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Thread: Emissions

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    SSOC Junior RedDevil's Avatar
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    Emissions

    Hi guys and Gals....I've just had my 2009 swift sport MOT'd and have found the emissions are higher than last year. They have gradually increased every year since I've owned the car but my usual trips have always been short ones. However, I have just done over a thousands miles last week and thought that the car having such a good run (500 miles each way) that the emissions would have been really low this time......wrong, they were even
    higher than last year.

    Anyone got any ideas as to why this might be? Would appreciate any comments.

    Many thanks.

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    SSOC Lover hoikey's Avatar
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    Any mods? Cats generally will become less efficient as time goes on, the lambda sensor may need a clean, do you use super unleaded? Also the warmer the engine the lower they tend to be

    Sent from my SM-G900F using Tapatalk

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    Quote Originally Posted by hoikey View Post
    Any mods? Cats generally will become less efficient as time goes on, the lambda sensor may need a clean, do you use super unleaded? Also the warmer the engine the lower they tend to be

    Sent from my SM-G900F using Tapatalk
    S/S exhaust from cat back but only done a few months ago, lambda sensor makes sense though, never thought of that, also spark plugs have never been renewed but only 40k on clock at moment and don't know if the plugs would affect it anyway. I don't fill up with super unleaded very often but should have the last time, just forgot about MOT being due!

    Many thanks for your reply, much appreciated.

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    SSOC Lover hoikey's Avatar
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    The spark plugs should have been done if the cars 6 years old

    Sent from my SM-G900F using Tapatalk

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    SSOC Junior carlosvalderrama's Avatar
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    It'll be a couple of issues.

    Cats degrade over time, the platinum and other catalyst metals which are loaded onto the surface of the cat are lost out of the exhaust, and are also 'saturated' as the catalytic reduction process can lead to the permanent chemical reaction of a proportion of the catalysts. This isn't preventable, although continuous cold running will accelerate it due to the richer mixture used on a cold engine.

    A second reason could be the change in exhaust structure. The running pressure in the exhaust system downstream of the cat will have reduced, this has the effect of causing the cylinder to evacuate the combustion gases faster than before. If the ignition mapping or valve timing hasn't been changed, this means that the gases are leaving earlier in the combustion cycle, which means more HC emissions. HC through the cat is similar to constant cold running where the mixture will be over-rich. This leads to the same earlier degradation of the cat.

    The second reason is only a possible cause, as it depnds on how the exhaust was designed. The further from the head that the pressure is reduced, the less impact it has.

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    SSOC Lover hoikey's Avatar
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    Out of interest your cat back exhaust, does it still have the second cat?

    Sent from my SM-G900F using Tapatalk

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    SSOC Junior RedDevil's Avatar
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    Quote Originally Posted by hoikey View Post
    The spark plugs should have been done if the cars 6 years old

    Sent from my SM-G900F using Tapatalk
    I wondered about the plugs but thought they were changed around 60k, thanks, will get them done.

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    Quote Originally Posted by hoikey View Post
    Out of interest your cat back exhaust, does it still have the second cat?

    Sent from my SM-G900F using Tapatalk
    Yeah, it was done from the 2nd cat, they changed the design though, instead of having the horizontal back box they put 2 single back boxes on, had to take it back a couple of times as the system was banging on the underneath of the car.

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