Unusual KAMRF2 Values - Lean/Stalling on Sharp Decel - Mono vs. Stereo HEGO(s)

[entity-unknown]

Summary of this story: I found the NUMEGO function "Number of HEGOs - NUMEGO (Output Ports)" and the relative table "Injector Output Port (NUMEGO) - FN1327" and set it all to 1 since I have a single/mono O2 setup. Now KAMRF1 & KAMRF2 along with all the calculations that are relative to them are based off a single HEGO's stats i.e. true 1:1, so calcs are consistent for the ECU, Tuner Pro and myself. I've had this fix in for about a week and all my tunings efforts have massively improved plus I can finally hit the upper half of the MAF curve.

I only have one HEGO vs. two or Mono vs. Stereo as Decipha referenced in his awesome "Parameter Comments" (1 channel vs. 2 channels). I've seen plenty of times where my values for KAMRF2 would be extremely off despite no sensor connected. I'm not sure if the wiring is even there since this is a break out harness for the injectors, and I think the ignition/emissions/O2 sensor for an 87-91 Ford Truck MAF swap done in the 90s before I bought it. The MAF/302 HO donor was an 89 Mustang. Ford Speed Density trucks like mine I believe all came with a single O2 sensor which is why I gather the truck MAF conversion harness only has 1 O2 port.

When the KAMRF2 goes out of wack, it goes super lean or what I think is perceived as a voltage drop to 0.000v? The value seems to always be 1.156 or 1.157. I don't see any blatant voltage drops elsewhere in the dashboards either. Also HEGO2 & Lambse 2 report normal when this happens so it's not a phantom HEGO2 source. Screen shot attached.

It seems to mostly maybe always happen when I'm cruisin or hittin the throttle to say 40-50+ then go to slow down sharply. These are all tuning runs too so a bit more aggressive than normal driving but it's happened with all my tests/MAF curves good and bad for over a year now. The calcs from the failed KAMRF2 value is part of the calcs and it starts to run bad and will stall if I don't recover it with throttle when this occurs. If I bump the throttle a bit and hold it or cuz I have no choice but to stop, shift to Neutral and rev up just a bit to say 1100+ RPMs, everything is fine, KAMRFs is all normal again, 1:1ish w/ KAMRF1 but if I don't rev it, it will stall. Once I recover it for a few seconds, I can sometimes let it idle and it'll be fine but not always. I can start up again too if it stalls, but clearly not ideal.

KAMRF2, HEGO2, Err2%, etc. often differ from the KAMRF1/HEGO1/ERR1 etc. It was explained that it's probably just #2 readings from say half way between the time when #1 was recorded and that made logical sense at the time but the behavior/evidence suggests something different because the failed value sticks until I "recover" it with the throttle as said.

If the ECM was going bad in some way specific to the KAMRF2 RAM since KAMRF1 always behaves as expected, I'd figure the KAMRF2 would have more erratic behavior vs. just specifically, only when I let off the throttle when cruising or hauling ass but casually letting off is not an issue either so this seems more computationally related than hardware. It's also rare it does this but I almost always ease off the pedal by habit as is.

Regardless, I found the settings to define a single/mono O2 sensor in Decipha's A9L2 code under the NUMEGO functions as said in the Summary. Since only 1 O2 sensor is defined and my values are consistent, there is no need to chase down the mystery of where the weird signal is coming from unless the same weird shyte happens but thus far this is the only anomaly I've ever seen :)

[decipha]

if hego 2 is removed it must be disabled in the tune otherwise the ecu will try to use it til it failsafes