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Author Topic: Questions regarding load limiting  (Read 7483 times)
masterj
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« on: January 26, 2012, 03:15:20 PM »

Hey everyone! Smiley

I have few questions regarding few maps with load/boost limiting...
KFLDHBN - What is turbo pressure ratio and how to convert it to pressure? (boost + ambient, in bar)
RLKRLDA - What does this map? Google translate gave me "rl threshold for slow LDR-intervention (adaptation)". What is "rl" and "SLOW (FAST?) LDR-intervention"??
KFTARX, KFTARXZK - I've set those maps to 1's. Anyone else thinks that this is really useless to limit your load based on IAT? Are there better strategies??

And KFKHFM. How can I convert it's values to % to know how much it enriches/leans AFR and that way to fix part throttle trims?

And thanks, everyone! Smiley
« Last Edit: January 26, 2012, 03:25:50 PM by masterj » Logged

nyet
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« Reply #1 on: January 26, 2012, 04:07:37 PM »

KFLDHBN - What is turbo pressure ratio and how to convert it to pressure? (boost + ambient, in bar)

pressure ratio is typically turbo outlet/inlet pressure. There is no "easy" calculation for what you want. At minimum, you have to figure out intake drop (filter etc.) before inlet, and IC and throttle plate drop before intake manifold. You could assume all are zero. But really you should probably learn a bit more about how FI systems are designed first. Motronic does all these calculations. You could log all the appropriate values (once you've figured out what they're called and where they are).

Quote
RLKRLDA - What does this map? Google translate gave me "rl threshold for slow LDR-intervention (adaptation)". What is "rl" and "SLOW (FAST?) LDR-intervention"??

If i had to guess, fast is throttle plate closure, slow is wastegate intervention (possibly through PID set point decrease) or direct N75 signal intervention (unlikely)

Quote
KFTARX, KFTARXZK - I've set those maps to 1's. Anyone else thinks that this is really useless to limit your load based on IAT? Are there better strategies??

All my opinions on the matter are on the s4wiki.

Quote
And KFKHFM. How can I convert it's values to % to know how much it enriches/leans AFR and that way to fix part throttle trims?

Don't guess, log
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sn00k
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« Reply #2 on: January 26, 2012, 04:09:40 PM »

And KFKHFM. How can I convert it's values to % to know how much it enriches/leans AFR and that way to fix part throttle trims?

(X * 0.007813 -1) * 100

i used this formula in my first me7 xdf when i made it, and it seems to work just fine..  Smiley
« Last Edit: January 26, 2012, 04:11:54 PM by sn00k » Logged
masterj
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« Reply #3 on: January 26, 2012, 04:14:31 PM »

(X * 0.007813 -1) * 100

i used this formula in my first me7 xdf when i made it, and it seems to work just fine..  Smiley

GREAT! Smiley Thank you very much!
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masterj
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« Reply #4 on: January 26, 2012, 04:19:03 PM »

pressure ratio is typically turbo outlet/inlet pressure. There is no "easy" calculation for what you want. At minimum, you have to figure out intake drop (filter etc.) before inlet, and IC and throttle plate drop before intake manifold. You could assume all are zero. But really you should probably learn a bit more about how FI systems are designed first. Motronic does all these calculations. You could log all the appropriate values (once you've figured out what they're called and where they are).

Let's say for most basic formula what it would look like? (when all the smaller factors are (let's say) zeroes)
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nyet
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« Reply #5 on: January 26, 2012, 04:24:23 PM »

In that case, PR = boost/ambient... but that is a terrible, terrible approximation

Again, PLEASE consider buying a book about FI.....

http://s4wiki.com/wiki/Compressor_map#Pressure_Ratio
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ME7.1 tuning guide
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masterj
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« Reply #6 on: January 26, 2012, 04:37:21 PM »

In that case, PR = boost/ambient... but that is a terrible, terrible approximation

Again, PLEASE consider buying a book about FI.....

http://s4wiki.com/wiki/Compressor_map#Pressure_Ratio

Thank you! Now I understand approximate values of my KFLDHBN map!
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masterj
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« Reply #7 on: January 26, 2012, 04:53:40 PM »

Ok, now another question arises... Cheesy I know that it is annoying for you all to answer them, but I really am thankful for your patience..

I've edited KFMIRL, KFMIOP, LDRXN... well, all the standart maps. But when I was driving the other day other passat 1.8T (same setup, KO3 turbo) that was tuned by pro tuner, it had very nice habbit of boosting up to 1bar in FIRST GEAR! Now my car doesn't start to boost completely until second gear (first gear - limit at 0.5bar)... So, is there a map that prevents full boost in first gear? (aka some kind of protection or something)
« Last Edit: January 26, 2012, 04:55:11 PM by masterj » Logged

nyet
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« Reply #8 on: January 26, 2012, 05:02:50 PM »

Don't guess, log
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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
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