Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Please note that it is not permitted to have referral links posted in your signature. Keep these links contained in the appropriate forum. Thank you.

https://www.boards.ie/discussion/2055940817/signature-rules
Help Keep Boards Alive. Support us by going ad free today. See here: https://subscriptions.boards.ie/

NCT: Emissions failure

  • 17-10-2016 05:11PM
    #1
    Registered Users, Registered Users 2 Posts: 66 ✭✭


    Hi All,

    I've recently put a 05 Mazda 6 (1.8) through the NCT its passed everything except emissions. Any ideas where to start?
    Will fuel additives help or are these numbers way off?

    Here's the results I got.

    Exhaust Emissions:
    Engine/Oil temp: 94 °C

    Low Idle (700 rpm)
    CO 0.38 vol% (Limit 0.5%) Pass
    HC 392 ppm Result = N/A

    High Idle (2,640 rpm)
    Lambda: 1.18 (Pass Range: 0.97 to 1.03) Fail
    CO: 0.66 vol% ( Limit 0.3%) Fail
    HC 309 ppm (Limit 200 ppm) Fail

    Thanks in advance for any advice.


«1

Comments

  • Registered Users, Registered Users 2, Paid Member Posts: 5,202 ✭✭✭blackbox


    The HC and CO are high, but not massively so. This says it is running too rich. The high lambda also says running too rich.

    Worst case is that engine is worn and you are burning a lot of oil. You will know this by the need for frequent top-ups and/or blue smoke, especially when starting up. Don't worry too much about small puff of smoke just as it starts.

    Other possible reasons for running rich are
      restricted air flow - has the air filter been changed in the last year?
    • Dirty or faulty MAF.
    • Faulty Oxygen sensor (lambda probe).

    A worn cat is a possibility, but your readings would probably be worse if that was the case.
    After this you are getting into fairly unlikely scenarios...


  • Registered Users, Registered Users 2 Posts: 67 ✭✭Pa994


    Half a bottle of Dipetane and an Italian tune up :D


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    blackbox wrote: »
    The HC and CO are high, but not massively so. This says it is running too rich. The high lambda also says running too rich.

    Worst case is that engine is worn and you are burning a lot of oil. You will know this by the need for frequent top-ups and/or blue smoke, especially when starting up. Don't worry too much about small puff of smoke just as it starts.

    Other possible reasons for running rich are
      restricted air flow - has the air filter been changed in the last year?
    • Dirty or faulty MAF.
    • Faulty Oxygen sensor (lambda probe).

    A worn cat is a possibility, but your readings would probably be worse if that was the case.
    After this you are getting into fairly unlikely scenarios...

    Thank you very much for the reply. It was running for a week or so with little to no oil while my wife had it, so I have a feeling and really hope the engine is not damaged.


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    Pa994 wrote: »
    Half a bottle of Dipetane and an Italian tune up :D

    Yes I have read about this, I have the NCT again on Friday, I was thinking I should just use this to get past the NCT then get the car fixed properly.

    Would doing this get me passed? Ive read you need to high rev the engine to clear it out?


  • Registered Users, Registered Users 2 Posts: 22,575 ✭✭✭✭Steve


    Take the lambda sensor out and clean if if you can, seems to be running rich and would bet this is the cause.


  • Advertisement
  • Registered Users, Registered Users 2 Posts: 1,430 ✭✭✭Ciano35


    A lamda of over 1 suggests it's running lean doesn't it?


  • Registered Users, Registered Users 2 Posts: 67 ✭✭Pa994


    Do what Steve suggested if at all possible and then run Dipetane for a few days, its 50/50 whether it will work but will have only cost you €35 if it does, if it doesn't will be time to look at other things


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    Pa994 wrote: »
    Do what Steve suggested if at all possible and then run Dipetane for a few days, its 50/50 whether it will work but will have only cost you €35 if it does, if it doesn't will be time to look at other things

    Ok thanks guys, ill give that a shot. Have done some research and looked at a few youtube videos and it does not look too hard to find the o2 sensor and remove it.

    Regarding the Diperane, is it just a matter of adding half a bottle and running it for a day or two? Will the car need to be rev'ed up or driven more than to the shops to clear it out?


  • Registered Users, Registered Users 2 Posts: 5,163 ✭✭✭Mech1


    30 miles or so, and drive it like you stole it!


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    Mech1 wrote: »
    30 miles or so, and drive it like you stole it!

    Perfect, will try that, NCT is on Friday so will put it in tonight and should get 30km by then.
    Thanks


  • Advertisement
  • Closed Accounts Posts: 8,539 ✭✭✭jca


    Perfect, will try that, NCT is on Friday so will put it in tonight and should get 30km by then.
    Thanks

    Really? And you think adding snake oil and driving the ****e out of an engine that has been run low on oil is going to "fix" it. Any chance you might actually follow some logic like getting it serviced, well, at least change the oil and filter, check the spark plugs and air filter?


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    jca wrote: »
    Really? And you think adding snake oil and driving the ****e out of an engine that has been run low on oil is going to "fix" it. Any chance you might actually follow some logic like getting it serviced, well, at least change the oil and filter, check the spark plugs and air filter?

    No need to be like that!

    I will be getting it fixed, its actually up with the mechanic at the moment only his machine for detecting whats wrong is not working.

    I have to get the NCT done within a week so might as well try using this "snake oil" and if it fails it fails. Believe me, I understand that this isnt going to fix the issue!!!!!

    Thanks for your comment


  • Closed Accounts Posts: 8,539 ✭✭✭jca


    No need to be like that!

    I will be getting it fixed, its actually up with the mechanic at the moment only his machine for detecting whats wrong is not working.

    I have to get the NCT done within a week so might as well try using this "snake oil" and if it fails it fails. Believe me, I understand that this isnt going to fix the issue!!!!!

    Thanks for your comment

    Sorry for being ratty but adding stuff to fuel and Italian tune up suggestions gets on my wick. Could you reschedule the retest until the mechanic gets it fixed?


  • Closed Accounts Posts: 7,540 ✭✭✭Special Circumstances


    In my completely amateur opinion I also think there is more wrong with this engine than a bottle of dipetane and drive it like you stole it will cure.

    The actual emissions showing it running very rich, or on some type of two-stroke mixture, despite lambda showing lean, coupled with having been run low on oil...

    I'd love to hear the outcome if you get a chance to come back to us afterwards sausagekayak.


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    jca wrote: »
    Sorry for being ratty but adding stuff to fuel and Italian tune up suggestions gets on my wick. Could you reschedule the retest until the mechanic gets it fixed?

    I would love to reschedule it but they have told me it needs to be retested by Friday otherwise its back to a full test.
    Its probably going to fail again and will be a full retest giving me a few weeks to fix it.
    I understand where you are coming from, really, this isn't something I would normally do but I don't have time so I though I might as well try the fuel additive. It will be interesting to see if the numbers change.

    The car is still scheduled to go back to the mechanic next week either way so I will be getting it fixed.


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    In my completely amateur opinion I also think there is more wrong with this engine than a bottle of dipetane and drive it like you stole it will cure.

    The actual emissions showing it running very rich, or on some type of two-stroke mixture, despite lambda showing lean, coupled with having been run low on oil...

    I'd love to hear the outcome if you get a chance to come back to us afterwards sausagekayak.


    Yea sure, ill keep you guys updated!


  • Closed Accounts Posts: 8,539 ✭✭✭jca


    Yea sure, ill keep you guys updated!

    Please do. Out of curiosity more than anything else. Maybe your mechanic will find something handy, faulty pcv, blocked air filter etc and it turns out to be a cheap fix.


  • Posts: 1,659 ✭✭✭ [Deleted User]


    With the high lambda it's probably drawing unmetered air from somewhere like a displaced/leaky vacuum line, a clamp or inlet manifold gasket. You should listen for sucking sounds near the inlet manifold when the engine is idling.


  • Registered Users, Registered Users 2 Posts: 1,016 ✭✭✭Four Phucs Ache


    Hi,

    One of my workmates failed nct on emmisions on the same model car you have but 03

    New cat was needed....honeycomb inside had broken down.


  • Registered Users, Registered Users 2 Posts: 67 ✭✭Pa994


    jca wrote: »
    Sorry for being ratty but adding stuff to fuel and Italian tune up suggestions gets on my wick. Could you reschedule the retest until the mechanic gets it fixed?

    There is no point in putting a new cat or having something like piston rings done if its not necessary? €35 vs €435


  • Advertisement
  • Closed Accounts Posts: 8,539 ✭✭✭jca


    Pa994 wrote: »
    There is no point in putting a new cat or having something like piston rings done if its not necessary? €35 vs €435

    If snake oil fixes it, it doesn't need rings or a cat. A friend of mine had a vintage vauxhall with a clapped out crankshaft, he kept putting in Slick 50 to quieten the knocking big ends..... it worked because a connecting rod punched a hole in the block, it was quiet then.


  • Posts: 1,659 ✭✭✭ [Deleted User]


    Hi,

    One of my workmates failed nct on emmisions on the same model car you have but 03

    New cat was needed....honeycomb inside had broken down.

    The OPs problem is the lambda not at 1.00 though. Nothing points to a broken cat yet. Fitting a new cat to a car with lambda not at 1.00 is total waste of money unless there is actually a hole in the exhaust system at the cat.


  • Registered Users, Registered Users 2 Posts: 67 ✭✭Pa994


    jca wrote: »
    If snake oil fixes it, it doesn't need rings or a cat. A friend of mine had a vintage vauxhall with a clapped out crankshaft, he kept putting in Slick 50 to quieten the knocking big ends..... it worked because a connecting rod punched a hole in the block, it was quiet then.

    I've put a car through test and it failed miserably on emissions, put half bottle of dipetane to full tank and drove it about 100 miles went back through test perfectly. Snake oil? If it's been ran with no oil it's f**ked anyway least this will get it through test


  • Registered Users, Registered Users 2, Paid Member Posts: 5,202 ✭✭✭blackbox


    Ciano35 wrote: »
    A lambda of over 1 suggests it's running lean doesn't it?

    You are correct Ciano35 - I got this backwards.


  • Registered Users, Registered Users 2 Posts: 7,522 ✭✭✭kona


    A leaky exhaust somewhere would be my bet. I'd be looking aft of the first lambda.


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    Pa994 wrote: »
    I've put a car through test and it failed miserably on emissions, put half bottle of dipetane to full tank and drove it about 100 miles went back through test perfectly. Snake oil? If it's been ran with no oil it's f**ked anyway least this will get it through test

    Whats the ratio of petrol to dipetane I should put in?


  • Registered Users, Registered Users 2 Posts: 66 ✭✭sausagekayak


    Pa994 wrote: »
    I've put a car through test and it failed miserably on emissions, put half bottle of dipetane to full tank and drove it about 100 miles went back through test perfectly. Snake oil? If it's been ran with no oil it's f**ked anyway least this will get it through test

    ok just read your comment again correctly, you had a full tank and half a bottle of dipetane :-)


  • Closed Accounts Posts: 1,283 ✭✭✭...And Justice


    I'm sitting here in the nct centre now, car failed for emissions last time, changed the oxygen sensor and filled the tank with diptaine and petrol, hope it passes, there was some difference in performance after the oxygen sensor was changed out.


  • Closed Accounts Posts: 1,283 ✭✭✭...And Justice


    Failed on emissions again on high idle CO 0.26% above 0.20% how do I fix this, I've changed out the oxygen sensor and put diptaine in the fuel tank, what else do I need to do.

    Originally it failed for HC above 200ppm (220ppm) and CO.36% above 0.20%


  • Advertisement
  • Posts: 1,659 ✭✭✭ [Deleted User]


    Dipetane is a scam. --- You left out the most important number, i.e. the lambda value at high idle. Last time there was a really big excess of oxygen suggesting a leak somewhere.


Advertisement