Looking for advice on tweaking boost control on my DIY tune. G30 540i on stock turbo and flex fuel tune.

mikesrex

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Mar 11, 2018
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Hi everyone, i picked up a 2017 540i and threw on a DS2.5 and downpipe, along with a flex fuel sensor. I’ve been gradually turning the car up to what I think is max effort for this setup. When the car upshifts I’m getting boost overshoot and the throttle closing a bit. I could probably raise the load ceiling to avoid throttle closure but would still like to dial in my boost control. Here’s an example of a quarter mile hit on the street. The car has gone low 11s on a drag radial, but this particular run is on a hard street tire. Traction control kicks in quite a bit from the launch. Car is at 4050 lb with driver.

Also has quaife LSD and a custom Sutphin tune.


My goal is to learn how to dial in the custom wgdc tables to get better boost control. Time is currently using a 3d boost table to target boost.

I would rather finish my DIY tune than simply pay someone for a custom tune. I am willing to pay for help with my DIY tune if that’s what it takes. I like the challenge of figuring this out and feel i will get my best quarter mile ET by being able to tweak my tune at the race track. Goal is to max out the stock turbo to get best ET. Then i may upgrade to a slightly bigger turbo. Would like to beat my F10 535ix that runs 10.7@127. I plan on putting my G30 on a diet when the time comes to get best ET.
 

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mikesrex

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Mar 11, 2018
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One thing i noticed is my load ceiling is 220 on the log but 240 in my tune. The only instance of 220 i can find in the tune is that the load to torque table maxes out at 220. I rescaled this table to max out higher. I do notice that the equivalent table in my F10 tune maxes out at 250.
 
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wheela

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One thing i noticed is my load ceiling is 220 on the log but 240 in my tune. The only instance of 220 i can find in the tune is that the load to torque table maxes out at 220. I rescaled this table to max out higher. I do notice that the equivalent table in my F10 tune maxes out at 250.
I think rescaling your load to torque table out further like you did should take care of it. Let us know how it turns out👍
 
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mikesrex

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I think rescaling your load to torque table out further like you did should take care of it. Let us know how it turns out👍
you are correct! I could only do a short test, since roads are wet today. This shows the load target going up above 220 now. Will test out a quarter mile hit next chance I get on a dry road. I might as well throw on the drag radials to help with traction.
 
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SLOWESTN54

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you are correct! I could only do a short test, since roads are wet today. This shows the load target going up above 220 now. Will test out a quarter mile hit next chance I get on a dry road. I might as well throw on the drag radials to help with traction.
what's your 60'ft like. Best i've done in my M340 is 1.60 currently. My Friend in his 540i has ran a 1.49. Both of us are on all seasons tho.
 
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mikesrex

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on open diff and soft launch on prep i was getting 1.6 60 foot. I think best ET for the car so far is 11.3@120 on that soft launch on prep. The car was on a little less boost than it is now. I wanted to try more launching that day at the track, but the track was really busy. I expect to get better traction with the LSD. On open diff you could hear one of the tires squealing almost the whole way down the track. Running some 18x9 mercedes wheels with 275/40r17 Nitto 555R2's for traction. Hoping to get 1.5 60' like my F10 535ix does on a hard street tire. This 540 really feels like it wants to haul ass. Even with throttle closures on the upshifts the car felt a smidge faster than my 10 second F10 from a roll. 60-130 times have it slightly quicker than my F10 when both cars are full interior. Once the road is dry I will post how things are going with the rescaled load to tq table and the LSD.
 

SLOWESTN54

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Dam interesting. I tend to run a 11.03 ish if I pull a 1.60 ish 60’. My friends 540 confuses me he’s been 10’s plenty. We both on ots tunes
 

mikesrex

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Mar 11, 2018
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Dam interesting. I tend to run a 11.03 ish if I pull a 1.60 ish 60’. My friends 540 confuses me he’s been 10’s plenty. We both on ots tunes
what's your setup and trap speed? I'm hoping for a lower 11/high 10 once I get the car hooking up and properly tuned on the stock turbo
 

mikesrex

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Went to the track yesterday. Managed to practice launching with the LSD and drag radials.


This is on my conventional boost control.

I did start playing with the custom WGDC, P, and D tables. The car runs well from a roll but is slow to build boost off the line. The boost target starts off very low. I have not tweaked the custom WGDC table to work well at the lower boost settings yet. I’m not sure why the target starts off that low but will get the car dialed in at the lower boost levels to see what happens from a standstill. The cool thing is this flaw might actually help for running on the street lol. At the track i had no problems with spinning.
 

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mikesrex

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Here's a log from when I used a revision that runs custom WGDC, P, and D tables. This tune works well from a roll, but this is the first time I tried it from a dig. Looks like I need some more tweaking on the lower boost targets, since the car targets slightly lower boost during the launch.

 

mikesrex

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Mar 11, 2018
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filled in the lower boost settings on the custom wgdc table and can launch the car without sluggish boost. I can't hook on the street from a dig but did want to test the 2-3-4-5 shifts. Have the car running ok without throttle closure. I really need to put it on a dyno to see where the power is at different boost levels. Not really sure if more boost = more power at the 22-25 psi range. Does anyone have any experience with maxing out a B58 gen 1 stock turbo?

Here's a 2-3-4-5 with a little bit of spinning:

 
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