I'm new to this game, so the noise I've got on my 2008 2.5 WRX, is something I can't understand. The intake between the intercooler & the manifold passes through a unit (?) that emits a sound like a household fan slowing down when the engine is switched off, sort of a few clicks & whistles. Can't hear it with the bonnet closed, however, when up can . No noise etc when running. Is it a viscouse fan or some such? And what does the noise mean?

I know this is a simple question to regular hands, to me its a puzzler.

Anyone help?

JohnJohnayreltd@aol.com

 

it helps emmisions on start up

 

its the tgv (tumble generator valve) as buster said its for emissions and does make this noise on start up

 

Thanks for that,

Sorry to be slow, makes this noise on switch off as well?

John