Commanded AFR - Tuning Principles - Speed Density - 2 bar
As I am becoming more familiar with the basic "nuts and bolts" of the HPtuner software for Gen III 0411 PCM's I would like to clarify my understanding of the basic principles of setting up the SD only VE table. I have searched quite a bit and cannot really find the answer in one write-up so I will attempt one here. For my benefit and perhaps others.
If the main stoich value is set to 14.63 the Commanded AFR will be 14.63 in all VE table cells that are not affected by Power Enrichment and Boost Enrichment or other modifiers.
I have seen this VE commanded table "model" modified by choosing targets in various places such as idle area AFR, cruise area AFR and wide open throttle AFR and then interpolating the whole commanded target table, so that when you data log and make corrections to actual VE values you will be adjusting to an interpolated table instead of just a table full of stoch 14.63.
Using the flat 14.63 or the interpolated values does not look to me to make any significant difference in the overall tune and final VE values but is maybe more "perfect" using interpolated grid.
It is my understanding that the two variations either of these two commanded AFR "models" only apply to non PE and non BE engine operations, other than modifiers for things like ECT, IAT, etc. There may be other modifiers than just these two.
When throttle position or load is such that Power Enrichment is enabled (AFR values according the to PE table) and/or Boost Enrichment is enabled (AFR values according to the BE table) then the commanded AFR in the VE table will change accordingly in those cells that are affected.
With this understanding it is a simple matter of data logging and making VE table corrections so that the actual wide band AFR equals the commanded AFR.
Do I have this right?
On a separate note, is it even possible or desirable to re-enable any closed loop components after the open loop SD tune is complete?
