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Old 05-26-2014, 05:47 PM   #1
sterod
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Default Turbo Dynamics & WGDC IAT Correction

Can someone explain to me why the Turbo Dynamics section has an intake air temperature correction table when the wastegate duty cycle table already has one? To me this seems redundant. If the WGDC table will adjust as needed with temperature, then why must the Turbo Dynamics also adjust with temperature? Seems to me like the TD IAT tables (Positive,Negative and Proportional) can all be zeroed out, then just allow the TD Integral to adjust the already IAT compensated WGDC tables as needed. I can't see the need for this "double" IAT compensation.

If I'm way off here, please, educate me!
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Last edited by sterod; 05-26-2014 at 11:44 PM.
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Old 05-27-2014, 07:50 AM   #2
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http://www.romraider.com/forum/topic1814.html

heres some slight reading for you. basically TD is how the ecu fixes the boost error, wgdc is what the wastegates duty cycle is set to so you don't have that error.
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Old 05-27-2014, 08:20 AM   #3
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Yes, I know what TD does, but I'm suggesting that it will do it anyway without needing the IAT correction table. The TD Integral raises the WGDC from the base towards the high limit as needed to reach the desired boost level.
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Old 05-29-2014, 02:43 PM   #4
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Then why don't you zero out your tables and see what happens.
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Old 05-29-2014, 04:43 PM   #5
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Quote:
Originally Posted by Tripintaz View Post
Then why don't you zero out your tables and see what happens.
I did, and as expected it made tuning the WGDC and TD tables so much easier. No extra variables messing things up unnecessarily.
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Old 05-30-2014, 03:52 PM   #6
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In case you did not notice, one refers to reducing wastegate duty% and the other affecting target boost. At least in my tunes I need both as it allows better control of boost when temps vary. If yours works fine being one dimensional then that's awesome. Seems like a restriction to me though to do it that way.
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Old 05-30-2014, 11:06 PM   #7
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Yes, it definitely works well for me, I'll keep the TD IAT Tables zeroed out for now.
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Old 05-30-2014, 11:53 PM   #8
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If you could control all the variables of our environment then yeah zero out the tables. Thats not possible though so I would re enable them. When your car is under a heavier load your boost control will not be on spot.
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Old 05-31-2014, 08:45 AM   #9
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I think you are missing my original question though. The TD IAT and WDGC IAT correction tables appear to do the same thing so why have both? I asked the question, if someone can intelligently explain to me the difference I'd love to know.

WGDC IAT Compensation
[ALL 2.5L MODELS] -> This is the relative compensation (based on intake temperature) to the starting and maximum wastegate duty values as determined by the "Wastegate Duty Cycles (Low)" and "Wastegate Duty Cycles (High)" tables.

Turbo Dynamics IAT Compensation
This is the relative compensation (based on intake Temp) to the "Turbo Dynamics Integral Negative/Positive/Proportional" map value.

The WGDC adjusts the low and high, the TD adjusts the integral, but if the WGDC is already adjusting the low and high based on IAT, why bother also adjusting the TD Integral based on the temperature? Its going to hit the right value on its own and two temperature tables fighting trying to compensate makes no sense to me at all.
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Old 06-01-2014, 12:23 AM   #10
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I wish I could explain it in a clear way. However, its difficult to explain. Did you try reading the notes in ATR?
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Old 06-01-2014, 12:33 AM   #11
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http://legacygt.com/forums/showthrea...m-72638p3.html

This should help explain it better.
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Old 06-02-2014, 12:24 AM   #12
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I read the article, and while it is a good read, It doesn't mention the TD Positive/Negative/Proportional IAT Correction tables anywhere.

Yes, I read the notes in ATR, that's where I pasted the table descriptions from above.
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Old 06-02-2014, 09:48 AM   #13
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WGDC Intake temp adjustment results in a CHANGE in WGDC, Intake temp adjustment in TD section does NOT change WGDC, it changes the magnitude of adjustment in WGDC when TD is hunting for the correct value.

The WGDC Intake temp table reduces both high and low WGDC limits for cold temperatures, it decreases both high & low by the same percentage so it slides the allowable WGDC window downwards as temps get lower than 68. The Intake temp adjustments in TD expand or contract the size of the TD adjustment, so for a given boost error it will increase or decrease the magnitude of the WGDC correction based on intake temp. Lower temp = smaller adjustment. So it seems that the effect is to make TD adjust more cautiously in cold temps.

[Edit] Actually after thinking about this some more, perhaps it's just that in cold temperatures for a given boost error WGDC just needs less change to hit the correct boost.

Last edited by wchafe; 06-02-2014 at 10:28 AM.
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Old 06-03-2014, 03:33 AM   #14
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You turbo will spool faster in colder weather, so you will need 'less' turbo dynamics. I wish I had those tables.
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Old 06-03-2014, 09:35 AM   #15
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Essentially, you just gave your car less ability to regulate boost values when the temps change. It may not be apparent right now, but it will be when winter comes back. I think your adjustments were foolish. They both may have the same effect, but in different ways. Both ways are needed for varying ambient temps and engine load due to weight or going up hills.
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Old 06-03-2014, 12:56 PM   #16
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Quote:
Originally Posted by wchafe View Post
WGDC Intake temp adjustment results in a CHANGE in WGDC, Intake temp adjustment in TD section does NOT change WGDC, it changes the magnitude of adjustment in WGDC when TD is hunting for the correct value.

The WGDC Intake temp table reduces both high and low WGDC limits for cold temperatures, it decreases both high & low by the same percentage so it slides the allowable WGDC window downwards as temps get lower than 68. The Intake temp adjustments in TD expand or contract the size of the TD adjustment, so for a given boost error it will increase or decrease the magnitude of the WGDC correction based on intake temp. Lower temp = smaller adjustment. So it seems that the effect is to make TD adjust more cautiously in cold temps.

[Edit] Actually after thinking about this some more, perhaps it's just that in cold temperatures for a given boost error WGDC just needs less change to hit the correct boost.
Excellent explanation!

Quote:
Originally Posted by Tripintaz View Post
Essentially, you just gave your car less ability to regulate boost values when the temps change. It may not be apparent right now, but it will be when winter comes back. I think your adjustments were foolish. They both may have the same effect, but in different ways. Both ways are needed for varying ambient temps and engine load due to weight or going up hills.

Yes he did. But also if he's constantly monitoring his car I think it's good for the learning process so it may not be very foolish in regards to learning. I've had this question in the past and it's being answered pretty good, but he will see how this effects his tune when IAT's change.

OP, monitor closely in the morning and midday when temps are the highest. Right now here in NM I get a 40* change in weather so it's not hard to see how this effects boost.


Also, just a thought on how 'I' would do it. If I was having a hard time tuning target boost with TD IAT comps in place 'I' would zero them, tune target, then slowly add IAT comps back in. If it changes target boost again, then find where (shouldn't be hard since it's being added back slow). Just my thought process, others may do it different
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Old 06-04-2014, 10:37 AM   #17
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Good info guys thanks. I am definitely logging it and monitoring it closely. I still have them zeroed out and it's consistently hitting the boost target with the TD integral.
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