MAF-less with 12208322 / 01270001 and 4l80e trans pressures?

Tried to search and read up as much as possible, but wanted to see if there was a definitive answer.
An accurate airflow measurement on this application isn't feasible. But, as I understand it, a COS will allow full use of the spark tables, (not just the first column, which the scan/tune trace showed it was locked into when I test fired the engine). Is this due to the COS performing a calculation to estimate air mass per cyl based on VE and RPM?

Most importantly, will the 01270001/2/3 COS allow me to properly control a 4l80e transmission with no MAF signal? I've read about disallowing certain DTC's to modify the trans pressures, but will the transmission still be calculating load correctly without airflow, as to shift as it was intended? Don't want to fry this guys trans :o

Thanks!

What year/model/vehicle are you driving...?

To get accurate trans line pressure, you FIRST have to get the air/cyl model correct (MAF and VE), then the trans line pressure will be good.

COS ignores the MAF fail DTC's, this allows adaptive spark to function (sliding between HO and LO tables).
OEM and COS both calculate air/cyl in two ways: from VE table, MAP, RPM; and from MAF, and RPM.
Then torque is calculated from air/cyl.
And then trans line pressure calculated from calculated torque (indirectly via "torque signal" pressure, see hydraulic schematics).
And, spark advance is looked up and/or calculated based on on air/cyl, and this in turn influences the torque calculation.

4L80E can be controlled by the Gen III PCM, but you need a segment swap of the Trans and Trans Diag segments (from the same OS id), and you need minor rewiring (2 pins)... to obtain the correct segments, you may need to swap the OS first.

To make sure the trans is ok, you MUST connect line pressure gauge and observe it during tuning (which should be done on dyno)... also monitor trans fluid temp, if it starts getting high very quickly, slipping is occurring (air/cyl model is wrong).

Its a swap application, 68 Impala show car with w30 olds style functional ram-air hood.
The genIII engine and 4l80e combo is up and running with a preconfigured pcm and harness (looks like they used an 01 2500 silverado LQ4/4l80e calibration).
The trans may be a little more tricky, so only looking at spark as a first step: Sounds like the COS isn’t the answer to my spark table issue; i dont mind only running off of the low table as i can tune it to what the engine wants safely, but with no MAF plugged in, it just reports a constant 2.03g/s value which makes the air/cyl value hang only in the first column of the spark table. How are people getting around that in a maf-less scenario? I still cant believe i couldnt dig up any mention of this issue. I have to be missing something silly...

When i get to the shop tomorrow morning i’ll double check the maf dtc’s are still set and try to determine if the actual ignition timing is really stuck in the 0.04 air/cyl far left column or if its just the trace marker in the tune display.

Thanks for the clarification joecar.
So, I did verify that I do not have a spark issue; the correct timing values are being pulled from the entire spark Low table, the trace simply wasn't following the correct pid. I might have done something funky in the sequence of opening the tune and scan tools and connecting or something. The trace feature didn't want to start at first today, but have it working fine now.

Back to the trans pressures; Can definitely monitor those items while proceeding.
My very first order of business was going to be VE table calibration with serial wideband, so its contribution to the torque model will be accurate.
While tuning the ignition timing on modified engines I usually try to get some data points for mean best torque to do a sanity check on the shape of the "optimal timing" table which should refine the torque model further.
So, if I have the b0120 airflow calc threshold set high, and MAF tests set to fail and dtc's set, as long as the PCM will ONLY use VE/MAP/RPM to calculate air/cyl and no "weight" is given to the invalid MAF signal, sounds like the trans pressure calcs will be fed accurate information. Sound solid?

Make sure the MAF DTC triggers immediately.

MAF should fail regardless of B0120.

Also log GM.TRQENG, and GM.TFMPRS.

Post your log file here.

What was causing logging to not start?

Finally had a chance to do some testing and all seems great on the calc airflow and trans pressures. :)
I think the trace not starting was just due to either me having two instances of the tune tool open, or modifying the tune file while the scan tool was logging. It's worked without issue recently.
Running into some gremlins with the aftermarket throttle body on this same project, but will start a new thread on that one

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