N54 Exhaust Low Pitched "Farting Sound"

SixSix · 05-01-2020, 10:22 PM

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.

ky0u · 05-02-2020, 09:23 PM

Does it only happen when shifting?

SixSix · 05-02-2020, 09:29 PM

Quote:

Originally Posted by ky0u

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

SixSix · 05-02-2020, 09:48 PM

Normal Exhaust Note

Low Pitched Exhaust Note

Vish8895 · 11-22-2022, 10:50 AM

Quote:

Originally Posted by SixSix

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?

JLUDS · 11-22-2022, 10:51 AM

Hi,

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

Driving me mad

Thank you

Dave92N54 · 11-22-2022, 07:51 PM

Uh, just sounds like a loud raspy N54 to me?

Install resonators…

zomski101 · 11-22-2022, 09:19 PM

Sounds like the turbos aren't spooling up.

JLUDS · 11-23-2022, 08:08 AM

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

Dave92N54 · 11-23-2022, 05:20 PM

Quote:

Originally Posted by JLUDS

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.

05-01-2020, 10:22 PM	#1
SixSix Private 20 Rep 91 Posts Drives: (2007 BMW 335i E92) Join Date: Oct 2019 Location: Toronto, ON iTrader: (0) Garage List 2002 BMW 325xi [0.00] 2007 BMW 335i [0.00]	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
ky0u Captain 1067 Rep 953 Posts Drives: e92 335i, f22 m235i, e30 325is Join Date: Sep 2010 Location: San Diego iTrader: (1) Garage List 2015 BMW M235i [0.00] 1988 BMW 325IS [0.00] 2007 BMW 335i [0.00]	Does it only happen when shifting?
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05-02-2020, 09:48 PM	#4
SixSix Private 20 Rep 91 Posts Drives: (2007 BMW 335i E92) Join Date: Oct 2019 Location: Toronto, ON iTrader: (0) Garage List 2002 BMW 325xi [0.00] 2007 BMW 335i [0.00]	Normal Exhaust Note Low Pitched Exhaust Note
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11-22-2022, 10:51 AM	#6
JLUDS New Member 2 Rep 10 Posts Drives: BMW 135i DCT Join Date: Apr 2015 Location: MIDLANDS iTrader: (0)	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
Dave92N54 Major 538 Rep 1,173 Posts Drives: 09 E92 335i 6MT Join Date: Nov 2020 Location: Westminster, Maryland iTrader: (0) Garage List 2009 BMW 335i [10.00]	Uh, just sounds like a loud raspy N54 to me? Install resonators… __________________ 09 E92 335i 6MT / Alpine White / Coral Red / VRSF 7.5" / VRSF DCI / VRSF Catless Downpipes / VTT Charge Pipe / Turbosmart RacePort Gen V / RB OEM Billet Turbos / CD919 Custom Tune / Bilstein PSS9s
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11-22-2022, 09:19 PM	#8
zomski101 Banned 56 Rep 147 Posts Drives: 2009 BMW 335i Join Date: May 2018 Location: Chicago, IL iTrader: (0)	Sounds like the turbos aren't spooling up.
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11-23-2022, 08:08 AM	#9
JLUDS New Member 2 Rep 10 Posts Drives: BMW 135i DCT Join Date: Apr 2015 Location: MIDLANDS iTrader: (0)	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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