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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 > N54 Exhaust Low Pitched "Farting Sound"



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      05-01-2020, 10:22 PM   #1
SixSix
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N54 Exhaust Low Pitched "Farting Sound"

I tried looking through threads to figure out what this noise is, but I can't seem to find much about it. I recently installed MMP 3" Catless Downpipes (I have made sure there are no exhaust leaks). The car does not have secondary cats either. When downshifting in low RPMs, around 1500 the engine will make a sort of low pitched farting noise. It also makes this noise when giving moderate throttle at around 1500-1800rpms. It doesn't feel like there is a loss of power but the noise is quite different from the normal exhaust note, so it's slightly concerning. I will try to get a video tomorrow.
Any info on this would be much appreciated.
Sorry if this thread is in the wrong place, I'm fairly new to posting on forums.
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      05-02-2020, 09:23 PM   #2
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Does it only happen when shifting?
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      05-02-2020, 09:29 PM   #3
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Quote:
Originally Posted by ky0u View Post
Does it only happen when shifting?
It happens when downshifting in low rpms (rev matching) and also when moderately accelerating in low RPMs.
It does not happen while upshifting. It will only make the noise when there is load on the engine at around 1500 RPMs or lower
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      05-02-2020, 09:48 PM   #4
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Normal Exhaust Note


Low Pitched Exhaust Note
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      11-22-2022, 10:50 AM   #5
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Quote:
Originally Posted by SixSix View Post
Normal Exhaust Note


Low Pitched Exhaust Note
My friends N54 135i is making this exact noise in the same scenario, did you ever find the issue?
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      11-22-2022, 10:51 AM   #6
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Hi,

I have the same issue, I wondered if you got to the bottom of it?

Driving me mad

Thank you
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      11-22-2022, 07:51 PM   #7
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Uh, just sounds like a loud raspy N54 to me?

Install resonators…
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      11-22-2022, 09:19 PM   #8
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Sounds like the turbos aren't spooling up.
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      11-23-2022, 08:08 AM   #9
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I've noticed it makes the noise when the wastegate hits 90% to spool up the turbo.

Doesn't do the noise in neutral

Here's a log: https://datazap.me/u/jluds/v10-n54-135i?log=0&data=3-20
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      11-23-2022, 05:20 PM   #10
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Quote:
Originally Posted by JLUDS View Post
I've noticed it makes the noise when the wastegate hits 90% to spool up the turbo.

Doesn't do the noise in neutral

Here's a log: https://datazap.me/u/jluds/v10-n54-135i?log=0&data=3-20
I don't see anything horrible in this log. HPFP is getting a little low for a second at high RPM (1500psi) and your AFRs bank to bank are kinda way off imo. Almost a whole unit apart.
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