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I'm desparate!MOT emission failed,could anyone tell me what these figures suggest

alexyuen999 Feb 24, 2014

  1. alexyuen999

    alexyuen999 New Member

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    Big thank you to you guys who could help or suggest.

    2001 facelift Audi S3 8L with 210bhp AMK engine. The ECU was hard chipped by the previous owner and cannot be reverted (I don't know anything more than this on this matter).

    Failed MOT due to high emission. I have read previous threads on this subject advising a few actions to begin with; I have cleaned the 2 cats and the pre-cat lambda sensors, to bring cat temp. up before testing etc... Readings improved slightly (to about 3.5 of CO) but still well over.

    here are the readings:

    CO at idle 4.090 %Vol
    CO at high idle 4.540 %Vol
    Lambda 0.871
    HC 0.00 ppm Vol

    From the threads I have read and some research on the web, I suspect it's too rich in combustion, could anyone with knowledge in this area help to determine what's causing this high level of CO emission please?

    Is it the old school chipping of the ECU or different sensor faults etc... One mechanic told me it might be cause by damaged injectors, which worries me a lot.

    Much appreciated.
     
  2. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

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    Any fault codes?

    <tuffty/>
     
  3. alexyuen999

    alexyuen999 New Member

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    Thanks tuffy, I don't have any equipment to check fault codes, and I haven't brought it to anyone who does. It might be stupid to say, but I haven't had a single warning light since I bought it a year ago, does it help?
     
  4. jojo

    jojo Looking for Boost! Staff Member Moderator Team Daytona Audi S3 quattro Audi A6 Audi Avant Owner Group

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    Where are you based?
     
  5. alexyuen999

    alexyuen999 New Member

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    Hi Jo Jo, I'm based in surrey. Thx.
     
  6. jojo

    jojo Looking for Boost! Staff Member Moderator Team Daytona Audi S3 quattro Audi A6 Audi Avant Owner Group

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    Bit too far for me to help you out Alex, but someone else may help you in the area?
     
  7. alexyuen999

    alexyuen999 New Member

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    I appreciate that jojo. What could you have done to help? If I know what to focus on, maybe I could act on it accordingly or find a specialist in that direction.

    Maybe I will locate a tuning place to look at fault codes if this is the first thing to do.

    Thanks again jojo.
     
  8. MSSD

    MSSD New Member

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    Where in surrey are you. I'm in horsham and have a diag tool.

    Might be as silly as a hole in the exhaust or oxygen sensor.
     
  9. Broken Byzan

    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User quattro Audi A4

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    it's running rich as hell according to that lambda figure 0f .0871.

    Can you be sure the cats are working as there is no real way to "clean them" that will make them magically work again
     
  10. AJC

    AJC 3rd Gear

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    Had same problem with MOT. Have VCDS if you want to check for fault codes and I'm in Surrey if that helps.

    Mine turned out to be a small hole in the post cat lambda sensor. Exhaust paste worked to get through MOT before a replacement cat arrived.
     
  11. alexyuen999

    alexyuen999 New Member

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    Thank you guys for your inputs. So a good place to start is on the lambda sensors? Pre or post cat would you guys suggest?

    How do I find out if the cats are working as it should be?

    Thank you everybody.
     
  12. alexyuen999

    alexyuen999 New Member

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    Hi guys, I have managed to vagcom the car and there are no fault codes at all. And I was told it's most likely to be one of the below:

    1. The ECU chipping which lead to massive fuel injection
    2. A dead catalytic converters

    I might try to find a 2nd hand ECU (original), and see if this would cure the problem. Any thoughts or suggestions on this?

    Thanks again everybody and I appreciate any comments.
     
  13. hades-

    hades- Well-Known Member VCDS Map User

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    have the cats been gutted ?
    its got a map so could have been de cat'ed
     
  14. IrishDave

    IrishDave Active Member

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    You need a new cat.
     
  15. alexyuen999

    alexyuen999 New Member

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    Hi Benz, and thanks. The original twin cat is there. It's not a remap on the ECU, it was an old school replacement chip soldered onto the ECU, and that's all I know sadly... I will probably try to look on eBay for a used one, I hope to get a cheap one to be honest.

    Thank you very much again man.
     
  16. alexyuen999

    alexyuen999 New Member

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    Thanks Dave, so it's not the chipped ECU you reckon? Cheers.
     
  17. Lavis89

    Lavis89 Well-Known Member Regional Rep Team Sprint Audi S4 Audi A3

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    I dont think it's quite so simple as a quick swap of the ECU, pretty sure you need to then get it coded to the car
     
  18. hades-

    hades- Well-Known Member VCDS Map User

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    you really need to get it logged
    before you go wasting cash trying to solve the problem
     
  19. alexyuen999

    alexyuen999 New Member

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    Yes Lavis, you are right, I have researched on it and I need to find someone to code it to my car. But this would be my best bet in getting it right and hopefully pass many MOTs to come. If that doesn't work, I will try replacing the cats as my last resort. Any positive or negative feedbacks are welcome.

    Thank you again Lavis
     
  20. alexyuen999

    alexyuen999 New Member

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    Hi Benz, what's getting it logged? Thanks
     
  21. hades-

    hades- Well-Known Member VCDS Map User

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    someone with vcds could do it for you
    how long has the chip been fitted ?cos if its been there a few years and passed its mot's then i would rule it out
    also when i asked about the cat gutted !
    the cat is still there but the innards taked out that could be the problem aswell
     
  22. <tuffty/>

    <tuffty/> Badger 5 Edition...Its all about the flow... Staff Member Moderator Audi S3

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    Need to read the fault codes in the first instance dude

    One thing to check though is the fuel pressure regulator... the rubber fuel hoses have a habit of rotting internally... the resultant rubber residue can accumulate in the FPR causing the fuel pressure to artificially rise... this can lead to the engine running too rich if its bad enough that it exceeds the ECU's ability to compensate
    Fuel system too rich fault code? see inside, it might be this - SEAT Cupra.net - SEAT Forum

    Info on getting hold of the software and logging etc can be found here
    http://www.audi-sport.net/vb/a3-s3-...-help-please-read-before-posting-updated.html

    <tuffty/>
     

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