2.4 v6 idle hunting and hissing from petrol filler cap

Oily Fingers

Registered User
Joined
Mar 18, 2011
Messages
4
Reaction score
0
Points
1
Location
NULL
hello, firsat post i know, but just been busy with a few things as of late and will get a proper build thread on the go soon.

But first, my 1998 a4 avant 2.4 v6 has a weird problem, when the car is running there is a constant hissing from the petrol filler cap, and for a short time after i have turned the car off. I have tried replacing the cap for a new one bu still the same??

second thign is, when on idle, the idle will stay fine for a while then rev the engine and as it comes back down to idle it will hunt and nearly stall. Have cut out a few times as well when slowing down to say roundabouts when i dip the clutch.
Am i right in thinking is will be more then likely the idle speed control valve??? or a vacuum pipe leaking??
When its hunting, i can put my foot very lightly on the throttle pedal and feel that moving up and down abit.

any help will be awsome!!!!!
joel