I have already unplugged the stock 02's using the TFI. If you tune on the colder 'front' cylinder, and dial it in, it only makes sense that the 'hotter' rear cylinder could use some more fuel to cool it.
BTW, I would be tuning with Lambda, not A/F Ratio....
Tis true that an ability to alter the ratio of the rear "only" would cool it down somewhat. It presents an interesting digression as to how much one could cool it down with fuel alone without running too rich (building up carbon) to alleviate the lessen air cooling ability of it's location.
However more pertinant is the fact that you are using the TFI which unless I'm missing something it does not have the ability to (at least as far as user input goes) tune one cyclinder different than the other.
A SERT, SEST or TTS does in fact have this ability but last time I checked they were not dedicated closed loop. Albeit one could concievably attempt to adjust the open loop maps based on input from a closed loop meter so as to attempt to map lookup tables to give you desired deviation from stoich from data inputted from the MAP, ION and TPS in real time.
But it appears you are using the reports from the LM1 Wideband to manually tune your TFI after reading the meter on LM1 during operation. I kinda tend to think it would be better to use the front cylinder in this scenario since tuning it to the rear could cause to lean a mix in the front (since the TFI cannot separate the two settings).
Further the ECM ( I assume you're still running an OEM ECM) is set to give the rear a tad more richness to alliveate the lack of cooling induced heat. So if you tune off the front I would "think" the ECM compensation would still effect correct results, but tuning off the rear might cause an undesirable scenario in the front.
Anyhow that's my take on it, good luck with it. You know what would be cool is to hook it up on the front, read the ride and then switch to the rear and read the ride both before and after you change the TFI settings. Understandably that would be a bit of work but none-the-less interesting to record the data for decipher.
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(To me) the Air - Fuel ratio is just another relationship to the end scenario, which is stoich or the deviation from it for desired results.
Lambda does offer a compartmentalized view of this path, but it's all still about the same bottom line.
AFR = xA/xF
Lambda = AFR/AFR at Stoich
Stoich is the scenario at which "all" the fuel is burned up in the combustion process. These is rarely possible and even when it reaches close parameters it can cause the engine to run hot.
"How hot" it can take is what the EPA shoots for to save our precious environment that has somehow survired all the volcanoes, and organic waste gases since the dawn of time.