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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Correcting Boost overshoots in ATR



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      02-15-2013, 10:52 AM   #45
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doesnt matter the value , same process .
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      02-15-2013, 08:38 PM   #46
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Quote:
Originally Posted by Ænema View Post
OK, here we go. I'll walk you through the process of identifying where and hhow much WGDC Base changes to be made.

First thing to do is to figure out where the overshoots are happening. To do this open up the CSV file.


Then look for where your Accel Ped. Pos. goes to 99%, that will let you know when you go WOT. Then go to TPS ACT and it should be at 80%.
Then start following the log until:
-TPS ACT drops BELOW 80%
-Boost Mean ABS will overshoot Req Boost Abs(and as a consequence Act Load will overshoot Requested load)

That is where the overshoots are happening. After you know where the overshoots are occuring it's just a matter of pulling DC out of the Base tabe where those overshoots are occurring.

NOTE: this map is going off of the changes already made in the pic of the "fix" above. If your starting values are different then your ending changes will be different
So you'll pull some more DC out. Like i've said, 10%-15% is a good rule of thumb, however when you see BIG drops in TPS(like 40% readings or less) it's not a bad idea to pull a little more out.

Once your changes are finished then save the map, transfer to the AP and re-log. Rinse and repeat the process until the TPS drops are gone.
I have been messing with this some myself and the only thing im not 100% on is when changing wgdc in the table do you need to pull it all the way through the dc span say left to right or only in the box where it occurs ? hope that made sense . when I would make changes just seemed as though I started a chain reaction where I was chasing tc from one point to another .I understand all the info just fine just not sure im making the correct changes . or is this part a slight guessing game to how much and how far out to make the changes .can anyone send me a csv file of a before and after with table changes so I can get the idea of the changes made and why .
thanks guy's
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      02-15-2013, 10:41 PM   #47
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Quote:
Originally Posted by cwarren View Post
I have been messing with this some myself and the only thing im not 100% on is when changing wgdc in the table do you need to pull it all the way through the dc span say left to right or only in the box where it occurs ? hope that made sense . when I would make changes just seemed as though I started a chain reaction where I was chasing tc from one point to another .I understand all the info just fine just not sure im making the correct changes . or is this part a slight guessing game to how much and how far out to make the changes .can anyone send me a csv file of a before and after with table changes so I can get the idea of the changes made and why .
thanks guy's
You'll want to be sure to pull out DC the entire length of where throttle closures are happening and then smooth it out wit the adjacent cells. For instance you don't want a 9 right next to a 15. The goal is a smooth blending. Sometimes it fixes it the very first try, sometimes it can become a little bit of headache.
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      02-16-2013, 09:33 AM   #48
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That's how I was doing it just wanted to make sure it was correct .maybe I was just pulling to little and that's why it seemed as though I was chasing it around .
thanks man
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      06-28-2014, 03:08 PM   #49
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I love this article, and used to pull some WGDC out a year ago to correct for overshoots with my stage 1 tune. Now I'm running stage 2+, with catless DPs, and needed to pull a little more out. However, I'm under shooting at high RPMs, which is referenced in the first post, talking about adding WGDC.

My question is, I need to add when the MAF Req is between 350 and 400, which in ATR, the chart ends at 333. I'm afraid that adjusting the X values of the table would throw everything off. Any ideas?
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      09-17-2014, 03:31 AM   #50
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I have a similar question to above, here in colorado my boost setpoint factor is regularly over 2.5 the ENTIRE time, and my requested GS is regularly in the 400-500's. Given that both of those are way off the end of this table, how the heck would I go about doing this?

I do see throttle closures but they are pretty rare, its usually on a cold day and I'll get it one pull but not the next, so I just need to back out a little, just have no idea how to even fallow the given guides in this thread given how far off the chart I am.
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      09-17-2014, 03:00 PM   #51
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You can actually change the tables themselves, click in the "333" box and type 500, then interpolate horizontally. You'll probably need to re-adjust the values afterwards but once it's all done you'll have more control in the high range.
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      09-17-2014, 05:45 PM   #52
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Thanks! If I do that will the DME linearly interpolate between the new values in the chart sense we didnt increase the number of rows/columns? It sounds like you're implying that which is why I might have to interpolate the values like you were talking about.

And I just realized what you may mean is something like this:

current range is 33 - 333 (GS) in 16 columns, thus if the new range is 500 the range is 33 - 500 in 16 which would turn into: 29, 58, 87, 116, 145, 174, 203, 232, 261, 290, 319, 348, 377, 406, 435, 464, 493.... however in the table above they seem to spread out the last ones more, its +11 or so until 111 where they added +22 from the previous, then back to +12 (133) and goes like that back and fourth until they hit 333.

Edit: I'm a moron in, in the right click window there is a horizontal interpolate option that does what you're saying.

Last edited by shushikiary; 09-18-2014 at 11:16 PM..
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      11-22-2015, 03:00 PM   #53
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Great article. Any idea why my (n55) WGDC table is reversed from the OP? My values increase toward the right side (higher MAf values).
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