VE table estimation

[cesar]

Is there a way to develop a 'rough' VE table through a properly calibrated MAF curve in a GEN III pcm?

i'd imagine i could use fuel mass/air mass and some algebra to find VE..

Has anyone attempted this?

[redhardsupra]

make a custom histogram, with MAP/RPM axis, and then for data use all the other data to calculate the VE.

[cesar]

make a custom histogram, with MAP/RPM axis, and then for data use all the other data to calculate the VE.

lol well thats funny, i have a red hardtop supra myself.


either way.

wouldn't I need to determine MAT? and if so, isnt that based off bias tables?

can't find MAT in the GEN III stuff.

ht.

[Pekka_Perkeles]

I guess the logic is following: compare MAF-based airflow to theoretical cylinder filling.

For MAF isn't it so that you divide MAF grams/second value with rpm (and rpm needs to be divided with 60 to get revs/second). And this again is divided by the number of cylinders. So the end-result is measured airmass per cylinder at certain conditions. Wich then needs to be compared to the theoretical value per each MAP/rpm cell.

In other words, you need to define a custom PID with something like this: ([SENS.40.MET]/([SENS.70]/60))/8

...where SENS.40.MET is MAF value as grams/second and SENS.70 is revs per minute, which is divided by 60 to ger revs per second. And 8 is obviously a number of cylinders.

Am I right or wrong?

Does anyone have Banish' book where the VE formula is presented? I have both books, but cannot find now either of them...

[Pekka_Perkeles]

wouldn't I need to determine MAT? and if so, isnt that based off bias tables?

can't find MAT in the GEN III stuff.

ht.

It's called IAT in GM vocabulary and right now in my Scanner configuration it seems to be [SENS.11].

[jim2092]

VE = MAF / (Displacement x P stp x Speed)

[LSxpwrdZ]

We do not have MAT as a PID in HPTuners for Gen3 stuff. At least I've not seen it as of yet. I do know the other software has this PID to log though. You would need the reported MAT to properly calculate VE. Without that your VE will be scewed using IAT only.

On the Gen3 stuff it's much easier to go the opposite way. Dial in VE first and then generate a MAF table by overlaying dynamic airflow (while running in SD) on the MAF Freq table.

[cesar]

It's called IAT in GM vocabulary and right now in my Scanner configuration it seems to be [SENS.11].

actually theres IAT and MAT in gm vocabulary.


Either way, LSxpwrdZ, i understand the VE would be a bit skewed due to just using IAT, but don't you think it would be better than having to start off at zero? if the IAT gives a sample error of +10% then I would more or less have to decrease the entire ve by 10 percent.

Seems like the GMVE stuff is more appropriate for the e38's huh? since you can log mat and all.

[Pekka_Perkeles]

actually theres IAT and MAT in gm vocabulary.

Ok, sorry. I just haven't ever seen it in a Gen III stuff.

[Pekka_Perkeles]

We do not have MAT as a PID in HPTuners for Gen3 stuff. At least I've not seen it as of yet. I do know the other software has this PID to log though. You would need the reported MAT to properly calculate VE. Without that your VE will be scewed using IAT only.

Which sensor woud it (MAT) use then in Gen III? Or is it somehow estimated/calculated?

I've moved my IAT sensor to intake manifold, so I guess that would then act as a MAT.