hissing petrol cap and lumpy idle

[g60leigh]

A bit of a grumble this one.
On top of the airbox is a little valve. When i have it connected i have lumpy idle and can hear hissing from the fuel cap. If i disconnect it, it runs fine. I have been told it links to a charcoal filter and is something to do with fuel vapour purging. Does anyone know if it is needed? Should i replace the valve or leave it disconnected? ( while it is connected if you hit it it works ok for a short while)

 

[Broken Byzan]

I have the same, i repalced the valve and its good now

 

[g60leigh]

how much did it cost you? (and the stupid question- what is the part called?)
Thanks

 

[Broken Byzan]

N80 or purge valve £46.75 plus VAT from VAG parts

 

[AUDI TURBO]

anyone got a picture of this im sure my aeb 1996 a4 doesnt have this valve

 

[g60leigh]

mine definately does

 

[Broken Byzan]

 

[g60leigh]

thats the bit but mine is situtated on the top of the air box (Under a plastic cover)

 

[Broken Byzan]

I dont have the cover is all. keeps the heat in too much IMO,lol

 

[olds_kool]

i snapped this bit the other day changing air filter, was wondering what it did as car seems ok without it, should i replace it straight away or can it wait a couple of weeks?