B0120 ?

[DrX]

Just want to be sure that I have been understanding this correctly. The description for B0120 reads:

"If engine speed is less than this value, then the PCM uses a dynamically calculated airflow value to determine grams of air per cylinder.
While the airflow is in a "steady state", then a correction factor is updated based on the airflow difference between the MAF sensed airflow and the MAP calculated airflow.
During rapid changes in airflow, the correction factor is applied to the airflow calculations to compensate.
If engine speed is above this value, then the PCM will use the MAF sensor exclusively (if not disabled by DTCs) to calculate grams of air per cylinder.
No updates are made to the airflow correction factor."

So below the B0120 value the engine is running off the VE table (SD mode). The MAF is only used to determine the "correction factor". Correct?

[joecar]

My understanding of it (from reading various forums) is that below B0120 the PCM uses a combination of VE and MAF (leans toward MAF during steady state conditions, leans toward VE during transient conditions).

So it's not really SD mode since the MAF is "blended/combined" in and out at various times/conditions.

$0.02

[dc_justin]

My understanding of it (from reading various forums) is that below B0120 the PCM uses a combination of VE and MAF during steady state conditions, and uses VE during transient conditions.

So it's not really SD mode since the MAF is "blended/combined" in and out at various times/conditions.

$0.02
I'm with Joe on this one.
What I've seen from my observations is that in steady state, the MAF input seeems to be much more heavily weighted than VE. VE comes into play moreso during throttle transitions and such.

[DrX]

Maybe the description for B0120 just needs a little editing to make this clear. The first sentence definitley leads to a different understanding.

[Doc]

I agree with Joe and Justin. I think the key word is dynamic. Now what the ratio actually is or what the formula is btw the blending of the Ve and MAF for below B0120 would be nice to know for CL MAF operation. When going into a transition, WOT rather suddenly, other than trial and error of editing the VE and MAF tables what can we do to approach this more scientifically. More so, what defines the timeline or duration of how long and what percentage the PCM uses of the two players to arrive at the calculated product. Do "We" have access to these values? Or are they predetermined, preset values? Is this the essential reason why so many who have discarded their MAFs and opted for SD's percieved or otherwise evidenced "crispeness" because it is just easier/quicker to do away with the "dynamic blending" of the two tables -MAF operation as opposed to just having to nail down one table -SD, the VE table?