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MOT Fail on Lamda and fast idle test (so close!)

Discussion in 'A4/S4 forum(B5 Chassis)' started by jcb, Apr 4, 2012.

  1. jcb
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    jcb Active Member VCDS Map User

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    [Apr 4, 2012]
    OK so its an A6 2.8 but no-one lives over there so I am asking here!

    MOT at Kwikfit (yes I know, first mistake but they are £20 cheaper than anyone else so the retest is basically free!)

    Lambda and CO failed but so unbelievably close to the limit!!

    0.022 on lambda first fast idle
    0.001 on lambda on second fast idle!

    0.030 and 0.044% over on CO on fast idle tests

    I have a small leak just before the CAT, that wouldn't change anything would it?
    Going to log Lambda measuring blocks and voltage now and swap the plugs out

    [​IMG]

    any suggestions?
    its very minor
    #1
  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 4, 2012]
    any exhaust leaks can effect lambda reading and cause a rich mixture, so get some gun gum round the small leak if you can to seal it up

    Then give it absolute death for 10 mins and get it back to kwikfit with it red hot for another test.

    The cats look tired though, unless they were cold?

    The guy often holds the RPM's up around 3k for a good couple of minutes if it fails to get some heat into the cats, did they do that?
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  3. jcb
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    jcb Active Member VCDS Map User

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    [Apr 4, 2012]
    no, its KwikFit!
    the only think they are interested is selling other ****
    £4.99 for a sidelight bulb? "no thanks I get my own cheers"

    am on the exhaust leak and it was only really present when revving so possible.
    pulled 4 out of 6 plugs and they looked fine, bit of a coating but nicely brown and dry

    probably needs new ones anyway so will do that and get it back asap
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  4. Mackers
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    Mackers Member

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    [Apr 4, 2012]
    as above, seal ya exhaust (it would effect the emmisions) ya could try fuel treatment, or as also stated, give it "an itailian tune" and blast and keep it running when there so it's RED HOT. :D
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  5. jcb
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    jcb Active Member VCDS Map User

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    [Apr 4, 2012]
    would an inlet vacuum leak cause this?
    The Lambda is showing its lean right?
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 4, 2012]
    very slightly lean yeh.
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  7. jcb
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    jcb Active Member VCDS Map User

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    [Apr 4, 2012]
    just replaced all the horrible fabric covered hoses around the in inlet with some nice silicon I had.

    next the exhaust leak

    not doing plugs, cant be arsed and they look pretty good as it is.

    finger crossed
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  8. murran
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    murran Active Member

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    [Apr 4, 2012]
    id say that exhaust leak is causing the lambdas to see a weak mixture when there isnt one.
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  9. jcb
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    jcb Active Member VCDS Map User

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    [Apr 5, 2012]
    am seriously struggling to stop the exhaust leak.

    smothered in gun gum, wrapped in exhaust bandage and under load even after hardening it has blown through a tiny amount again.

    there must be some serious back pressure in front of the CAT

    Anyone know of any super strong exhaust bodge?!
    #9
  10. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 5, 2012]
    Weld? :p
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  11. jcb
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    jcb Active Member VCDS Map User

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    [Apr 5, 2012]
    yeah that is what worries me.
    it is right up front right next to the hanger. its a front pipe out job if it is welded!

    cant see a fecking thing on these engines.
    is a front pipe removal an engine out job on a V6 like every other engine out job!?
    #11
  12. murran
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    murran Active Member

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    [Apr 5, 2012]
    is this a 2.8 30v v6? no its not an engine out job. is it the 2 flexible bits infront of the cats that are blowing? a decent exhaust place can remove the front pipes and weld in new flexible sections. only danger is one of the three manifold studs snapping off.
    ive done a couple of these at work. much cheaper than new cats!
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  13. jcb
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    jcb Active Member VCDS Map User

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    [Apr 10, 2012]
    Woo Hoo!!

    repair on the exhaust, a new CTS and some sidelights! MOT passed.
    now for the painful experience of taxing a 2.8!
    Last edited: Apr 10, 2012
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  14. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 10, 2012]
    Shouldnt be any more expensive than the 1.8T if its pre-2001...
    #14
  15. jcb
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    jcb Active Member VCDS Map User

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    [Apr 10, 2012]
    ha, try £240!
    #15
  16. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Apr 10, 2012]
    Yep, 1.8T is the same!
    #16

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