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Author Topic: How to make sense of and set a good boost profile  (Read 9947 times)
NOTORIOUS VR
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« on: February 27, 2014, 07:07:11 AM »

I'd like to be able to set a boost profile that is flat or increasing even, but I'm not exactly sure how to.

The attached log and graph is pretty much what I see every time, so I have to make odd adjustments to LDRXN and then make PID adjustments to keep the boost below the peaks and dips of the req. boost line.

How is ME7 coming up with the req. boost curve?  And how do I change it to something like a flat boost req. (or increasing)?  Is there a map that converts boost > load or vice versa?

Thanks!
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« Reply #1 on: February 27, 2014, 09:24:24 AM »

I would like to know this one too!!
I had an ugly boostovershoot on mine, cousing TC, but i sorted it out with DIMX. It took me like 10 revisions, but it looks pretty good now.
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ddillenger
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« Reply #2 on: February 27, 2014, 09:33:58 AM »

KFURL/KFPRG

Are what I believe you are referring to.
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NOTORIOUS VR
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« Reply #3 on: February 27, 2014, 09:36:26 AM »

I don't really have an issue with overshooting, the boost is where I want it.

what I don't understand is how to make requested boost what I actually want it to be.  I know that cam changeover, etc on the S4 plays a role in cyl filling but I still don't get why it spikes or tapers the req boost.  I'd like to run say 22 psi to red line, but to do that now I'd have to bump LDRXN in various places to make sure I can run that boost profile without overshooting the requested too much and going into limp/getting TC.

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phila_dot
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« Reply #4 on: February 27, 2014, 10:01:44 AM »

KFURL/KFPRG

Are what I believe you are referring to.

That is the conversion from load to pressure and the answer to his question, but won't help achieve his goal.

http://nefariousmotorsports.com/forum/index.php?topic=3978.msg40306#msg40306

vpsspls_w - KFVPDKSD / KFVPDKSE
fpbrkds_w - KFPBRKNW / KFPBRK

« Last Edit: February 27, 2014, 10:14:09 AM by phila_dot » Logged
nyet
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« Reply #5 on: February 27, 2014, 10:44:31 AM »

I don't really have an issue with overshooting, the boost is where I want it.

what I don't understand is how to make requested boost what I actually want it to be.  I know that cam changeover, etc on the S4 plays a role in cyl filling but I still don't get why it spikes or tapers the req boost.  I'd like to run say 22 psi to red line, but to do that now I'd have to bump LDRXN in various places to make sure I can run that boost profile without overshooting the requested too much and going into limp/getting TC.



If you want a clean boost req you have to hack the req load->pressure path.
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ME7.1 tuning guide (READ FIRST)
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« Reply #6 on: February 27, 2014, 11:48:29 AM »

I would start by logging the 5 variables that determine requested boost pressure to determine what and why it is causing the fluctuation.

Then you can decide if you want to make a change and where it should be applied.
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NOTORIOUS VR
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« Reply #7 on: February 27, 2014, 12:51:57 PM »

I'll be honest I have no idea what the 5 variables would be.

Worst part is, this (similar) issue happens to me in my 1.8T as well...

I feel I'm the only one that's having issues like this around here (that's how it feels anyway) while everyone else seems to be able to dial in a boost req. correctly, yet on 3 separate cars in the last little while (including my 1.8T) none of what is happening here makes any sense to me.  My 1.8T (w/ K04) is by far the worst offender of not doing what I tell it to.  Seemingly completely ignoring KFLDIMX, etc..

« Last Edit: February 27, 2014, 12:57:43 PM by NOTORIOUS VR » Logged

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« Reply #8 on: February 27, 2014, 01:43:30 PM »

For 2.7t ME7.1, this is all you need:

http://s4wiki.com/wiki/Tuning#Cam_changeover_effect_on_requested_boost

not sure about 1.8ts

NOTE IT IS A HACK.

I'm sure prj (or others) can tell you why it isn't the right thing to do Smiley
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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.
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« Reply #9 on: February 27, 2014, 02:23:26 PM »

For 2.7t ME7.1, this is all you need:

http://s4wiki.com/wiki/Tuning#Cam_changeover_effect_on_requested_boost

not sure about 1.8ts

NOTE IT IS A HACK.

I'm sure prj (or others) can tell you why it isn't the right thing to do Smiley

There is a list of maps, but nothing on what to do with them. If we can reach a consensus, I will summarize it and write it up for future generations.
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prj
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« Reply #10 on: February 27, 2014, 02:27:43 PM »

ME7 is a torque based system.
Who cares what the boost is? You are targeting a certain cylinder filling, in cold weather you need more boost, in hot weather less boost to accomplish the task. Also, you need different amounts of boost at different rpm.
The reason it is making your life so difficult, is because you are not doing what is intended.

That said, if you want to have flat boost request, just leave all the other maps, set LDRXN high and limit load through KFLDHBN (which is pressure ratio).
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phila_dot
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« Reply #11 on: February 27, 2014, 03:05:38 PM »

That said, if you want to have flat boost request, just leave all the other maps, set LDRXN high and limit load through KFLDHBN (which is pressure ratio).

rlsol will still be subject to the same influences. The output gets converted to load and would then potentially become rlsol. It is then subject to the same calculation and influences en route to plsol.
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nyet
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« Reply #12 on: February 27, 2014, 03:14:51 PM »

CAUTION! HACK!
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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.
phila_dot
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« Reply #13 on: February 27, 2014, 03:29:23 PM »

For 2.7t ME7.1, this is all you need:

http://s4wiki.com/wiki/Tuning#Cam_changeover_effect_on_requested_boost

not sure about 1.8ts

NOTE IT IS A HACK.

I'm sure prj (or others) can tell you why it isn't the right thing to do Smiley

Fixing the notch is easy and none of those maps need to be touched.

The notch is a clear indication that KFNW needs work.
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NOTORIOUS VR
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« Reply #14 on: February 27, 2014, 03:45:34 PM »

ME7 is a torque based system.
Who cares what the boost is? You are targeting a certain cylinder filling, in cold weather you need more boost, in hot weather less boost to accomplish the task. Also, you need different amounts of boost at different rpm.
The reason it is making your life so difficult, is because you are not doing what is intended.

That said, if you want to have flat boost request, just leave all the other maps, set LDRXN high and limit load through KFLDHBN (which is pressure ratio).
ME7 is a torque based system.
Who cares what the boost is? You are targeting a certain cylinder filling, in cold weather you need more boost, in hot weather less boost to accomplish the task. Also, you need different amounts of boost at different rpm.
The reason it is making your life so difficult, is because you are not doing what is intended.

That said, if you want to have flat boost request, just leave all the other maps, set LDRXN high and limit load through KFLDHBN (which is pressure ratio).

True, I suppose my frustrations get the best of me sometimes.  PRJ (or anyone) if you had a min to look @ the .csv and let me know if you see anything out of the ordinary?  Or maybe that I should be changing my way on going about tuning ME7?  I'd be more then happy to email the file that goes along with that log.

I suppose my main issue with all this is there's so much going on, things can get tedious sometimes with the constant logging/reading/flashing cycle that can easily eat up a few hours of time for just a few minor revisions.  Compared to live tuned systems with live data (stand alone) that I'm normally used to getting direct results.

If fixing the notch is only about playing with the cam on/off and/or cylinder fill compensation then I will give that a try.  Otherwise I'll just tune around it I suppose.

I would be really curious on how to get ME7 to accept an increasing boost (keeping TQ flat) model as well, has anyone ever thought about it?  Of course normally cylinder filling/VE drops after peak TQ and adding boost is a fantastic way to keep an extremely linear TQ curve after peak.  I"m assuming this would require more then just having LDRXN end up at some retarded high figures?
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