Vacuum leak and rough idle


Registered User
Hi all,

Hoping someone might be able to help. I have an s3 8p 2008 and noticed last few days when idling the revs hunt between 800 and 1500. There's a loud hissing from the front of the engine bay and as soon as I take the oil cap off hissing stops. Guessing a vacuum leak from a split hose but curious how easy it is to get to that area behind the rad from below as I can't access it from above. Any help would be massively appreciated as I'm stuck in Italy for the next two months and would rather not take it to an italian garage as my italians shocking! Thanks in advance.

Paul @ Unit 9 Remaps

Registered User
Where are you based' we are north east and can do a boost leak test


Registered User
I have a very similar issue to this.
Does anyone know exactly what it is ?

I've been told it's a inlet diaphragm that needs replacing
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