D-Sport engine bay Vacuum Pipes

[X5-D-Sport]

D-Sport engine bay Vacuum Pipes.

I bought some new 3mm ID silicone pipe to replace all the under bonnet tubing...

There is a black chamber/reservoir about 1/2 pint sized that I believe is to keep the turbo doing what ever it does for longer after a bit of speed.

With the engine running, I disconnected the pipe at the engine end of this black reservoir chamber... and the exhaust note suddenly deepened & sounded amazing... the revvs remained unchanged, no smoke when revved... but the exhaust not sounded deep & throaty (no puns plz lol)

With the pipe open to atmosphere & nice noisy exhaust note, the engine ran smoothly & didn't shake or hunt, just the nice new sound...

So the question is.... what did the pipe disconnection actually do to achieve the throaty rumble exhaust note ?

I still have to replace the rest of the vacuum pipes, but I do like the rumbly engine sound..

How is this happening & what is causing the note change ?

Any clues Richard ?

[X5Sport]

Erm........I haven't a good clue to be honest.  Got me thinking though.  I don't know what it actually does, other than leave you with no power if you don't keep it connected.  It's a vacuum reservoir so must be changing the waste gate perhaps?

[X5-D-Sport]

if you can, unclip the pipe on the engine side of the vacuum reservoir & listen to the not change..

I've got a modified exhaust any way that is gently rumbley, and this pipe disconnection make an amazing noise difference..

As you correctly say, I drove her with the pipe disconnected, got a great exhaust note... but the power bled off to bugger-all lol 

[X5Sport]

I don't have anything like this on the X6....at least not that I have found yet!  There is probably some fiendishly expensive whatamathingy that does it in a way only BMW can do.... :blink:

[Horizon]

On the standard exhaust system there is a vacuum operated flap on my 330i in one of the duel exhaust exit pipes, it stays closed until the engine warms up I think. It's supposed to create more back pressure to increase torque when the engine is cold.
You can do the " Golf tee mod,"  which blocks off the vacuum to the valve makes it sound more throaty.
Maybe yours has a similar valve.
It's usually situated at the backbox

[X5-D-Sport]

Hi  Horizon...
This sounds very plausible, however.... I know for sure there is no flap on either back box, as I have had them both off previously..
Also there are no electrical connections to the exhaust system from the turbo charger backwards....(i think)

The throaty noise is certainly akin to the "flap" concept.... but no idea where it could be located.

Is there is any kind of schematic for the vacuum pipes & what they connect to ?

###Richard may be able to find this - pretty Please ?

Re the vacuum release causing the nice Chonky Rumble noise... I did check the vehicle exhaust smoke levels & I'm pretty sure it is nothing to do with fueling, as the engine runs / idles perfectly hot or cold...

Maybe there is a flap or something near or on the turbo charger some how..

I disconnected the air intake pipe from the grille to the air box, 7 it is possible to hear the waste gate hiss or turbo over-run after punching the throttle as the revvs die off, but it does this whether this little vac pipe is connected or not.

I think the answer will be found with a vac-pipe schematic layout for the E53 diesel engine...
Any one know how to find this please ?

Grant B