E38 2 bar speed density OS cylinder airmass plummets

[Grant]

The car starts and stays running with the factory OS. When I applied HPT's 2 bar speed density OS I re-populated the high frequency MAF table, re-scaled the MAP sensor back to stock, and populated all the VE tables (interpolated over from a known good C5 PCM with a very similar motor).

Unfortunately shortly after startup cylinder airmass plummets. Injector pulsewidth goes with it, and the car stalls. MAF, VE and dynamic airflow do not plummet.

It's flex fuel on DW injectors. Stoic ratios were doubled and IVTs halved in order to get the injector flow values to fit.

I've tried failing the MAF and running pure speed density, and it still dies.

The car is a 2007 C6 Z06. Thanks for any help.

clubsport_no-airmass_stall.hpl
clubsport_mast_initial_2barve.hpt

[5FDP]

Here is a problem you are forgetting about. The C5 computer is a GEN 3 computer and we are working with a GEN 4 computer that no longer used the regular primary VE table. They used VVE instead. If you look at a stock VVE table in the EDIT tab all the values are well into the thousands. Like 1,000-3,500.

So because of that you must keep the same values over into the 3 new VE tables on this E38. This is why when people swap to this OS upgrade, they take the stock VVE and paste it into an excel speadsheet, swap the axis around and paste it back into the IMRC open/closed/DoD VE tables.

You will never get it to run if the VE tables have values between 30-105 like it is now.

[Grant]

Thanks, I'm sure that's the problem. Any idea what number signifies 100% VE in the Gen 4 tables? I'd erroneously assumed 100 = 100%.

[blindsquirrel]

If you set the Units on the VE table to show 'Percent (%)', you get numbers like 2000. Set units to 'Number ()' the same cell is 20. If you set it to Percent and put in 20 you've got 100x less fuel.

Maybe the labels are backwards after all these years, but it doesn't matter. Bigger numbers = more fuel, use whichever Units you want.

[Grant]

If you set the Units on the VE table to show 'Percent (%)', you get numbers like 2000. Set units to 'Number ()' the same cell is 20. If you set it to Percent and put in 20 you've got 100x less fuel.

Maybe the labels are backwards after all these years, but it doesn't matter. Bigger numbers = more fuel, use whichever Units you want.

Neither my VE tables nor the original VVE tables have an option to change the units when I right-click on them. It's greyed out.

I searched and found HPTuners employees saying the table's units are g * K / kPa. So the PCM seems to use the ideal gas law, where mass is proportional to pressure and inversely proportional to temperature. So I figured we need to solve for cylinder airmass * MAT / MAP:

PV = nRT
MAP * VE * cyl-vol = (m/M) * R * MAT (where m = cylinder airmass and M = molecular weight of the gas; n = m/M)
VE * cyl-vol = (m/M) * R * MAT / MAP
M * VE * cyl-vol = m * R * MAT / MAP
M * VE * cyl-vol / R = m * MAT / MAP

To express a VE % as a value in a Gen 4 (V)VE table, it should be:
0.028.97 * VE * cyl-vol / 8.314, or
0.003484 * VE * cyl-vol

Using ccs for cyl-vol increases the result by 1,000,000 over using the base SI unit of volume, m^3. However the answer is expressed in kg * K / Pa, 1,000,000 times less than g * K / kPa. So these two unit conversions cancel out.

...but this doesn't fit the table values the PCM is looking for. I get numbers 1,000 times smaller than they should be. I'm not sure if I'm doing something wrong, or if the table's units are really in mg or something.

The other weird thing is stock VVE values keep going up at higher RPM. My guess is this is to make sure the car runs rich if the MAF fails and it starts actually using speed density at higher RPMs.