Measured AFR Correction and Rear O2 Sensor Consideration

Hello,

I have a 2010 USDM Subaru STI, with Cobb 1050x injectors (which I believe are made by Injector Dynamics) and a Perrin cold air induction. I have asked for and received the scaling information for both from the manufacturers and input these values into the appropriate tables.

I've gone through the MAF Rescaling & Injector Scaling courses and it pretty much makes sense but have a few questions. During the closed loop logging, I'm still generally getting a minus 12 to minus 25 trim (on sum of "A/F Correction #1" & "A/F Learning #1") mostly on idle and a much smaller difference at cruise. This seems to be an injector latency issue, and I've gone through 3-4 iterations of reducing the latency values by 10% each time and relogging) but that took me from minus 25 to around minus 12. It seems like a pretty excessive reduction from the manufacturer's values and I'm still nowhere near zero so it's a bit strange.

I saw in one of the courses that if the rear O2 sensor is still installed (which mine is) that the "A/F Correction #3" value also needs to be considered but I'm not clear on how. Does that mean in addition to looking at the sum of ("A/F Correction #1" & "A/F Learning #1") also look at the corresponding sum of ("A/F Correction #3" & "A/F Learning #3")? And both have to be under 5%? Or does that "A/F correction #3" value change the way I need to interpret the difference between the #1 values?

I'm also thinking of just removing the rear O2 sensor so I don't need to deal with this, would that pretty much solve the dilemma here? And to remove it, is it just physically removing (or disconnecting) it and disabling the CEL codes or would I need to update something else somewhere?

Appreciate any input on this!

I'm wondering if I may have written this overly confusingly so will try to simplify what I'm trying to figure out. To get the injector scaling dialed in (assuming MAF scaling is correct). My understanding is that the sum of long term trim and short term trim need to be close to 0 or less than 5%:

* "A/F Correction #1" + "A/F Learning #1 = should be < 5%

If the sum is above this threshold, need to adjust the injector scaling (either flow and or latency) according to the following rules (assuming normal running conditions):

1. If the error is only at idle but within an acceptable range at cruise (3.2k rpm), then it's most likely a latency issue.

2. If the error is both at idle and at cruise than it's a flow (and possible also a latency) issue.

Given this, how do I figure in the rear O2 sensor #3 variables, is it one of the following:

--------------------------

1. "A/F Correction #3" + "A/F Learning #3" = should also be < 5% in addition to the corresponding #1 values and both have to be under 5%?

Or

2. "A/F Correction #1" + "A/F Correction #3" + "A/F Learning #1" = should be < 5% or something of that sort?