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 Post subject: Re: How does max wgdc influence turbodynamics
PostPosted: Wed Oct 03, 2007 1:51 pm 
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mickeyd2005 wrote:
Does the global WGDC maximum cap the maximum TD integral and TD proportional? It looks like it on the LGT. For example, if max WGDC is 90% and WGDC init is 75% then the maximum that TD can be is 15%.

It caps the value from the 'Max Wastegate Duty' table (post-compensation) which would have the same effect.

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In addition, TD Proportional has priority over TD Integral. So, in this case, if the boost error was 10 psi and the TD proportional was 14% then the maximum the the TD Integral can be is 1%. TD Integral won't increase until the TD proportional drops or WGDC Init drops.

If the above is true, it can be a useful tool to control the WGDC integral from summing until boost error is within a set target.

The above only seems to apply to the global WGDC maximum. The WGDC Max Table values doesn't appear to limit the TD values. The WGDC Max Table seems to clip the total WGDC. For example, if the WGDC init = 60% and total TD = 20% but if WGDC Max Table is 70% then the resultant WGDC would be 70%. The TD values would still be in the ecu and the TD Integral would sum as normal.

The final wgdc by Max WG Duty (which itself is limited by the "global" cap). That is, the TD corrections are just other variables in the calculation along with initial wg duty. The sum of these variables will always be compared to max wg duty and therefore capped by it, regardless of the individual values.

I don't remember seeing anything that would indicate that TD prop takes priority over TD integral in a way that you described, although I would be interested in seeing logs to this effect. Perhaps I missed something.


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 Post subject:
PostPosted: Wed Oct 03, 2007 2:22 pm 
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Here are two logs.

In the log labeled, RomRaiderlog_20070924_3rd.csv, I had the proportional too high (14%), you can see that below 2864 rpm, the TD integral couldn't windup because the TD proportional was blocking it. Maybe because the TD proportional was calculated first? IDK.

In the second log labeled, RomRaiderlog_20070926_3rd.csv, I reduced the maximum proportional to 8.5% and you can see that the TD integral is now allowed to windup but only by as much as allowed by WGDC init. Ignore the blip at 2578 rpm, I believe that was due to the WGDC by rpm table.

If this is true, it seems like a good way to control TD Integral Windup.


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 Post subject:
PostPosted: Wed Oct 03, 2007 3:08 pm 
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Allright, I think I know what is going on, but I'll have to check some stuff further, so the following is from what I remember from messing with some of the LGT's unique logic.

With the roms like the LGT that actually make use of the initial wg duty alternate table, a constant is sometimes added AFTER being capped by max wg duty. Most roms, this is zero, however with the LGT and some others, it is 0.2. This is why you are seeing a max of 90.2% in these logs. This is important because TD integral positive will not be used if current wgdc > max wg duty (this is something I thought wasn't important before because with most roms this will never occur). Note that it will not clear TD integral cumulative if this is the case, just not add to TD integral cumulative if boost error continues to be positive and wgdc continues to be above max wg duty. The dip in the log dropped wgdc below max wg duty and therefore, TD integral positive was now used briefly until the next line where wgdc was 90.2% again. It held this value because TD integral pos table was not being utilized again. Not until wgdc drops below 90.2%, do we see TD integral ramp up to its max 15% as it should (note: the parameter values are slightly out of sync which is normal due to the way SSM logging is handled by the ecu).


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 Post subject:
PostPosted: Wed Oct 03, 2007 3:19 pm 
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Thanks for the explanation. That really explained why the 4.91 was added on the second log. I wanted to make sure I understood it rather than guessing.

BTW, do you know what the time interval is for the TD intgral cumulative to be updated?


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 Post subject:
PostPosted: Wed Oct 03, 2007 3:33 pm 
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TD integral cumulative will be updated at the same time as TD proportional. That is given that both are being used during the same execution (TD integral also has to meet thresholds for boost error besides the issue mentioned above). But I don't have a number as far as how many times this code is executed over time.


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 Post subject:
PostPosted: Wed Oct 03, 2007 5:28 pm 
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What values did you have in the alternate wastegate duty table for those logs?


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 Post subject:
PostPosted: Wed Oct 03, 2007 5:52 pm 
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What do you mean alternate? Are you talking about the WGDC by rpm table or are you talking about WGDC initial table?

This was the last rom that BigHonu posted. later, he changed the max value in TD proportional from 14 to 8.5.

http://www.RomRaider.org/download.php?id=3539

from this thread:

http://www.romraider.com/forum/viewtopic.php? ... &start=105


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 Post subject:
PostPosted: Fri Oct 12, 2007 4:54 pm 
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I need to clarify something about where I discussed td integral positive being disabled a few posts back. I said that if current wastegate duty is greater than max wastegate duty, then further td integral positive is not allowed (this would only potentially occur with certain roms).

This is true, however I just realized that it also is disabled when current wastegate duty is equal to max wastegate duty. This would apply to all roms. I've updated the original post with this detail. I also had updated it last week to make everything else a little clearer.


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 Post subject: Excellent post.
PostPosted: Thu Nov 08, 2007 11:22 am 
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Thanks for helping people like me figure out my ecu.


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Thu Jan 22, 2009 1:53 am 
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the boost goes to 1.5 bar for a short time (minisecond) and keep at 1.3 bar. what do you call this? is it done by the WGDC?

when i start running from 1st gear and goes up to 5th gear, the boost i change gear everytime is ok. but when i driving at 70km/h in 5th gear and i suddenly down to 3rd gear and WOT. the boost goes to 1.6X. and back to 1.3 bar. why there is a difference between these two circumstances?


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Wed Apr 15, 2009 2:39 pm 
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What if logged target boost is very far off from what is specified in target boost A and B tables? I see about 4-6 psi difference in my logs. I have no compensation specified for coolant and the atmospheric multiplier determination and offset are .05208 and .25 which I think are the default values. What else can adjust that target boost?

A log showing the issue: http://i241.photobucket.com/albums/ff125/truck0321/log2.jpg

I've also posted this on Nasioc: http://forums.nasioc.com/forums/showthread.php?t=1743466

I have TD integral minimum set to 0 in this map, it was set to -8 when the log was taken. I know this is dangerous and I'm treating the car accordingly.

EDIT: ROM REMOVED. READ THE RULES BEFORE POSTING!


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Wed Apr 15, 2009 2:57 pm 
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That's a Cobb ROM dude. You can't post that on here. Read the forum rules before posting anything.

As far as why it doesn't match up, log your atmospheric pressure and post it up.


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Wed Apr 15, 2009 3:04 pm 
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Also, what exactly are you tuning this ROM with? It is a Cobb ROM, are you using Cobb's software? If not, then your issue could be that Cobb's RT code forces the use of one of the boost tables (and initial WGDC IIRC) that are not used by the factory ECU normally and therefore not defined in RomRaider. That is, you will not be able to use RomRaider to tune target boost with a Cobb ROM.


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Thu Apr 16, 2009 4:07 pm 
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I did read the rules and if I knew that was a cobb map I would not have posted it. That might explain some of the funky behavior. My car was originally protuned but my AP died and told my tuner to go open source. Turns out he left the cobb map on there and neglected to tell me. This was a V1 protune(obviously, since a V2 would have locked me out) so is the fix as as simple as flashing an actual open source map? Incidentally, how can you tell that is a cobb map?


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 Post subject: Re: Turbo dynamics and boost control explained
PostPosted: Thu Apr 16, 2009 4:20 pm 
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truck0321 wrote:
I did read the rules and if I knew that was a cobb map I would not have posted it. That might explain some of the funky behavior. My car was originally protuned but my AP died and told my tuner to go open source. Turns out he left the cobb map on there and neglected to tell me. This was a V1 protune(obviously, since a V2 would have locked me out) so is the fix as as simple as flashing an actual open source map? Incidentally, how can you tell that is a cobb map?

They make very specific changes to the ROM in order to support RT tuning that would never be present in an OS tune, so it is quite obvious if you know what you are doing.

You would have to find a stock ROM compatible with your car/ECU and tune it with RomRaider/Ecuflash and then flash that to the car (or start with a base map that is available in the base map section).

Also, had you read all the rules, you would know that you also can't post any ROM unless it was 100% tuned by yourself starting with a 100% stock ROM or one of the OS base maps that also follows the rules. So, even if that wasn't a Cobb ROM, it still wouldn't be alllowed because it was protuned by someone else.


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