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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > **infamous n55 torque dip**



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      01-30-2011, 01:50 PM   #23
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Quote:
Originally Posted by shockin330i View Post
13.5psi map 1? If you can, can you send me your dyno files?


i don't have the files... i'm going back to the shop tomorrow to get them and to have them printed with STD correction so we can compare to everyone around here.

14~14.4 PSI peak falling to 11~10 PSI at 6300 RPM, again , more on this later
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      01-30-2011, 02:27 PM   #24
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Originally Posted by shockin330i View Post
Notice black - e had the same dip.
Black e only had it (the dip) on map 0 (bypass mode) but not on map 1. On his dyno, with map 1, he has no dip where the stock one has a huge one.
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      01-30-2011, 02:34 PM   #25
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Black e only had it (the dip) on map 0 (bypass mode) but not on map 1. On his dyno, with map 1, he has no dip where the stock one has a huge one.
Black e has a small dip but then corrects itself.
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      01-30-2011, 03:06 PM   #26
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i'll tell you that the the dip IS created by the stock boost control, on the stock tune the car hits 10+ PSI (boost overshoot)then tries to correct it self over and over...more on this later (read tomorrow night)
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      01-30-2011, 03:37 PM   #27
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i'll tell you that the the dip IS created by the stock boost control, on the stock tune the car hits 10+ PSI (boost overshoot)then tries to correct it self over and over...more on this later (read tomorrow night)
That's too long
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      01-31-2011, 09:37 PM   #28
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Can I get some mother f'in torque on pump gas!!!!
procede new maps....
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      01-31-2011, 09:55 PM   #29
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What's funny is that i had to drop low end boost a bit because my 7DCT was slipping under 4000rpm. As it is now, the car only runs 10-13psi under 3500rpm. Valvtronic is great.
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      01-31-2011, 10:05 PM   #30
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What's funny is that i had to drop low end boost a bit because my 7DCT was slipping under 4000rpm. As it is now, the car only runs 10-13psi under 3500rpm. Valvtronic is great.
Would the 6AT need the same boost drop?
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      01-31-2011, 10:25 PM   #31
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Would the 6AT need the same boost drop?
Nope... Neither will the 6MT. But how much torque could you possible want?
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      01-31-2011, 10:45 PM   #32
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Nope... Neither will the 6MT. But how much torque could you possible want?
I have a feeling we can hit 450tq with race and meth. I need to order a meth kit...
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      01-31-2011, 10:49 PM   #33
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I have a feeling we can hit 450tq with race and meth. I need to order a meth kit...
450tq is perfectly do-able. Will probably take 16-17psi at 3000rpm. Along with race gas/meth of course.

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      01-31-2011, 11:02 PM   #34
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Originally Posted by shiv@vishnu View Post
450tq is perfectly do-able. Will probably take 16-17psi at 3000rpm. Along with race gas/meth of course.

Shiv
Let's do it! Lol
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      02-01-2011, 10:12 AM   #35
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Quote:
Originally Posted by shiv@vishnu View Post
450tq is perfectly do-able. Will probably take 16-17psi at 3000rpm. Along with race gas/meth of course.

Shiv
sign me up!
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      02-01-2011, 11:39 AM   #36
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Originally Posted by shockin330i View Post
Can I get some mother f'in torque on pump gas!!!!
procede new maps....
thats a nice looking dyno!
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      02-01-2011, 12:20 PM   #37
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Quote:
Originally Posted by BoostedE90 View Post
Got this run from this thread...
http://www.e90post.com/forums/showthread.php?t=481075

This curve doesn't appear to have a dip...
Graph is in the OP

And if you look at the stock torque it does have the same dip. The dip seems to have been corrected in the tuned graph.
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      02-01-2011, 12:23 PM   #38
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The dip is caused by boost control. It's an issue called "integral wind-up" that happens during a low rpm, high gear pull. During low engine speeds, the DME is unsuccessfully trying to reach the boost target. So the integral component of the pId system adds full positive correction. When boost target is finally achieved, the DME still has all this positive correction that it cant get rid of quickly enough. So boost overshoots for a moment. In the BMW, this causes a throttle closure and a big recovery dip. So nope, it has nothing to do with AFR, timing, etc,. Just boost control.

Shiv
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      02-01-2011, 12:26 PM   #39
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Quote:
Originally Posted by shiv@vishnu View Post
The dip is caused by boost control. It's an issue called "integral wind-up" that happens during a low rpm, high gear pull. During low engine speeds, the DME is unsuccessfully trying to reach the boost target. So the integral component of the pId system adds full positive correction. When boost target is finally achieved, the DME still has all this positive correction that it cant get rid of quickly enough. So boost overshoots for a moment. In the BMW, this causes a throttle closure and a big recovery dip. So nope, it has nothing to do with AFR, timing, etc,. Just boost control.

Shiv
It takes 1200 RPM to correct a boost overshoot?!?! I find that hard to believe.

I'm not saying you're wrong... it's just hard to believe... Are there any datalogs to support that?

Edit: I'm sure you do. Can we see them?
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      02-01-2011, 12:29 PM   #40
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It takes 1200 RPM to correct a boost overshoot?!?! I find that hard to believe.

I'm not saying you're wrong... it's just hard to believe... Are there any datalogs to support that?
Integral (the "I" in PID) is the slowest moving correction of the 3. It's meant to make long-term offsetting changes to compensate for changes in operating conditions/hardware/etc,. It's not intended to catch spikes. That's the "D" or derivative gain. And yes, plenty of datalogs to show this.
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      02-01-2011, 12:46 PM   #41
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Quote:
Originally Posted by shiv@vishnu View Post
The dip is caused by boost control. It's an issue called "integral wind-up" that happens during a low rpm, high gear pull. During low engine speeds, the DME is unsuccessfully trying to reach the boost target. So the integral component of the pId system adds full positive correction. When boost target is finally achieved, the DME still has all this positive correction that it cant get rid of quickly enough. So boost overshoots for a moment. In the BMW, this causes a throttle closure and a big recovery dip. So nope, it has nothing to do with AFR, timing, etc,. Just boost control.

Shiv
Quote:
Originally Posted by atlharry View Post
It takes 1200 RPM to correct a boost overshoot?!?! I find that hard to believe.

I'm not saying you're wrong... it's just hard to believe... Are there any datalogs to support that?

Edit: I'm sure you do. Can we see them?
This confirms that black e was right. Its a boost over shoot. He was/is suppose to have a full write up of his finding from his dyno results today.
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      02-01-2011, 12:52 PM   #42
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Quote:
Originally Posted by atlharry View Post
It takes 1200 RPM to correct a boost overshoot?!?! I find that hard to believe.

I'm not saying you're wrong... it's just hard to believe... Are there any datalogs to support that?

Edit: I'm sure you do. Can we see them?



I'll show some logs of this later today...
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      02-01-2011, 12:56 PM   #43
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I'll show some logs of this later today...
YOu said that sunday! lol
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      02-01-2011, 02:28 PM   #44
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Quote:
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Would the 6AT need the same boost drop?
Quote:
Originally Posted by shiv@vishnu View Post
Nope... Neither will the 6MT. But how much torque could you possible want?
Shiv--why do you think this is for the DCT?

If that is an obvious question/answer I apologize.

Coming from my 2008 N54/MT 135 to the 2011 N55/DCT 135, I swear the new one feels faster stock...I think it may just be the way that the transmission shifts...
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