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NCT Emissions - is this possible?

  • 07-06-2010 05:31PM
    #1
    zilog_jones
    Registered Users, Registered Users 2 Posts: 6,638 ✭✭✭


    Got my car tested earlier today, but I thought the emissions results looked a bit odd:

    Temp: 91° C

    Low idle (1090 rpm) - CO 0.00%, HC 70 ppm

    High idle (2920 rpm) - Lambda 1.00, CO 0.00%, HC 108 ppm

    The car is a '98 Fiesta 1.3. HC stuff looks reasonable, but 0% CO? Is this even possible? Are they going easy on old cars? Though saying that there was a similarly aged Renault Scenic tested next to mine that failed on emissions.

    There's a problem with one of the valves so it doesn't idle very well at all (maybe misfiring), I was almost certain it would fail on emissions because of this (been like this for at least 3-4 years) but it's somehow improved since last time! Maybe I should not question these things... :D


Comments

  • #2
    L1011
    Registered Users, Registered Users 2 Posts: 72,400 ✭✭✭✭L1011


    The CO figure and testing procedure changes dependent on the cars age:
    RSA wrote:
    For vehicles first registered on or after 1st day of January1994,
    the carbon monoxide content at 2,500 rpm or at a speed
    specified by the vehicle manufacturer is more than 0.3%.

    It changes again for post '02 cars.

    Don't see how that'd cause an 0 reading so either it *did* have an 0 reading or the kit was faulty!


  • #3
    Mr.David
    Registered Users, Registered Users 2 Posts: 1,705 ✭✭✭Mr.David


    Why wouldn't it have a 0% reading?

    CO is carbon monoxide not dioxide as most of the COx molecules would be.


  • #4
    Mr Benevolent
    Closed Accounts Posts: 12,456 ✭✭✭✭Mr Benevolent


    Mr.David wrote: »
    Why wouldn't it have a 0% reading?

    CO is carbon monoxide not dioxide as most of the COx molecules would be.

    Bad idle/misfire = incomplete combustion = CO production imo.


  • #5
    zilog_jones
    Registered Users, Registered Users 2 Posts: 6,638 ✭✭✭zilog_jones


    Mr.David wrote: »
    Why wouldn't it have a 0% reading?

    CO is carbon monoxide not dioxide as most of the COx molecules would be.

    I know what CO is. I'm no chemist but I thought there'd always be at least some CO emissions. Surely the cat is not 100% efficient at converting CO, especially one that is possibly 12 years old? Even more so considering what Confab said. Previous NCTs have shown 0.01-0.02% CO.

    @MYOB: I'm aware of the different limits for different ages of car, I was just wondering if the testers (from personal experience maybe) are maybe more lenient with particular models of older cars known to have trouble passing on emissions.


  • #6
    L1011
    Registered Users, Registered Users 2 Posts: 72,400 ✭✭✭✭L1011


    There are exemptions from spec for certain cars. Do you have an old Rover or Suzuki Cultus?

    Even if so I'd expect the number to appear on the cert...


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  • #7
    Max_Damage
    Closed Accounts Posts: 5,461 ✭✭✭Max_Damage


    The low idle CO emission on my Escort (same 1.3L pushrod engine as zilog's) was 0.02% at the last NCT in November.


  • #8
    Chazz Reinhold
    Registered Users, Registered Users 2 Posts: 50 ✭✭Chazz Reinhold


    Failed mine over the weekend on both low and high idle
    Low Idle: CO 1.57 vol% anything above 0.50% is a fail
    HC 103ppm anything above 0ppm is a fail

    High Idle: Lambda 0.88 between 0.97 and 1.03 is a fail
    CO 4.41 vol% anything above 0.30% is a fail
    HC 272ppm anything above 200ppm is a fail

    Any ideas?


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