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Technical Topics B48 4-Cylinder Turbo Engine / Drivetrain / Exhaust Modifications Downpipe + tune

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      12-22-2021, 09:04 PM   #1
dvniellee
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Downpipe + tune

So I plan on getting the VRSF catless downpipe. I have the 2021 330i B46 and obviously I can’t use bm3 cause of the bench. What other tune did you guys use? Also what’s up with guys having the car shake and rattle at a certain gear or in different driving modes?
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      12-23-2021, 08:29 AM   #2
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Quote:
Originally Posted by dvniellee View Post
So I plan on getting the VRSF catless downpipe. I have the 2021 330i B46 and obviously I can’t use bm3 cause of the bench. What other tune did you guys use? Also what’s up with guys having the car shake and rattle at a certain gear or in different driving modes?
I don't know about all the shaking and rattling but I have the Armytrix catless DP (prototype version) with a custom map 6 tune with an E85 blend on JB4 on MY2020 330i and have been loving it. I am sure that I am not getting the most out of it compared to a flash tune but it's plenty for me.

What's funny is that I have yet to get a CEL from the DP and I am not running any sort of O2 spacer. Guess I got lucky.
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      12-23-2021, 09:30 AM   #3
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I recommend the active autowerke catted downpipes instead, no CEL, no fuel smell.
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      12-23-2021, 07:25 PM   #4
MidnightShadow330
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Quote:
Originally Posted by dvniellee View Post
So I plan on getting the VRSF catless downpipe. I have the 2021 330i B46 and obviously I can’t use bm3 cause of the bench. What other tune did you guys use? Also what’s up with guys having the car shake and rattle at a certain gear or in different driving modes?
I'm guessing the car shaking at a certain gear, you got that from my post. To this day I still don't know what the problem is or even if I'm the only one with this problem. The problem did however start after I added the VRSF downpipe. Every time the car has to start building boost at lower rpm, especially in 8th gear, it starts shaking between exactly 1500 and 1900, as soon it hits 2k it stops. However, if the car downshifts from 8th to 7th, then nothing happens, and it's really smooth. I'm so baffled I don't know what's wrong with it.
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      12-24-2021, 09:33 AM   #5
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Originally Posted by MidnightShadow330 View Post
I'm guessing the car shaking at a certain gear, you got that from my post. To this day I still don't know what the problem is or even if I'm the only one with this problem. The problem did however start after I added the VRSF downpipe. Every time the car has to start building boost at lower rpm, especially in 8th gear, it starts shaking between exactly 1500 and 1900, as soon it hits 2k it stops. However, if the car downshifts from 8th to 7th, then nothing happens, and it's really smooth. I'm so baffled I don't know what's wrong with it.
Did you take it to a mechanic?
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      12-24-2021, 03:04 PM   #6
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Originally Posted by mike@x-ph.com View Post
Did you take it to a mechanic?
I haven't. However, someone said this about my problem "I have had this happen a few times and I was stock. I find the shifting response isn't aggressive enough sometimes in comfort and never aggressive enough in eco….but I get it, eco should only be used cruising on a highway. But it just puts too much load on the engine". So I'm guessing it's a problem with the car in general and the downpipe just exposes the problem even more.
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      12-24-2021, 10:48 PM   #7
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Quote:
Originally Posted by MidnightShadow330 View Post
Quote:
Originally Posted by mike@x-ph.com View Post
Did you take it to a mechanic?
I haven't. However, someone said this about my problem "I have had this happen a few times and I was stock. I find the shifting response isn't aggressive enough sometimes in comfort and never aggressive enough in eco….but I get it, eco should only be used cruising on a highway. But it just puts too much load on the engine". So I'm guessing it's a problem with the car in general and the downpipe just exposes the problem even more.
I've never had that problem. Changing a down pipe alters the back pressure and could exacerbate some things. Likely the case. Cars these days are tuned for specific parameters and adjusting even the simplest of components can cause issues. Still worth a check by a tech, I'd say.
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      01-06-2022, 06:47 PM   #8
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Hello,

Anybody know if g20 b46 downpipes fit on the g22 b46? (4 series)

currently on Stage 1 map 4 jb4 and love it, but want more

thank!
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      01-07-2022, 09:55 AM   #9
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Originally Posted by 112kmsport View Post
Hello,

Anybody know if g20 b46 downpipes fit on the g22 b46? (4 series)

currently on Stage 1 map 4 jb4 and love it, but want more

thank!
Depends on the brand, the majority of them use the same downpipe for both models
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