I deleted my catalytic converters on my Ford Taurus 2013 N/A because was giving p420 CEL, and tuned with HP Tuners to disable CEL from p420 , p430 and disabled catalyst test and downstream O2 heaters and disabled the FAOSC, I want to ask how downstream O2 sensors (FAOSC) will affect my AFR and fuel milleage is my method best for disabling catalytic converters or I should keep the FAOSC.

I disabled FAOSC because Im thinking downstream o2 sensors will get wrong reading without cats maybe more oxygen or lower.

  • Welcome to Motor Vehicle Maintenance & Repair! I don't really have an answer for you, but this reference (starting pg 60) talks about how FAOSC works when the UEGO develops a bias and can then compensate for it. It might help you to ascertain whether you want to tune that part out or not. – Pᴀᴜʟsᴛᴇʀ2 Dec 28 '18 at 8:46
  • Main purpose of downstream O2s are to monitor cat efficiency, nothing to do with fuel trim. – Moab Dec 29 '18 at 14:33
  • downstreammonitors cat efficency and also there is rear fuel trim and (FAOSC) – Hasan Bağcı Jan 1 at 12:26

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