HP Tuner people, whats your favorite way to tune VE table?
09-21-2017, 03:46 PM
#21
Hi subone,
I'll try my best to answer your questions
EFILive has options to let you view the VE table in g*K/kPa, g/cyl, g/sec, or % volume (% being calculated from displacement and IGL);
from what I understand, the VE table's natural units are g*K/kPa (what has been called "GMVE" by Marcin Pohl), and the other units are calculated;
g*K/kPa is "normalized" in the sense it is normalized for pressure and temperature... i.e. if you multiply it by pressure and divide it by temperature it gives you g, the cylinder fill airmass; also note that it is mass, regardless of displacement;
when viewing the VE in g*K/kPa in EFILive, if you change the displacement in the tune there is no effect on the VE table, closing and re-opening the tunetool shows the VE is the same.
Pa = N/(m^2) and N = kg*(m/s^2)
so Pa = kg*(m/s^2)/(m^2) = kg/(m)/(s^2)
( pressure has really strange base units! )
so kPa = Mg/(m)/(s^2)
where M is k*k (i.e. 1,000,000 x)
so g*K/kPa = g*K/(Mg/(m)/(s^2)) = (g/Mg)*K*m*s^2
you can't cancel the g's because then the M would have no units (it would be in the denominator all by itself, but it is not allowed to be by itself) (and also because g/Mg is a conversion, you really can't cancel out the g's);
( lol, you were close, swapped a * for a /... and that nasty unitless M went away )
that is a strange unit, but it is nonetheless g*K/kPa which is more meaningful than (g/Mg)*K*m*s^2 (or K*m*s^2/M if you cancel the g's).
I'll try my best to answer your questions
EFILive has options to let you view the VE table in g*K/kPa, g/cyl, g/sec, or % volume (% being calculated from displacement and IGL);
from what I understand, the VE table's natural units are g*K/kPa (what has been called "GMVE" by Marcin Pohl), and the other units are calculated;
g*K/kPa is "normalized" in the sense it is normalized for pressure and temperature... i.e. if you multiply it by pressure and divide it by temperature it gives you g, the cylinder fill airmass; also note that it is mass, regardless of displacement;
when viewing the VE in g*K/kPa in EFILive, if you change the displacement in the tune there is no effect on the VE table, closing and re-opening the tunetool shows the VE is the same.
Pa = N/(m^2) and N = kg*(m/s^2)
so Pa = kg*(m/s^2)/(m^2) = kg/(m)/(s^2)
( pressure has really strange base units! )
so kPa = Mg/(m)/(s^2)
where M is k*k (i.e. 1,000,000 x)
so g*K/kPa = g*K/(Mg/(m)/(s^2)) = (g/Mg)*K*m*s^2
you can't cancel the g's because then the M would have no units (it would be in the denominator all by itself, but it is not allowed to be by itself) (and also because g/Mg is a conversion, you really can't cancel out the g's);
( lol, you were close, swapped a * for a /... and that nasty unitless M went away )
that is a strange unit, but it is nonetheless g*K/kPa which is more meaningful than (g/Mg)*K*m*s^2 (or K*m*s^2/M if you cancel the g's).
BTW, isn't GMVE only for 07+, or the "e" series controllers, i.e. e60,e67,e38?
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t5munoz (05-01-2022)
09-21-2017, 07:30 PM
#22
TECH Senior Member
( sorry, I spelt your name wrong earlier )
on E38, E67, E92 I see VVE show up with typical values of around 2400 (doesn't show units)...
on 411/GenIII I see VE show up with typical values around 2.4 g*K/kPa...
I haven't verified it yet, but I bet it's a mg/g conversion.
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t5munoz (05-01-2022)
09-22-2017, 08:29 PM
#26
This is actually very straight forward. Datalog an equivalence ratio or lambda error histogram on the same plot as your VE diagram. This is simply the ratio of the commanded equivalence ratio to the actual equivalence ratio. First you must have both of these in your channels list. Commanded comes from the PCM parameters list, and actual is your wideband that you need to have the correct scaling set up for (make sure the scaling the wideband is sending out matches the scaling you have in your VCM scanner).
You want to turn DFCO, STFT, LTFT, COT overtemp, Desoot Mode, and any spark modifiers associated with torque management off (some of these dont apply to older PCM's like the desoot).
Go out part throttle and be as minimal on your throttle transitions as the fuel transient tables are always adding fuel when you tip in. You need to minimize this to get good data. There are going to be outliers in the histogram when you finish each datalogging session so keep that in mind! Select the entire histogram from the scanner (remember the scaling needs to be identical to what it is in HPTuners - you can copy and past the column and row values from HPTuners into VCM scanner to be sure when you are setting up the histogram in the VCM scanner). The first 1 or 2 iterations, I take the copied percentage equivalence ratio error and go in hptuners, select the entire VE table, right click and select paste special - multiple by %. Now you need to look at all the outliers (obviously too high or too low of values in random places), and interpolate individual or small groups of values through them to smooth it by hand. The areas of the map that you didnt hit, hand extrapolate through those areas.
Now go out and repeat. As you get it closer and closer, you can start going up in load and RPM and populating those areas. Also as it gets closer, when you paste the error % into the VE table in HPTuners, use paste special - multiple by half %. It helps approach the correct value without overshooting it I find.
WATCH YOUR Spark Retard table as well when your doing this. You need to make sure your spark retard table has the same exact scaling as your HPtuners High Octane and Low Octane Spark Tables (again you can copy and paste the row and column axis vales). On each iteration, pull timing where you need to and or add timing where you can at the higher loads.
Last note, add a common ground between your HPTuners auxillary input ground, the wideband ground, and a ground near the PCM. This helps eliminate any ground loops that give skewed wideband readings.
Then turn everything back on that you want when your done. BTW you dont NEED to disable the spark modifiers, but I find that keeping the ignition timing as stable as possible when your tuning, yields the best overall tune in the end when you turn it all back on, and can result in a faster process!
That's pretty much it. Hope this helped. Now I need a beer. Good luck!
You want to turn DFCO, STFT, LTFT, COT overtemp, Desoot Mode, and any spark modifiers associated with torque management off (some of these dont apply to older PCM's like the desoot).
Go out part throttle and be as minimal on your throttle transitions as the fuel transient tables are always adding fuel when you tip in. You need to minimize this to get good data. There are going to be outliers in the histogram when you finish each datalogging session so keep that in mind! Select the entire histogram from the scanner (remember the scaling needs to be identical to what it is in HPTuners - you can copy and past the column and row values from HPTuners into VCM scanner to be sure when you are setting up the histogram in the VCM scanner). The first 1 or 2 iterations, I take the copied percentage equivalence ratio error and go in hptuners, select the entire VE table, right click and select paste special - multiple by %. Now you need to look at all the outliers (obviously too high or too low of values in random places), and interpolate individual or small groups of values through them to smooth it by hand. The areas of the map that you didnt hit, hand extrapolate through those areas.
Now go out and repeat. As you get it closer and closer, you can start going up in load and RPM and populating those areas. Also as it gets closer, when you paste the error % into the VE table in HPTuners, use paste special - multiple by half %. It helps approach the correct value without overshooting it I find.
WATCH YOUR Spark Retard table as well when your doing this. You need to make sure your spark retard table has the same exact scaling as your HPtuners High Octane and Low Octane Spark Tables (again you can copy and paste the row and column axis vales). On each iteration, pull timing where you need to and or add timing where you can at the higher loads.
Last note, add a common ground between your HPTuners auxillary input ground, the wideband ground, and a ground near the PCM. This helps eliminate any ground loops that give skewed wideband readings.
Then turn everything back on that you want when your done. BTW you dont NEED to disable the spark modifiers, but I find that keeping the ignition timing as stable as possible when your tuning, yields the best overall tune in the end when you turn it all back on, and can result in a faster process!
That's pretty much it. Hope this helped. Now I need a beer. Good luck!
