Hi the ecu can't compensate or won't compensate when in open loop. So you have been running lean, in open loop the ecu don't read any feedback from the O2 sensor. It just do the calculated mixture from the info it gets from other sensors like intake air temp and coolant temp. It just rely on that nothing has changed from factory and uses the pree set mapping. It calculates how mutch air is pulled in to the engine by calculating pressure and temp to get the likely air density, this is because it doesn't have a air mass meter like cars do.

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XTX 2011. Yamaha Hand Guards, Akrapovic slipon mufflers, Snorkel removed, Airbox drilled, AIS Blocked, PCV, Dynojet Autotune, Kev O2 Controller, Dna Stage 2, KN air filter, mini indicators, steel sprocket cover, cnc levers, cnc mirrors.