Weird 'siren' like sound coming from catless DPs....

cstmx_ryder · 08-05-2008, 04:32 PM

So when accelerating under 2k rpm, there's a whiny, siren-like sound coming from my catless DPs (it's not the sound of turbos spooling). I'm assuming it's coming from the catless DPs, as I have never encountered this sound/issue prior to installing the DPs.

The whine goes away after about 2.5k rpm.

Has anyone come across this issue? If so, please chime in......

Thanks

nj335i · 08-05-2008, 04:54 PM

Do you have an exhaust leak between the DPs and the rest of your exhaust?

cstmx_ryder · 08-05-2008, 04:57 PM

Quote:

Originally Posted by nj335i

Do you have an exhaust leak between the DPs and the rest of your exhaust?

well, good question.......Would that be the cause of the weird sound I'm hearing?

I don't think so, as I've seen the connection between the exhaust side of the DPs and the exhaust piping. They both seem tightly secured.

Thanks

scalbert · 08-05-2008, 05:05 PM

I would suspect an exhaust leak.

O-cha · 08-05-2008, 05:09 PM

Either an exhaust leak or the sound of the turbos, I have my money on the sound of the turbos.

Do you have exhaust or just the DP?

Riss Racing · 08-05-2008, 05:13 PM

Make sure the turbo clamps are tight. That is usually where that noise comes from.

joec500 · 08-05-2008, 05:14 PM

Quote:

Originally Posted by O-cha

Either an exhaust leak or the sound of the turbos, I have my money on the sound of the turbos.

Do you have exhaust or just the DP?

2nd....Deja Vu of my old B5 S4....sounded like a firetruck right before they croaked.

BavarianBeastTamer · 08-05-2008, 05:17 PM

Yeah when i hear a siren sound after going a hundred or so; i just speed up to about 135-140 and the sound goes away pretty quick. But sometimes i hear a chopper noise afterwards that you can only get rid of by driving through a parking garage or tunnel. Weird huh?

Check that everything is clamp down tight. like the other poster said

ironic · 08-05-2008, 05:19 PM

i vote leak

1clean335i · 08-05-2008, 05:37 PM

make sure the o2 sensors are tight too..

Mr. 5 · 08-05-2008, 05:42 PM

Quote:

Originally Posted by O-cha

Either an exhaust leak or the sound of the turbos, I have my money on the sound of the turbos.

Do you have exhaust or just the DP?

I really hope not, but I would put my money with yours.
An exhaust leak sounds like an exhaust leak.
It doesn't sound like a siren unless the turbos are on their way out.
no bueno.

O-cha · 08-05-2008, 06:13 PM

Quote:

Originally Posted by Mr. 5

I really hope not, but I would put my money with yours.
An exhaust leak sounds like an exhaust leak.
It doesn't sound like a siren unless the turbos are on their way out.
no bueno.

I don't agree that the siren sound is turbos on the way out, unless every car that has downpipes put on has turbos on the way out.

I think it has a lot to do with the decreased back pressure increasing the off idle spool of the turbos.

Mr. 5 · 08-05-2008, 06:26 PM

Quote:

Originally Posted by O-cha

I don't agree that the siren sound is turbos on the way out, unless every car that has downpipes put on has turbos on the way out.

I think it has a lot to do with the decreased back pressure increasing the off idle spool of the turbos.

I think we're talking about 2 different siren sounds.
I consider my sound to be a whistle but I guess someone can hear it differently like a siren.

I was thinking aobut the youtube vid that serisouly sounded like a siren.

scalbert · 08-05-2008, 08:55 PM

If it sounds like a dentist's drill, the turbo lady is calling. ;

Those coming from turbo Audi's will remember the sweet lady:

e90AW335i · 08-05-2008, 08:56 PM

Quote:

Originally Posted by scalbert

If it sounds like a dentist's drill, the turbo lady is calling. ;

Those coming from turbo Audi's will remember the sweet lady:

Nice one Steve....

Does anyone have the link to that video that has that sound in it. I want to know that sound just in case....

08-05-2008, 04:32 PM	#1
cstmx_ryder Colonel 171 Rep 2,875 Posts Drives: A metal box with a roundel Join Date: Jul 2007 Location: Portland, OR iTrader: (2)	Weird 'siren' like sound coming from catless DPs.... So when accelerating under 2k rpm, there's a whiny, siren-like sound coming from my catless DPs (it's not the sound of turbos spooling). I'm assuming it's coming from the catless DPs, as I have never encountered this sound/issue prior to installing the DPs. The whine goes away after about 2.5k rpm. Has anyone come across this issue? If so, please chime in...... Thanks __________________ '08 AW E90 335i PROcede V5 \| BMS DCI \| RR DPs \| ETS FMIC \| FORGE DVs \| Stett CP \| Vanguard \| PSS10
	Appreciate 0 Tweet Quote

08-05-2008, 04:54 PM	#2
nj335i Modaholic 95 Rep 1,707 Posts Drives: with 3 pedals Join Date: Jan 2007 Location: East Coast iTrader: (7)	Do you have an exhaust leak between the DPs and the rest of your exhaust? __________________ Euro Delivery - April 2007
	Appreciate 0 Quote

08-05-2008, 05:05 PM	#4
scalbert Major General 158 Rep 5,776 Posts Drives: '13 S4, '15 Q7 Join Date: Feb 2007 Location: Woodstock, GA iTrader: (8)	I would suspect an exhaust leak.
	Appreciate 0 Quote

08-05-2008, 05:09 PM	#5
O-cha Brigadier General 230 Rep 4,726 Posts Drives: Mcoupe Join Date: Oct 2007 Location: In front of you iTrader: (2)	Either an exhaust leak or the sound of the turbos, I have my money on the sound of the turbos. Do you have exhaust or just the DP? __________________
	Appreciate 0 Quote

08-05-2008, 05:13 PM	#6
Riss Racing Banned 278 Rep 2,650 Posts Drives: E60 M5/E92 335/HUMMER H2 Join Date: Jun 2007 Location: Irvine, CA iTrader: (7)	Make sure the turbo clamps are tight. That is usually where that noise comes from.
	Appreciate 0 Quote

08-05-2008, 05:17 PM	#8
BavarianBeastTamer Second Lieutenant 22 Rep 219 Posts Drives: 550i m4 vert on order Join Date: Jun 2008 Location: Hoboken iTrader: (0)	solution is to speed up Yeah when i hear a siren sound after going a hundred or so; i just speed up to about 135-140 and the sound goes away pretty quick. But sometimes i hear a chopper noise afterwards that you can only get rid of by driving through a parking garage or tunnel. Weird huh? Check that everything is clamp down tight. like the other poster said
	Appreciate 0 Quote

08-05-2008, 05:19 PM	#9
ironic Major General 269 Rep 8,338 Posts Drives: Jet Black 335i Join Date: Dec 2006 Location: San Francisco, Ca iTrader: (22)	i vote leak __________________ Widebody 335i Project Car BUILD \| PHOTOSHOOT
	Appreciate 0 Quote

08-05-2008, 05:37 PM	#10
1clean335i Perf BMW mag issue 147, 159 432 Rep 6,799 Posts Drives: Project Estoril Join Date: Feb 2007 Location: Miami, FL iTrader: (31) Garage List 2013 335i M-sport [0.00] 2011 X5 xdrive35i M ... [0.00] 2009 335i M-sport [0.00] 07' 335i Sedan [0.00]	make sure the o2 sensors are tight too.. __________________ '13 Estoril Blue 335i M-sport *Don't PM me!* Message me here- http://www.facebook.com/ProjectEstoril
	Appreciate 0 Quote

08-05-2008, 08:55 PM	#14
scalbert Major General 158 Rep 5,776 Posts Drives: '13 S4, '15 Q7 Join Date: Feb 2007 Location: Woodstock, GA iTrader: (8)	If it sounds like a dentist's drill, the turbo lady is calling. ; Those coming from turbo Audi's will remember the sweet lady:
	Appreciate 0 Quote