Any down side for using MAF from 400 RPM ?

[wesam]

I want to know if there is any down side when using MAF from 400 rpm instead of 4000
I want to change table B8024 to 400 or so in a boosted car with 12 PSI because whan i try to adjust fueling before 4000 rpm it will affect the high rpm region because the area before 4000 rpm is calculated between VVE and MAF
I don't want to modify the VVE table because it seems to be complicated in E38

Thanks in advance

[eficalibrator]

1) Yes, you can force the ECM to operate in "MAF Only" mode by setting this to a low number. GMPP does this on their crate engine controllers, and we do it all the time as part of the normal calibration process before re-enabling "Blended" operation.
2) Tuning the VVE tables in EFILive is a snap. Just work on the appropriate (1,2,or 3 bar) virtual VE table as if it were a normal older VE car and click on the button to recalculate coefficients once you've made your changes. You will have to move the max allowed MAP value above 105kPa, use a proper MAP sensor, and only stick to one of the three VVE tables (usually the 2bar is fine) for this to work.
3) Only tune one airflow model at a time. This means force MAF only and tune the MAF curve, then force SD and tune the VVE table only, and return to blended later. The results form putting in the time here are pretty impressive.

[wesam]

Hello Greg I bought your DVD but i have some question regarding the VVE calibration
should i modify each square in the VVE table separated then generate the coefficients then generate the VVE table or could i adjust more than one square region together ?
Also why after generating the VVE table the adjacent squares will be changed ?

[swingtan]

When adjusting the VVE, use the "Generate Co-Efficients" and "Generate VVE" buttons only once per tune. Because the table is not "real" making changes in small areas can alter the values of cells out side of the area you have changed. Multiple applications of the "generate" buttons will change the VVE shape more than intended and may lead to incorrect fueling.

The VVE is built up in "zones" and any change inside a single zone will be averaged over the rest of the cells in that zone. If you're running a boosted motor and trying to tune the VVE without adjusting the zones, then you are giving yourself a lot of pain. Set your zones up for the expected driving conditions and then start adjusting the VVE. Start off by adjusting as much of the VVE in one go as possible and as it starts to get close to ideal, adjust smaller areas as needed.

Simon