Black box under engine cover

Gaz7

Active Member
Jun 13, 2014
385
0
Directly on top of the rocker cover, covers coil packs 3+4 ? That's the vacuum chamber
 

Gaz7

Active Member
Jun 13, 2014
385
0
I think mine is flapping around in the wind, I'm sure it's supposed to have a fixing though. Its associated with the n249 valve, an ecu controlled valve for cutting boost if it needs to, it's like a safeguard against n75 failure as far as I understand. The chamber holds vacuum so the valve can open the dump valve when no vacuum is being created at the inlet. As far as I'm aware.
 

myfirstseat

Active Member
Apr 11, 2015
109
1
Perth, Scotland
That's alright then, do you not have an engine cover? Im sure it shouldn't be doing any flapping?? I thought the LC's and LCR's had a fully recirculating valve?
 

Gaz7

Active Member
Jun 13, 2014
385
0
Probably not, not a major issue though, just a bolt that hasn't been put back at some point. Yes they are recirc valves, the boost pressure still has to go somewhere when the throttle gets closed, it gets vented into the charge pipe.
 

dazjstuart

Active Member
May 18, 2012
660
8
Aberdeen
Just get rid of it, its not required, the engine can still shut down the boost if it's overboosting without the N249. its supposed to be for that and for faster recirc valve response when you lift off the throttle but it doesn't work like that. Many people find boost is smoother and more consistent if they bypass or delete the N249 and the chamber. What you can do is remove the chamber and blank the pipes going to it, then plumb the recirc valve into a different vacuum source (fuel pressure regulator usually). You can also do a full delete of the valve and pipework too but that's a little more complicated mechanically, plenty of guides on here and other VAG sites though.
 

myfirstseat

Active Member
Apr 11, 2015
109
1
Perth, Scotland
Thanks for the advice. Where is the fuel pressure regulator? Do you have a picture, i dont know much about this under bonnet stuff so im trying to pick stuff up as i go along.
 
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