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    LDV Convoy 2002 2.0L-failed MOT emissions Archived Message

    Posted by Nick Bell on September 21, 2007, 9:57 am

    Gentlemen,
    Hope you can help me with this;

    Called in by garage to this van they've had a week, and now it's really urgent and needs sorting NOW (always the case by the time I'm called in!)
    I believe they've changed plugs, filters and oil and fitted a new Airflow Meter. Probably not relevant but has a gas conversion.

    Gas analysis
    CO 0.63
    HCs 120
    lambda 1.04
    O2 1.37
    CO2 14.34

    I 'scoped the O2 sensor and it is switching beautifully, slower at idle but certainly quicker than once a second (>1Hz) at fast idle, and very regular.

    Believe it's some sort of Ford (Transit?) engine and could get lots of believable live data under 2.0L Zetec. STFT seemed OK, dodging around 0%, but LTFT was -24% (may be historical?). Garage found a code P0172 (they tell me this means rich) but cleared and no codes while I was there. We sprayed around inlet man. to expose leaks but none found.

    Am I correct in thinking that oxygen in exhaust (and therefore fuelling) has got to be correct because of correct O2 switching, and extra O2 must be leaking in post O2 sensor!

    Can I rule out the CAT? I believe lambda would be correct even if CAT failing!?

    I know this type of problem has been discussed many times before but can I find posts now I need them?

    Any flaws in my reasoning please, or any help gratefully received!!

    Regards,
    Nick Bell

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