Strange rushing noise mk 2 digifant

[E105]

This is a bit of an odd one but when its under load and accelerating even lightly I get a rushing noise not quite a hiss but abit like that.  I dont think this is normal.  Almost like a very regular pre ignition noise.  Though I thought the knock sensor was supposed to sort out ignition timing.  I dont think its a vacuum leak but I do have a cold start problem, needs a good boot on the throttle then it starts and settles.

can the knock sensor be tested?

Any ideas on the noise?

[Overseer]

sounds like a vacuum leak..

[E105]

OK ill go through the induction system and check again

[Veedubgt18v]

check inbetween the pleats on the air hose to the throttle body as well these are often missed

[rubjonny]

Check the vacuum pipe behind the dash which feeds the MFA readout on the dash too.

[E105]

OK solved this one now, was a combination of an overtight cambelt and slight blow from the exhaust, and no i didnt fit the cambelt.

Cheers for all your help.