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Oxygen/Lambda sensor on two stroke

  1. Jun 25, 2010 #1
    I have a two stroke Yamaha motorcycle and I wish to fit a narrow band lambda sensor to the exhaust with the intention of monitoring air/fuel ratios and eventually designing and making a simple closed loop fuel injection system (with some open loop capabilities, until the sensor warms up or at full power).
    I have most of the equipment I need e.g an analogue oscilloscope (digital storage scope would be better but oh well), prototyping boards, access to components and electronics experience including an A level in electronics.
    My question is how do you think the lambda sensor would cope with two stroke exhaust gasses?

    According to wiki:
    "The sensor does not actually measure oxygen concentration, but rather the amount of oxygen needed to completely oxidize any remaining combustibles in the exhaust gas. Rich mixture causes an oxygen demand. This demand causes a voltage to build up, due to transportation of oxygen ions through the sensor layer. Lean mixture causes low voltage, since there is an oxygen excess."

    So would the raw fuel that passes through the exhaust port during gas the exchange on a two stroke and the extra hydrocarbons from un-burnt two stroke oil affect the operation and readings of a lambda sensor to the point that it is unable to determine if the engine is actually running lean or rich?

    Thank you very much
  2. jcsd
  3. Jun 25, 2010 #2

    Ranger Mike

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    i think you ould be better off putting a exhaust temperature sensor on the header and monitoring the temp for optimum mixture..read the spark plugs because when you monkey with the fuel air ration you can lean out the mix and burn a piston..
  4. Jun 25, 2010 #3
    Thank you for your reply, measuring EGT is very good idea I will adopt (as a way of double checking for leaned mixture) however it wouldn't give the accuracy and response I would be looking for as a feedback for my fuel injection project.
    I have been thinking of dropping the narrow band sensor in favour for a wide band but these sensors are rarer and more expensive, however a wider range sensor can read a larger range of air/fuel ratios and a linear output sothe ability to compensate for errors due to un-burnt fuel etc would be easier.
    I will fit a tempurature sensor to the exhaust next week to get a feel for what are normal tempuratures for my bike at various loads and rpms and make a note of these.
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