I replaced this part about two years ago as one of the connectors was broken, I asked what is was but no one seemed to know what it does at the dealers, I've noticed the engine stops revving properly at about 3000rpm and the engine management light comes on, when it revs at about 3200rpm the light goes out and the engine revs fine, it only does it under load, I had it looked at and it came back with a cam sensor problem so I replaced that, it didn’t help, if I had the thing in the picture connected wrong could that cause a problem?
http://www.elliott1077.com/4abd_1.jpg

It's the vacuum tank -

see http://www.omegaowners.com/forum/YaBB.pl?num=1152565204 and

http://www.omegaowners.com/forum/YaBB.pl?num=1153840176

for a bit more info.

Hth

Yup, confirmed, Vac tank.  One up by pollen filter, and one between bagpipes on most V6s (early ones only had 1 I believe)

TheBoy wrote on 27. Sep 2007 at 12:27:

one between bagpipes on most V6s (early ones only had 1 I believe)

Bagpipes sire!?! That would explain why your car has a troubled history, being scottish an all  ;D A short break in loch lomond required me thinks  ;)

wrote on 26. Sep 2007 at 23:33:

I asked what is was but no one seemed to know what it does at the dealers,

You'll find that happening a lot with Vauxhall dealers...

Yep, can confirm that early cars had just one vac tank near the pollen filter. :y

Weds wrote on 27. Sep 2007 at 18:29:

wrote on 26. Sep 2007 at 23:33: I asked what is was but no one seemed to know what it does at the dealers, You'll find that happening a lot with Vauxhall dealers...

Vx would most likely say it was a foo foo valve, I think Vx employ all renault mechanics, when I used to use Vx in Cardiff they were useless.