with overshooting my requested boost level. Requested will be 22psi and I will spike and hold 35psi. Originally my requested matched my actual during my first attempt but I was lean as hell so I made the adjustment in my main fuel scaling map. Next log I took it spiked over 35psi. I'm lost. Even in the quick settings I reduced requested boost by 20 % and it still never changed.

If you are requesting 22psi and overshooting to 35psi, then you are likely running more pressure then the MAP sensor can read. The MAP sensor cannot read above 22psi, so if you ask for 22psi and you get anything above 22psi, the ECU is happy.

To properly use the PID to control boost pressure, you must stay below the max limit of the MAP sensor, otherwise it cannot detect when you overboost.
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nyet
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« Reply #24 on: May 16, 2011, 12:44:23 PM »

If you are requesting 22psi and overshooting to 35psi, then you are likely running more pressure then the MAP sensor can read. The MAP sensor cannot read above 22psi, so if you ask for 22psi and you get anything above 22psi, the ECU is happy.

To properly use the PID to control boost pressure, you must stay below the max limit of the MAP sensor, otherwise it cannot detect when you overboost.

Also, it is worth pointing out (again) that if you are using a stock DSLOFS, the maximum possible requested boost is HIGHER than the limit of the map sensor, which means the ECU will be happy with ANY amount of boost if your requested boost is maxed.
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ME7.1 tuning guide
ECUx Plot
ME7Sum checksum
Trim heatmap tool

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 ex
damos07
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« Reply #25 on: October 31, 2011, 04:51:57 AM »

Which maps are necessary to tune P,I and D boost regulator parameter to make boost overshoot lower?
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Rick
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« Reply #26 on: October 31, 2011, 01:03:58 PM »

I would start with lowering KFLDIMX
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damos07
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« Reply #27 on: October 31, 2011, 04:49:09 PM »

I would start with lowering KFLDIMX

What if it is not enough?
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Rick
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« Reply #28 on: November 02, 2011, 02:00:56 PM »

Then you go back to first principles with the PID tuning - first pass might be to half the P and I terms.  What is the specific issue, when did the boost spike start?   You may have a load issue.

Rick
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Bische
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« Reply #29 on: August 04, 2012, 08:02:55 AM »

Im in the process of tuning and understanding my boost regulation, I think I got a pretty good basic understanding but I want discuss and clear a few things up.

P = Corrects current error between setpoint and actual?
I = Corrects for predicted large errors, ie. In this application for quickly ramp up in pressure?
D = Corrects for predicted overshoot?

Currently im riding the I limit during spoolup with 0 P, and I have the I to drop dead after setpoint is reached, and then correcting with P and D when boost is "stable". My I limit is pegged at 95% until 3600rpm where is setpoint is reached, then drop right down to into low 20's at 3700rpm.

Is this how it is supposed to work? Or is it supposed to run both P and I during big transitions?
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