got a link to explain this? I have NO issues with my tune except for the random 16.4 , and you claim its from my tune not a cat test
There is plenty on open loop on the other forum, I would browse there a bit if you are interested. Overall the Narrowband does not tell the PCM if things are rich or lean in plain english... the PCM needs to know how to read the exhaust pulses coming through the exhaust. An aftermarket cam changes the size and timing of the pulses of unburnt air coming through and creates a "lean condition" according to the PCM's interpretation of the O2 sensor. It will then add fuel in terms of LTFT and eventually it will come back around to a normal reading after it has drowned the motor in fuel with large positive LTFTs. If you have done maf tunes that add fuel in these areas, you will find that you are probably running quite rich via a "stupid" o2 sensor that is a wideband... widebands are slow enough to read average air fuel and ignore the pockets of unburnt "overlap" air coming through the exhaust. They are also typically much further back from the motor to get a better mix of air.