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    Posted by Peter Wright on April 22, 2004, 4:58 am, in reply to "PLEASE SOMEONE COMMENT ON THE IGNITION SIDE OF THINGS"

    I gather you are measurinmg down stream of the cat - correct???

    If so HC's at 196?? are too high and this plus the Lambda and O2 readings indicate a misfire.

    An injector misfire (on MPI systems) will cause a slight change in HCs - can be slightly up or down as will be CO

    An ignition misfire will cause a very steep rise in HCs eg. above 2000 but CO will not be showing lean

    A misfire caused by an engine mechanical problem will bring about a rise in HCs but normally limited to about 1200 or so and once again CO will not be showing lean

    An overall lean misfire will show similar readings to what you are getting but I'd expect the HCs to be higher ahead of the cat.

    All these reading I talk about are taken upstream of the cat.

    The problem is the cat can mask problems. Ie. a CO showing lean could be just the cat doing its job but it your 196 HC, O2 and Lambda that show there is a problem

    HTH

    Peter Wright

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