Boom noise on gear change with DSG

sb272 · Post by **sb272** » Fri Sep 09, 2011 11:06 pm

Hi - first thread on here for me!

I have recently bought an R and have noticed an odd noise most noticeable on high rpm up changes.

It sounds like a bassey boom and is starting to annoy me.

I'm wondering if it's caused by the flap valve in the silencer reacting and causing the noise but found some footage of a manual R accelerating hard and there was no noise like my DSG car makes. I'm assuming both cars have standard back box.

I've also noticed odd bass noises as I change throttle position, lifting off slightly from a constant throttle.

Another thought is that the noise is some sort of blow off valve or dump valve bleeding off boost when changing gear or when lifting. I have another car with forced induction and have a blow off valve fitted and just let the excess boost vent to atmosphere rather than reaching back into the pre-turbo induction system and so it's acting like a dump valve. The boom from the R sounds nothing like the other car's blow off valve and appear to be coming from the rear and I would expect any blow off valve will be fitted under the bonnet.

Please could someone please explain this DSG up change noise, why it happens and how to get rid of it as it is spoiling an otherwise brilliant car!

Thanks, Steve.

chani1312 · Post by **chani1312** » Fri Sep 09, 2011 11:45 pm

Think you bought the wrong car 4 yourself dude

sb272 · Post by **sb272** » Fri Sep 09, 2011 11:54 pm

chani1312 wrote:Think you bought the wrong car 4 yourself dude

Why?

kenti · Post by **kenti** » Sat Sep 10, 2011 12:44 am

Does these "boom noise" appear then shifting down?

Shaun · Post by **Shaun** » Sat Sep 10, 2011 5:54 am

sb272 wrote:
chani1312 wrote:Think you bought the wrong car 4 yourself dude
Why?

I Think he means you bought a sporty car and are now complaining that it sounds sporty ?, the noise on gearchange sounds like the DSG Fart you get when up changing, it's quite normal and the video you watched was either a manual car/ or broken or not an R or he wasnt trying hard enough.
[youtube][/youtube]
[youtube][/youtube]

If that's the noise then it's just a DSG thing (when booted) , it can be heard on this golf also.

[youtube][/youtube]

jonallen628 · Post by **jonallen628** » Sat Sep 10, 2011 7:18 am

The 2.0 TSI DSG makes this noise as well, but it is far more agressive in the R which personally is one of the things I love about the car. Lots of cars make this noise, including some manual ones normally on lift off. My old Renaultsport Clio 197 used to do it too. VW have engineered a little character into a sporty car, how rude :-). Bad news is if you really don't like it and it annoys you then better change your car as it is 100% normal.

langley182 · Post by **langley182** » Sat Sep 10, 2011 9:19 am

chani1312 wrote:Think you bought the wrong car 4 yourself dude

X2

It's the DSG Fart you're on about pal. Completely normal when changing up.
What's not to love? Sounds awesome, especially with a decat

sb272 · Post by **sb272** » Sat Sep 10, 2011 11:12 pm

Thanks for the replies.

If what I have is the DSG fart noise, why can't I hear it on on these videos?

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Or

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I've owned many a sporty car and know what they should sound like and the noise mine is making isn't right or sporty sounding! My Impreza doesn't do it, my Wife's Abarth 500 didn't and they are both turbo cars. My supercharged and turbocharged 300bhp Elise doesn't either but it does make a racket P-sssting the excess boost during gear changes and sounds proper sporty (ignoring the excessive boost dumping which needs recircing back into the induction)!

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I'm starting to wonder if I have a fault with the boost recirc in my R or if the previous owner has fitted some aftermarket dump or blowoff valve. I don't remember hearing the bass/fart noise when test driving a dealer's R and GT DSG Sciroccos.

My boom/fart noise is most apparent when boost is high and I don't get it if I manually go up and down the box when cruising on light throttle. I sometimes hear the noise on down changes.

Shaun · Post by **Shaun** » Sun Sep 11, 2011 5:38 am

So are you saying the videos i posted are wrong ?, i can post hundreds of DSG equiped cars that do the same, You have posted videos of cars that don't make the noise that a DSG R should make when upchanging, for whatever reason they are wrong or the mic on the camcorder didnt catch the noise, a DSG fart on the R at high RPM is quite normal, is what your experiencing the same as the videos I have posted ?, you have not answered that yet ?.

Post some pictures of the engine bay, the original dump valve sits At the front of the engine not far the bonnet lock and should be black, is yours silver ?, do you have the standard exhaust and downpipe and cay ?, finally if you think it's broken take it to the dealers ?.

Is this the noise that your talking about ?, or something entirely different.

[youtube][/youtube]

sb272 · Post by **sb272** » Sun Sep 11, 2011 11:29 am

Thanks Shaun. You've posted no internal videos so I can't say if yours are right or wrong compared to what I hear from inside my car. I've not heard what mine sounds like from outside so can't say if it sounds like the cars in your vids.

I've spent more time on YouTube and all the internal recorded DSG R videos don't have the noise I'm hearing but it could be too low a frequency for mics to pick up.

As far as I know the car is standard, rear silencer certainly is. The seller never mentioned that anything was modified. I'll take a look under the bonnet at the wastegate.

I'll try and record something later and upload to YouTube.

Can anyone confirm if the exhaust flap valve changes briefly when a high rpm gear change happens?

Shaun · Post by **Shaun** » Sun Sep 11, 2011 11:55 am

Is the Exhaust flap connected ?, PS the flap is not causing the DSG burp.

Shaun · Post by **Shaun** » Sun Sep 11, 2011 12:14 pm

The sound inside is like that from outside videos only a bit less

Not brillant video but you can just about make out the 'Fart'
[youtube][/youtube]

langley182 · Post by **langley182** » Sun Sep 11, 2011 4:44 pm

All petrol turbo charged cars with a DSG box will 'fart' on the upshift. Fact.
More noticeable under heavier acceleration.
There is essentially no break in drive to the wheels when changing gear.
You imagine the DSG is changing between the two clutches in around 8 milliseconds, the engine will have no opportunity to rev freely like it would in a manual car when you press the clutch in.
For example, Within the space of 8 milliseconds the engines speed is dragged from 5500rpm down to 2800rpm with the upshift. Factor in this quick rpm change, fueling and the ecu tweaking the throttle position regardless of your foot position and you are gonna get an interesting fart noise from the exhaust.
Stop being paranoid, your car is not broken.

sb272 · Post by **sb272** » Sun Sep 11, 2011 11:21 pm

Like you say I can just make out the boom in the vid above.

My concern is that the boom is sometimes very loud, like there is a large subwoofer in the boot. If the noise was low level like it appears in the vid then fine but it is very boomy and loud. But the volume is by no means consistent or always related to throttle position or direction of change.

I believe my flap valve is connected and opening/closing as at about 3800-3900rpm the exhaust note changes and gets a little louder. But I wonder if it is behaving itself correctly.

As well as the gear change boom, I'm also getting very deep bass booms whilst holding the same gear but changing throttle position slightly, eg lifting slightly to match speed of a car in front. These booms are quite subtle compared to the gear change noise but I see no reason at all for them being made.

I took a friend out tonight who happens to be an automotive engineer (currently working at Nissan Tech Centre) and he's done a bit of noise work in his time and although he's had no direct experience with DSG his gut feel was that my car wasn't "right" so I'll be popping along to the stealers this week for an opinion and also a quick trip out in one of their demo cars with DSG.

If there are any R owners who live near or near-ish to Oxford I'd appreciate a trip out in another car, as I don't think my local dealer has an R in stock to try?

RW1 · Post by **RW1** » Mon Sep 12, 2011 6:54 am

sb272 wrote:My concern is that the boom is sometimes very loud, like there is a large subwoofer in the boot. If the noise was low level like it appears in the vid then fine but it is very boomy and loud. But the volume is by no means consistent or always related to throttle position or direction of change.

While mine isn't an R, I get this boom effect, particularly when the engine is warming up in the first three minutes and then it goes gradually quieter after that. Fuelling is rich while the engine is very cold. By the time the engine is hot, its minmal or nothing. Always occurs when the throttle is pressed harder and the engine is dropping significant RPM in a DSG up gear change. Put down to what langley182 has written above.

C.

Post by **Kev** » Mon Sep 12, 2011 8:15 am

I also don't have an R but I love the 'fart'. It seems to vary depending on how much welly it's being given.

I live in Oxford. I'm happy to come and listen to your farts

sb272 · Post by **sb272** » Mon Sep 12, 2011 8:46 am

Thanks Kev, I'll send you a PM.

RW1, interesting that yours get quieter once warmed up.

RW1 · Post by **RW1** » Mon Sep 12, 2011 9:16 am

sb272 wrote:RW1, interesting that yours get quieter once warmed up.

Wouldn't read anything into that! Different engine, different fuelling, different gears ratios, different exhaust - different resonance. Just a characteristic of DSG sharply dropping the engine rpm down at gear change.

Just drive and enjoy!

C.

sb272 · Post by **sb272** » Mon Sep 12, 2011 9:32 am

I do enjoy it

sb272 · Post by **sb272** » Tue Sep 13, 2011 9:53 pm

sb272 wrote:I do enjoy it

As Kev will testify after I took him out for a compare and contrast with a GT DSG

(1mph lower than wigit on his "test" btw).

Whilst you could hear the boom in Kev's car it was very hard to hear compared to my car. I know the R has a different rear silencer. Is the mid resonator and/or the downpipe different also?

Does anyone have any pics of the downpipe on the R please? I will get under mine and see what it looks like to determine if it isn't standard. I've seen a pic of the resonator posted somewhere so can find that again.

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