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

Idle boost reading

Discussion in 'A3/S3 Forum (8L Chassis)' started by sekenzo, Oct 4, 2011.

  1. sekenzo
    Offline

    sekenzo Member

    Joined:
    Sep 26, 2009
    Messages:
    102
    Likes Received:
    0
    [Oct 4, 2011]
    Can someone confirm what is the normal idle vac reading? I am currently at -0.8 bar... Does this sound like I have a leak?
    #1
  2. Ads

    Ads

    [Dec 28, 2014]

  3. 16Klappe
    Offline

    16Klappe RacecaR forward is RacecaR backwards. Supporter

    Joined:
    Sep 16, 2008
    Messages:
    5,774
    Likes Received:
    1,140
    [Oct 4, 2011]
    Just checked, mine sits at -22PSI.
    #2
  4. s3gazz
    Offline

    s3gazz Well-Known Member

    Joined:
    Aug 11, 2010
    Messages:
    1,264
    Likes Received:
    65
    [Oct 5, 2011]
    Mine is -20
    #3
  5. sekenzo
    Offline

    sekenzo Member

    Joined:
    Sep 26, 2009
    Messages:
    102
    Likes Received:
    0
    [Oct 5, 2011]
    -0.8bar = -11.6 psi.. Sounds like something is wrong...
    #4
  6. DJ_Troopa
    Offline

    DJ_Troopa K1 Driver

    Joined:
    Oct 30, 2008
    Messages:
    1,743
    Likes Received:
    14
    [Oct 6, 2011]
    I'm on -13.4. I've also been told i have a boost leak but then i've been told everything is fine? Confused.com
    #5
  7. 16Klappe
    Offline

    16Klappe RacecaR forward is RacecaR backwards. Supporter

    Joined:
    Sep 16, 2008
    Messages:
    5,774
    Likes Received:
    1,140
    [Oct 6, 2011]
    To be fair because it is making negative pressure it will be difficult to tell if and where the boost leak is, you will need to have it vacuum and pressure tested.
    #6
  8. DaveA3
    Offline

    DaveA3 Audi A-Trizzle!

    Joined:
    Feb 25, 2010
    Messages:
    2,374
    Likes Received:
    14
    [Oct 6, 2011]
    -20 until i drive it a bit then it goes to -25 when i stop
    #7
  9. Andy123
    Offline

    Andy123 Member

    Joined:
    Jan 3, 2009
    Messages:
    260
    Likes Received:
    2
    [Oct 7, 2011]
    You want around 19/20 inHg of vacuum, anything much lower would suggest a leak. Not measured in psi by the way, -20psi isn't possible.
    #8
  10. Westy
    Offline

    Westy Double Dark Side! Diesel & 8P

    Joined:
    Dec 2, 2008
    Messages:
    17,348
    Likes Received:
    993
    [Oct 7, 2011]
    A lot of guages show hg in vacuum not PSI. mine is around -14hg
    #9
  11. S3 Paul
    Offline

    S3 Paul Well-Known Member Regional Rep

    Joined:
    Oct 27, 2006
    Messages:
    2,782
    Likes Received:
    73
    [Oct 7, 2011]
    I was beginning to think i had a problem... Mine has never seen -20 psi !
    I was told mine was "giving a good reading indicating no leaks or problems "
    I will check what it actualy reads later when i head out.
    #10
  12. Westy
    Offline

    Westy Double Dark Side! Diesel & 8P

    Joined:
    Dec 2, 2008
    Messages:
    17,348
    Likes Received:
    993
    [Oct 7, 2011]
    I'm sure this subject has come up before and around -13-14hg was about right :think:
    #11
  13. S3 Paul
    Offline

    S3 Paul Well-Known Member Regional Rep

    Joined:
    Oct 27, 2006
    Messages:
    2,782
    Likes Received:
    73
    [Oct 7, 2011]
    I was thinking high 'teens
    Different when still on cold start too?
    #12
  14. Westy
    Offline

    Westy Double Dark Side! Diesel & 8P

    Joined:
    Dec 2, 2008
    Messages:
    17,348
    Likes Received:
    993
    [Oct 7, 2011]
    This is mine on cold start then it drops a bit when warm:

    [​IMG]
    #13
  15. s3gazz
    Offline

    s3gazz Well-Known Member

    Joined:
    Aug 11, 2010
    Messages:
    1,264
    Likes Received:
    65
    [Oct 7, 2011]
    When mine starts (cold) it's 12 psi ish then when warmed it goes to 20 psi
    #14
  16. Sandip
    Offline

    Sandip Well-Known Member

    Joined:
    Nov 7, 2006
    Messages:
    2,400
    Likes Received:
    65
    [Oct 7, 2011]
    Mine is -20 in.Hg

    Looking at most boost gauges

    Vacuum - in.Hg

    Boost (positive pressure) - PSI
    #15
  17. s3dave
    Offline

    s3dave TFSI Hybrid Supporter

    Joined:
    Nov 11, 2009
    Messages:
    10,120
    Likes Received:
    729
    [Oct 7, 2011]
    It all depends on the calibration of the guages i mean pay 20 quid for a guage you are hardly going to have lab results.....
    Andy123 is correct, it is shown in HG not psi and all the forced induction cars ive had, it has always shown around the 20 in hg mark on idle, infact i used to use this as a tool if it went closer to 10 in hg, i new i had a leak somewhere, and sure enough there was one...:o.k:
    #16
  18. Dani_B19
    Offline

    Dani_B19 Audi-sports own special child.

    Joined:
    Nov 9, 2008
    Messages:
    7,304
    Likes Received:
    91
    [Oct 7, 2011]
    Mines around the 20 mark.
    #17
  19. hades-
    Offline

    hades- Yorkshire & Humber Rep. Regional Rep VCDS Map User

    Joined:
    Jul 8, 2008
    Messages:
    9,078
    Likes Received:
    558
  20. S3 Paul
    Offline

    S3 Paul Well-Known Member Regional Rep

    Joined:
    Oct 27, 2006
    Messages:
    2,782
    Likes Received:
    73
    [Oct 8, 2011]
    Mine sits at about -18 once warm, Goes up ( or down ) to -22 on over run,
    #19

Share This Page