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

Failed MOT on emissions, need advice please

Discussion in 'A3/S3 Forum (8L Chassis)' started by Dubstep, Nov 12, 2012.

  1. Dubstep
    Offline

    Dubstep Member

    Joined:
    Jun 6, 2011
    Messages:
    54
    Likes Received:
    1
    [Nov 12, 2012]
    Hi, so my car went for its mot today and failed on its emissions. Ive had the car sorn'd for the past year while ive done some work on it.
    here are my Emission results:

    Fast Idle:
    CO = 1.24 - fail
    HC = 759 - fail
    Lambda = 0.988 -pass

    Second Fast Idle:
    CO = 1.17 -fail
    HC = 296 -fail
    Lambda = 1.146 - fail

    Natural Idle:
    CO = 1.50 - fail


    The car is modded with SS mani, 3" dp, 200 cell cat and jetex exhaust. Ive connected to a VC and no faults are coming up.

    How can i reduce these figures?
    #1
  2. Ads

    Ads

    [Sep 22, 2014]

  3. aragorn
    Online

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,576
    Likes Received:
    314
    [Nov 12, 2012]
    The figures are higher than you would expect with no cat at all on a healthy engine, so i'd suggest you need to be looking at fuelling/sensors.

    Might be lambda or MAF, or a air leak throwing out adaption?

    Have a look at the fuel trims with VCDS.
    #2
  4. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,336
    Likes Received:
    697
    [Nov 12, 2012]
    ecu can only control its lambda....
    #3
  5. Dubstep
    Offline

    Dubstep Member

    Joined:
    Jun 6, 2011
    Messages:
    54
    Likes Received:
    1
    [Nov 12, 2012]
    Ok, so ive got a brought some things to try and fix my issue:
    Plugs
    Fuel filter
    Wynns Clean burn

    Should i be looking at getting a new lambda sensor (apy so only have 1 sensor)?
    Also ive noticed that it might be running rich as the mpg is bad and there is a faint smell of fuel in the engine bay when engine running, would putting the original airbox back on then restrict the amount of air therefore lowering the ratio?
    #4
  6. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,336
    Likes Received:
    697
    [Nov 12, 2012]
    do you have vagcom to check lambda readings
    #5
  7. Dubstep
    Offline

    Dubstep Member

    Joined:
    Jun 6, 2011
    Messages:
    54
    Likes Received:
    1
    [Nov 12, 2012]
    no :-( only a cheap vc to read/wipe codes
    #6
  8. AJC
    Online

    AJC 3rd Gear

    Joined:
    Jan 2, 2008
    Messages:
    173
    Likes Received:
    8
    [Nov 12, 2012]
    I've had exactly the same problem with the MOT last week. I'm about to connect up VCDS to check for fault codes but think I might need a new lambda sensor. Any way to check Bill if this needs to be replaced?
    #7

Share This Page