Why is my exhaust now louder?

dm2583 · 09-11-2017, 03:47 AM

So recently my car was with BMW and had a whole heap of work carried out to try ad fix a limp mode issue.

Since I've had the car back, the exhaust is now almost embarrassingly loud upon moderate/hard acceleration. Its a BMW Performance exhaust.

Any ideas why this could be? Some of the work I had carried out was:

-replacement of sparks, coils and injectors
-walnut blast
-new hpfp and smaller pump
-torque convertor replaceent
-new DME and FRM modules

Could any of this have affected it?

BMW335iSport · 09-11-2017, 03:55 AM

As I'm feeling generous I'm willing to swap my standard exhaust system for your performance exhaust, I'll take the burden of the louder exhaust off your hands out of the goodness of my heart.

dm2583 · 09-11-2017, 05:28 AM

hahahaha thats an awfully kind gesture

RENT-A-GOAT · 09-11-2017, 07:42 AM

Car was running rough so not the right pressures were going on to the exhaust system so noise was not generated as it should be now the running is sorted the pressures are right and your finally getting what you paid for in terms of the perf. exhaust. Don't worry just enjoy and if it's too loud change to standard and there will be a line if people to buy the perf. one of you.

Stop worrying and go enjoy your BM!

juld0zer · 09-11-2017, 08:40 AM

New FRM and DME requires programming and encoding. It's unusual for the exhaust to get louder after programming. I've only heard the opposite (except the F56 with JCW sport exhaust)

Andy198712 · 09-11-2017, 09:34 AM

They didn't tighten a clamp is my guess...

dm2583 · 09-11-2017, 11:57 AM

Quote:

Originally Posted by Andy198712

They didn't tighten a clamp is my guess...

I'm hoping its what RENT-A-GOAT says but i'm going to get the clamps checked just to be sure

ChawenHalo · 09-12-2017, 08:08 PM

Sounds like a leek somewhere.

McPikie · 09-13-2017, 03:53 AM

Quote:

Originally Posted by ChawenHalo

Sounds like a leek somewhere.

I'd think one of these in the exhaust would cause back pressure and quieten it down, no?

ChawenHalo · 09-13-2017, 05:39 AM

Quote:

Originally Posted by McPikie

I'd think one of these in the exhaust would cause back pressure and quieten it down, no?

I'm french therefore have an excuse for not eating my leaks.

TomD335xicoupe · 09-13-2017, 07:06 AM

What did the shop say when you brought it back and told them?

david in germany · 09-13-2017, 07:29 AM

Messing with Ista-p a while back, I did see a function in there once for retrofit sport exhaust. Could it be they just coded the car for the exhaust?

AWSAWS · 09-14-2017, 08:36 AM

It's probably just a different diameter and resonance pattern changing the sound.

I changed the cats on mine and it's far louder.

ChawenHalo · 09-14-2017, 03:58 PM

Quote:

Originally Posted by david in germany

Messing with Ista-p a while back, I did see a function in there once for retrofit sport exhaust. Could it be they just coded the car for the exhaust?

Presumably it enables the ECU to understand the change in backpressure from the new exhaust. Is it a full line or at least going to the cat in the middle or just backboxes?

david in germany · 09-14-2017, 04:01 PM

Quote:

Originally Posted by ChawenHalo

Presumably it enables the ECU to understand the change in backpressure from the new exhaust. Is it a full line or at least going to the cat in the middle or just backboxes?

That is what I was thinking. Most of the performance exhaust are cat back.

ChawenHalo · 09-16-2017, 05:48 PM

Quote:

Originally Posted by david in germany

That is what I was thinking. Most of the performance exhaust are cat back.

Yep. Its far cheaper that way. Simple, just see how much lighter a "performance" back box is compared to OEM - its just because they've removed sons deadening pathways and material.

There is rarely any gains in performance, especially for N/A cars. To get proper performance gains its a full line and headers and that's €7k min. That does not mean that the ECU won't know something is aloof and perhaps to do with the cat and the regent process.

Ask BMW if performance exhaust have to be "coded" in to the car. Perhaps a friendly dealership will let you know if they have that function on their software or installation procedure.

09-11-2017, 03:47 AM	#1
dm2583 Second Lieutenant 30 Rep 246 Posts Drives: E92 335i \| E36 M3 Join Date: Nov 2014 Location: Cotswolds iTrader: (0)	Why is my exhaust now louder? So recently my car was with BMW and had a whole heap of work carried out to try ad fix a limp mode issue. Since I've had the car back, the exhaust is now almost embarrassingly loud upon moderate/hard acceleration. Its a BMW Performance exhaust. Any ideas why this could be? Some of the work I had carried out was: -replacement of sparks, coils and injectors -walnut blast -new hpfp and smaller pump -torque convertor replaceent -new DME and FRM modules Could any of this have affected it?
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09-11-2017, 03:55 AM	#2
BMW335iSport Private 21 Rep 67 Posts Drives: Citreon Join Date: Jul 2017 Location: somewhere iTrader: (0)	As I'm feeling generous I'm willing to swap my standard exhaust system for your performance exhaust, I'll take the burden of the louder exhaust off your hands out of the goodness of my heart.
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09-11-2017, 05:28 AM	#3
dm2583 Second Lieutenant 30 Rep 246 Posts Drives: E92 335i \| E36 M3 Join Date: Nov 2014 Location: Cotswolds iTrader: (0)	hahahaha thats an awfully kind gesture
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09-11-2017, 07:42 AM	#4
RENT-A-GOAT Major 444 Rep 1,047 Posts Drives: F31 320D Xdrive Msport+ Join Date: Jun 2015 Location: Warwickshire iTrader: (0) Garage List 2015 BMW F31 320D X ... [0.00]	Car was running rough so not the right pressures were going on to the exhaust system so noise was not generated as it should be now the running is sorted the pressures are right and your finally getting what you paid for in terms of the perf. exhaust. Don't worry just enjoy and if it's too loud change to standard and there will be a line if people to buy the perf. one of you. Stop worrying and go enjoy your BM! __________________ [url=https://www.deutschespeed.com/threads/the-bimmerpost-refugee-thread.561/]Click here for the Bimmerpost UK Refugees - Censorship Sucks![/url]
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09-11-2017, 08:40 AM	#5
juld0zer Lieutenant Colonel 480 Rep 1,600 Posts Drives: Prev 135i 7DCT, Now 130i 6sp Join Date: Jul 2016 Location: 2153 iTrader: (0)	New FRM and DME requires programming and encoding. It's unusual for the exhaust to get louder after programming. I've only heard the opposite (except the F56 with JCW sport exhaust)
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09-11-2017, 09:34 AM	#6
Andy198712 Major 160 Rep 1,060 Posts Drives: 2010 E91 325d Join Date: Mar 2017 Location: Cornwall iTrader: (0)	They didn't tighten a clamp is my guess...
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09-12-2017, 08:08 PM	#8
ChawenHalo Second Lieutenant 68 Rep 286 Posts Drives: E91 330d XDrive LCI M Pack Join Date: Apr 2017 Location: Bordeaux iTrader: (0)	Sounds like a leek somewhere.
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09-13-2017, 07:06 AM	#11
TomD335xicoupe First Lieutenant 319 Rep 378 Posts Drives: 08 335XI me ,19 x3 M40 wife Join Date: Aug 2014 Location: North Jersey iTrader: (1)	What did the shop say when you brought it back and told them? __________________
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09-13-2017, 07:29 AM	#12
david in germany Lieutenant Colonel 735 Rep 1,819 Posts Drives: 118i, 335i and 328i Join Date: Nov 2011 Location: Mannheim Germany iTrader: (2)	Messing with Ista-p a while back, I did see a function in there once for retrofit sport exhaust. Could it be they just coded the car for the exhaust? __________________ 2009 118i Monaco Blue "Maximillion" 2009 335i Saphire Black M Sport "Leopold" Cobb stage 2 aggressive tune, Mishimoto FMIC, Cobb charge pipe, Cobb catted down pipes, Forge diverter valves, BMS inlets and DCI, Cyba scoops and M Individual Audio retrofit and M3 gauge cluster retrofit. 2011 328i Titan Silver M Sport "Franzel" <--Wife's car
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09-14-2017, 08:36 AM	#13
AWSAWS Colonel 279 Rep 2,340 Posts Drives: E92 GC Turbos, FBO, 335i DCT Join Date: Nov 2012 Location: Valhalla iTrader: (0)	It's probably just a different diameter and resonance pattern changing the sound. I changed the cats on mine and it's far louder. __________________ GC Turbos, FBO, JB4, DCT, Port Meth injection, BMS Charge Pipe, NGK plugs. EBC brakes and pads, LED Angel lights, LED foglights, LCI rears OCC, Braided brake lines. Custom Diff Lockdown Kit, VTT inlets, TMAP, stage 2+ fuel pump 11.79@119mph (stock turbos) 11.74@129mph (GC Turbos)
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