Does the spark table always use GM.DYNCYLAIR_DMA for the Grams/Cylinder reference?

[BlackGMC]

I was just wondering if the computer always uses the GM.DYNCYLAIR_DMA for the Grams/cylinder reference whether your in SD or MAF???

thanks

[SSpdDmon]

There should be a cylair_dma for MAF calculation.

[voda1]

From the cal_link.txt file in C:\Program Files\EFILive\V7.5\Configuration:

;High octane spark map
B5913.ROW=SAE.RPM
B5913.COL=CALC.CYLAIR,GM.DYNCYLAIR,GM.DYNCYLAIR_DM A,GM.CYLAIR_DMA

shows other choices.

[SSpdDmon]

Yeah - you want the DMA (direct memory access) PIDs. The last 2 should be clearly labeled for speed density and normal.

[joecar]

Any one of those can be used to view which cell in the spark table is being used, but... the DMA pids are what the PCM is going to use to do the lookup (DMA meaning that the pid's value is read frpm the PCM's memory, right in the midst of when it is calculating and looking up).

My understanding is the PCM may use DYNCYLAIR_DMA when running from VE and CYLAIR_DMA when running from MAF (i.e. dynamically).

Of course, when VE and MAF agree with each other and the air temperature model is correct, DYNCYLAIR_DMA and CYLAIR_DMA will be the same.

A few experiments could be done that would indicate which is being used and when:
- zero the VE while running MAF, log SPARKADV and the DMA pids,
- zero the MAF while running VE, log SPARKADV and the DMA pids.


Summary-Notes -> see post #2


See my typo correction.

[SSpdDmon]

If you zero out the VE in SD, you probably won't get enough fuel for the engine to sustain idle....or am I missing something?

[joecar]

If you zero out the VE in SD, you probably won't get enough fuel for the engine to sustain idle....or am I missing something?

Ah, I misstyped, see my correction above.

[SSpdDmon]

LoL