1st Gen R53 Cooper S Most liked posts in thread: Running Rich... I wish it was money

  1. BlwnAway

    BlwnAway Well-Known Member

    Nov 24, 2011
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    15% shouldn't cause you to run rich, first I would find someone to clear your adaptations so that the ecu has a chance to learn the new pulley from scratch, if that doesn't do it, more likely it is actually the O2 sensor itself.
     
  2. Thumper460

    Thumper460 Active Member

    May 26, 2009
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    United States Navy ..Retired
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    Yep, what he said!! the pulley would more than likely 'lean' out a bit, do to the add'l boost.
    Could be now you are having a detonation issue and the knock sensor is doing what it was intended to do.. add fuel to save the engine! ( remember to drop a heat range on your spark plugs, when adding boost)
    Could be the MAP sensor!
    Could be the O2 sensor!

    Some one for sure will be on here to get deeper into this.

    Just me...............................

    Thumper

    PS: colder spark plug is the Autolite APP3923 and gap it at .035
     
  3. BlwnAway

    BlwnAway Well-Known Member

    Nov 24, 2011
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    Yup, forgot to ask if you did a pulley or a pulley kit.

    Or

    NGK BKR7EIX (also 1 step colder)