1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

1.8T - hissing from fuel cap?

Discussion in 'A4/S4 forum(B5 Chassis)' started by niggtv, Mar 19, 2006.

  1. niggtv
    Offline

    niggtv Member

    Joined:
    Mar 7, 2006
    Messages:
    81
    Likes Received:
    2
    Hi,

    I have noticed that when the engine is running there is a loud hissing coming from the petrol cap on my 1997 A4 Avant 1.8T.

    If I push the filler cap in the hissing stops, but then the idle on the car drops and it doesnt tick over smoothly.

    I have tried swapping the petrol cap itself incase this was all that was worng, but that didnt solve it.

    One last thing, the car seems to be very slightly hesitant - I had thought this might be the MAF, but am wondering if it linked to this problem somehow.

    Any ideas guys? Cheers
    #1
  2. madvw
    Offline

    madvw Active Member

    Joined:
    Jul 26, 2005
    Messages:
    2,488
    Likes Received:
    2
    probably will be. Most of them will show the check engine light if it detects a leak here. The vapor from the tank is now recirculated, rather than vented into the atmosphere.

    you say you've tried swapping the petrol cap, was it for a new oem one, or a replacement get you home jobbie?
    #2
  3. niggtv
    Offline

    niggtv Member

    Joined:
    Mar 7, 2006
    Messages:
    81
    Likes Received:
    2
    I replaced it with the fuel cap from my mate's A4... they looked exactly the same.
    #3
  4. madvw
    Offline

    madvw Active Member

    Joined:
    Jul 26, 2005
    Messages:
    2,488
    Likes Received:
    2
    strange. It sound like there may be too much pressure then.

    Does anybody know if the petrol caps have valves in? If so, what regulates the pressure in the fuel tank recirc?
    #4
  5. Kevint
    Offline

    Kevint Active Member

    Joined:
    Jun 19, 2003
    Messages:
    1,182
    Likes Received:
    0
    I had a similar problem on an Astra once. The car would stall every now and then though.

    It turned out to be a blocked vent pipe which was connected to the neck of the fuel filler.

    Kev.
    #5
  6. niggtv
    Offline

    niggtv Member

    Joined:
    Mar 7, 2006
    Messages:
    81
    Likes Received:
    2
    Cheers, sounds like it might be something like a vent pipe.

    Has anyone had this hissing problem on an Audi, or suggest any other possible causes?
    #6
  7. niggtv
    Offline

    niggtv Member

    Joined:
    Mar 7, 2006
    Messages:
    81
    Likes Received:
    2
    Well, thought I would post up the solution incase anyone else ever has the same problem. It was the recirculation/solenoid valve, which is located near the airbox in the engine bay. Part number is 058 133 517.
    #7
  8. Daveiow
    Offline

    Daveiow Member

    Joined:
    May 3, 2006
    Messages:
    264
    Likes Received:
    0
    did it sort out teh car being hesitant as well ????
    #8

Share This Page