Question on a "hoo" sound after going Stage 2 BM3

FallenRainDrops · 02-22-2019, 12:34 AM

Hello, just a question:

I had a local (tuning) shop a few weeks ago install a VRSF FMIC and VRSF Chargepipe on my BMW 435i. When I went home, I flashed Stage 2 Octane 93 AGG.
I went cruising with some buddies and I drove pretty hard, and afterwards I noticed whenever I'm driving and give it a lil hard rev and let go, I hear a "HOO" sound, like an owl.
This sound comes after hearing the turbo spool and letting go of the gas.
I don't get that sound at low RPM's.
I never got this sound before when I was running stock OEM parts..

Not sure if I have a boost leak or damaged something, or possibly something to do with my intake? Any ideas?

Eschmacher · 02-22-2019, 01:33 AM

That's your diverter valve, everything is probably fine. You didn't hear any of this before because you're running way more boost on stage 2.

It's possible the extra boost has killed your diverter valve and it's leaking, but you would need to log the boost with bootmod to tell.

Marlinman · 02-22-2019, 07:52 AM

^^ This. However I will tell you mine makes that slight noise and I am PS2 with upgraded DV valve so it could be normal. Logs are best as stated before.

FallenRainDrops · 02-22-2019, 09:51 AM

Okay thx!! Ill check it out

XxThe_RemedyXx · 02-22-2019, 10:03 AM

I heard the same sound when I first had my catless DP installed. No issues so far knock wood and it's been on the car for months now. For me, I believe it's the less restrictive pipe allowing more air to flow. Things will naturally get louder as you're increasing power and remove the restriction.

Bluebeasty · 02-22-2019, 02:31 PM

Perhaps your buddies are flatulent......

FallenRainDrops · 02-22-2019, 05:05 PM

I asked one of my good buddies and he said thus is normal too lol.
Thx again everyone

Shayan55 · 03-01-2019, 03:21 PM

I would get a log and see whats going on it you are really concerned, you may need to upgrade your DV

kevinjt · 03-01-2019, 07:17 PM

Normal! mine does it as well, i have the CTW intake and it kind of amplifies that sound.

02-22-2019, 12:34 AM	#1
FallenRainDrops Enlisted Member 12 Rep 37 Posts Drives: '14 435i RWD Join Date: Aug 2018 Location: illinois iTrader: (0)	Question on a "hoo" sound after going Stage 2 BM3 Hello, just a question: I had a local (tuning) shop a few weeks ago install a VRSF FMIC and VRSF Chargepipe on my BMW 435i. When I went home, I flashed Stage 2 Octane 93 AGG. I went cruising with some buddies and I drove pretty hard, and afterwards I noticed whenever I'm driving and give it a lil hard rev and let go, I hear a "HOO" sound, like an owl. This sound comes after hearing the turbo spool and letting go of the gas. I don't get that sound at low RPM's. I never got this sound before when I was running stock OEM parts.. Not sure if I have a boost leak or damaged something, or possibly something to do with my intake? Any ideas? __________________ F32 2014 435i RWD Borla Atak full exhaust, Wagner catless DP, aFe intake, VRSF FMIC, VRSF Chargepipe, Bootmod3 stage2 Octane 93 (AGG) BC Racing Coilovers Last edited by FallenRainDrops; 02-22-2019 at 12:41 AM..
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02-22-2019, 01:33 AM	#2
Eschmacher Car Hypochondriac 335 Rep 901 Posts Drives: 2014 335i M-Sport Estoril Blue Join Date: Feb 2017 Location: Sterling, VA iTrader: (0) Garage List 2014 BMW 335i [0.00]	That's your diverter valve, everything is probably fine. You didn't hear any of this before because you're running way more boost on stage 2. It's possible the extra boost has killed your diverter valve and it's leaking, but you would need to log the boost with bootmod to tell. __________________ Power mods: VRSF IC/Catted DP - FTP CP/BP - AFE Cat-back - BM3/XHP - Dorch S2 Handling mods: Koni yellow - Eibach prokit - Millway street - M Performance LSD - M3 brakes - EBC bluestuff Exterior: Euro LCI tail lights - Shitty ECS CF spoiler - Chinese M performance diffuser Interior: Bavsound stage 1 and subs - custom trunk sub by Mike1327
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02-22-2019, 07:52 AM	#3
Marlinman First Lieutenant 101 Rep 316 Posts Drives: 2013 335i xDrive Join Date: Jun 2015 Location: MD iTrader: (0)	^^ This. However I will tell you mine makes that slight noise and I am PS2 with upgraded DV valve so it could be normal. Logs are best as stated before.
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02-22-2019, 09:51 AM	#4
FallenRainDrops Enlisted Member 12 Rep 37 Posts Drives: '14 435i RWD Join Date: Aug 2018 Location: illinois iTrader: (0)	Okay thx!! Ill check it out
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02-22-2019, 10:03 AM	#5
XxThe_RemedyXx Colonel 967 Rep 2,653 Posts Drives: 2016 340i xDrive Join Date: Aug 2009 Location: Westchester, NY iTrader: (0)	I heard the same sound when I first had my catless DP installed. No issues so far knock wood and it's been on the car for months now. For me, I believe it's the less restrictive pipe allowing more air to flow. Things will naturally get louder as you're increasing power and remove the restriction. __________________ 2016 340i xDrive - BM3 Stage 2 93 OTS - xHP Transmission Tune Stage 2 - B58TU HPFP - Bilstein B14 - VRSF Catless DP - Kyostar CAI
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02-22-2019, 02:31 PM	#6
Bluebeasty Private 77 Rep 66 Posts Drives: 2015 335i M sport FBO BM3 Join Date: Dec 2018 Location: Socal iTrader: (0)	Perhaps your buddies are flatulent......
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02-22-2019, 05:05 PM	#7
FallenRainDrops Enlisted Member 12 Rep 37 Posts Drives: '14 435i RWD Join Date: Aug 2018 Location: illinois iTrader: (0)	I asked one of my good buddies and he said thus is normal too lol. Thx again everyone
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03-01-2019, 03:21 PM	#8
Shayan55 Captain 339 Rep 716 Posts Drives: F90 M5 Join Date: Jun 2016 Location: woodland hills CA iTrader: (1) Garage List 2105 BMW M235I [0.00]	I would get a log and see whats going on it you are really concerned, you may need to upgrade your DV __________________ (Sold) M235I Dinan intake, Active Autowerke FMIC, meisterschaft, TCKline coilovers, NT01's, BMS Oil cooler valve, VRSF DP&CP, BM3,StopTech Trophy BBK, Corbeau FX1 Pro seats, AP bar, Bimmerworld V3 Wing, APR Front splitter, Seibon Vented CF Hood 399.8whp on 91oct Hmu on Ig: @n55_shayan
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03-01-2019, 07:17 PM	#9
kevinjt First Lieutenant 152 Rep 352 Posts Drives: 335i M-Sport 14' Join Date: May 2016 Location: Puerto Rico iTrader: (1)	Normal! mine does it as well, i have the CTW intake and it kind of amplifies that sound. __________________ __________________ 335i EB RWD \| ///M Sport Pkg \| BMS Intake \| M Performance Exhaust \| ER Catless Downpipe \| ER FMIC \| ER Charge pipe \| CF Aero \| 19" Black M4 Wheels \| Candy Orange ///M Brake Calipers \| ///M Steering wheel \| ///M Metal Pedals \| Euro Spec - LCI Taillights
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