I took a look at my bin in Tunerpro (something I rarely ever do since I use Tunercat)...

I found two things interesting...

1.) It looks like the Slow O2 table in Tunercat is mis-labeled?

In Tunercat, the only Slow O2 table is labeled "Slow O2 Filter Coefficient vs Air Flow". It's values are Airflow vs Coefficient.

However, the table with the same values in TunerPro is labeled "Slow O2 Filter Coefficient Multiplier vs Airlflow". It's values are Airflow vs Multiplier.

2.) There's another table in Tunerpro entitled "Slow O2 Filter Coefficient vs Air Flow".

However, the values are Air Flow vs Time (in seconds).

Is this time value some sort of lag time before the the ECM starts reacting to what the O2 sensor is reporting?

 

The issue you discuss is why it's difficult to describe Calibration items with only titles as opposed to also including the item's address (location) in the Calibration. This is because the item deceptions across the various $8d XDF files are inconsistent, but the hex address locations in the Calibration are the same across the respective BIN revisions.

Can't speak about Tunercat, but the two Tables you reference appear to be:
0x4BD-SLOW o2 INT Delay Time .vs. Air Flow
A time value is extracted from this Table based on air flow. It, and a value from the Table at 0x504=INT Delay Factor .vs. % Adjusted SLOW o2 Voltage Error, possibly coolant temperature adjusted, are multiplied. That product is the ‘Calculated # of Passes through the Fuel Minor Loop required before the INT can be +/-‘d’. The calculated # of passes decreases as air flow and the % Adjusted SLOW o2 Voltage Error increase, providing more frequent INT updates.

It could be argued that this item has nothing to do with SLOW o2, but because the INT can only be updated if certain SLOW o2 error characteristics exist, it's probably OK that 'SLOW o2' remains in the title.


0x4C6-SLOW o2 Lag Filtering Coefficient .vs. Air Flow
A multiplier from this Table, along with the values below, is used to compute the smoothing factor used to Lag Filter L0090=Filtered o2 Voltage for SLOW o2 Error decisions:
- L005D=Coolant Temperature
- Scalar Constant 0x4A0 =60.2% =Coefficient for SLOW o2 Filter Constant used to factor the coolant temperature

BTW, your post has caused me to change the titles of the above items in the document in Post #1 here:
https://www.thirdgen.org/forums/diy-...sor-input.html
That document will answer all your questions about how o2-related Calibration items are used.

HTH

 

I ended up trying something drastic today where I made the coefficient and multiplier values at low air flows the same as the values at high air flows (just to see what would happen). Seems like it got rid of the the lean spot at low throttle... I'll probably start backing the low air flow values back up little by little to see where the "tipping point" is.

 

If in fact you adjusted the 2 tables referenced in Post #2, with everything else unchanged, the 0x3BD table changes effectively increased the INT update frequency at the lower AFs by 200-300% (the approx difference in the times at AF of 56-64 gm/sec .vs. 8-16 gm/sec). BLMs would also be subjected to a more frequent change as well -- both of which would lead to BPW changing more rapidly.

While more subtle, changing the table st 0x4C6 would have the effect of the lag filtered SLOW o2 voltage more closely resembling the o2 voltage just read from the sensor rather than more closely resembling the prior SLOW o2 voltage. This occurs because the lag filtering factor is now 2-3 times larger than before. This could have (note "could") the effect of creating larger and more frequent SLOW o2 voltage errors which could also contribute to more frequent INT updates.

 

Thanks. Yeah it sounds like what I did probably isn't the most elegant way to combat the problem. But at least I proved I can affect it (other things I tried earlier didn't seem to have an effect). I may go back to stock with those tables and maybe try a different approach.

 

I think I figured it out... (the lean spot at part throttle acceleration between 2000 and 3000 rpm)... Had some time to play around with it this afternoon.

I ended up dropping the commanded AFR to 14.5:1, increasing the high-map values for the O2 threshold vs MAP tables to about 850 mV, and scaled down the Inv MAT table by about 10-15% at the mid-high air flow ranges.

Ended up going back to the ANHT MAT Compensation counts table. I had gone to the BDZL (94 LT1 TransAm) table earlier last year (before I got my WB) and at the time it seemed like it helped butt-dyno-wise, but with the WB now, it evidently was more of a detriment. BTW, doing this by itself wasn't enough to rid myself of the lean spot. I had to do the other things above. And doing the above without the ANHT MAT table also wasn't sufficient.

Then a minor correction to the VE tables to account for the change in AFR after all was said and done.

Any rate, seems like it did the trick. The lean spot seems to be gone as I'm watching the WB gauge.. Instead of kicking up to 16:1, the AFR holds at around ~14:1... the transition from part throttle to PE mode also seems a lot more seamless.