How Does GM Calculates Mass Air Flow?

[bobcratchet555]

I build my base VE tables from filtered MAF data.

Dynamic air calibration from MAF
Dynamic Air Calculated =
(MAF gms/sec X 120) / (#Cylinders X RPM)

VE Calculation from MAF
VE=(DynamicAir X IAT in Kelvin X 0.28705) / (Cylinder Volume X MAP in Bar)

Now put both parts together.
VE=((MAF gms/sec X 120) / (#Cylinders X RPM)X IAT in Kelvin X 0.28705) / (Cylinder Volume X MAP in Bar))

Cylinder volume is 1 cylinder in liters.

i've been wondering for awhile if the MAF can be used as a tuning tool similar to how widebands get used. I kind of assumed that if the MAF calibration is reasonably good maybe it would work to some extent?

[Fast355]

i've been wondering for awhile if the MAF can be used as a tuning tool similar to how widebands get used. I kind of assumed that if the MAF calibration is reasonably good maybe it would work to some extent?

It works and it works very well, IMO. I filter out the transients though. Any TPS change greater than 1% or MAP change greater then 1 KPA results in values not being saved for 500msec after the change. I also make the minimum count; 20 hits so that bogus 1 hit data is eliminated. Once the transient spikes are cleaned up the data is very clean and repeatable. I find the calculated VE table a much better starting point then trying to datalog from a factory VE table. I get the engine running on MAF because it is exponentially easier to get the thing running and datalog the VE data I can. A little hand editing to fill in the blanks and it is up and running well enough to get it to run well for VE tuning.

[bobcratchet555]

It works and it works very well, IMO. I filter out the transients though. Any TPS change greater than 1% or MAP change greater then 1 KPA results in values not being saved for 500msec after the change. I also make the minimum count; 20 hits so that bogus 1 hit data is eliminated. Once the transient spikes are cleaned up the data is very clean and repeatable. I find the calculated VE table a much better starting point then trying to datalog from a factory VE table. I get the engine running on MAF because it is exponentially easier to get the thing running and datalog the VE data I can. A little hand editing to fill in the blanks and it is up and running well enough to get it to run well for VE tuning.

thanks for the tip. greatly appreciated. i'm in the process of building up a 383 LS1 and it'll be the first engine i've done any serious tuning on so, will take all the pointers i can.