AutoVE and AutoMAF Tunes

[hapnermw]

As someone new to EFILIVE and tuning I found this thread that explains the rationale for the AutoVE tune setup very helpful. It would be useful to add it to the sticky.

http://forum.efilive.com/showthread.php?t=7744&highlight=Questions+professionals

It makes sense to isolate VE to tune it.

For those retaining their MAF, it would seem to also make sense to have an AutoMAF tune that isolates the MAF and allows it to be tuned without VE interference. It appears that restoring the MAF tables and setting MAF cut-on RPM to idle on the an AutoVE tune would switch AFR from being 100% VE commanded to 100% MAF commanded. Is this correct?

With both VE and MAF calibrated independently, it would seem that the PCM would be in the optimal state to blend them using whatever secret formula it uses.

[zrx1200]

have a look at the auto vve tutorial well worth the read.thanks swintan/others

[hapnermw]

I have looked at the tutorial. It's nicely done but it doesn't cover MAF tuning.

I've reviewed the various MAF tuning discussions both on this forum and elsewhere. The generally accepted approach is that after completing AutoVE the MAF frequency is reset to normal and the AutoVE procedure is used to tune the MAF air flow tables.

I'm tuning an LS7 and there doesn't appear to be a way to force it to use MAF airflow and ignore the VVE. So, it's not clear what exactly is being tuned once the MAF has been enabled. The assumption is that since the only change was re-enabling MAF that any commanded AFR delta is due to MAF miscalibration. However, since the commanded AFR is likely some function of VVE and MAF simply applying BEN to the MAF table likely doesn't result in a true MAF calibration.

So, has anyone come up with a way to accurately calibrate the MAF tables in isolation using BEN?

[Aint Skeered]

DO you have a (B0120) RPM Threshold for Airflow Calculation ? If so set that to 200 rpm's instead of 4000 and that will put you in Maf only mode from 200 rpm's up.

I have not looked at the ls7 stuff so I dont know what that OS looks like.

[WeathermanShawn]

I had similar experiences when I first stated the AutoVE & MAF tuning procedures. I think the procedure is superior when you choose to retain a OLSD or OLMAF tune. That is not to say that nailing down your VE/MAF calibrations are not important.

A lot depends on your tuning goals. When doing AutoVE, I was rich almost everywhere. During AutoMAF, I was rich everywhere. My tuning goals were to remain closed loop using a 'calibrated' VE & MAF. As soon as I went back to closed loop..lean everywhere.

So in my experience, having VE and MAF calibrated separately, did not equate to an accurate AFR while in closed loop. The two parts did not equal the whole. I tried various lower MAF thresholds, but found my AFR's were all over the place. Isolating the VE/MAF, and then each added together did not produce the results I desired.

I found more success tuning for Closed-Loop for street and everyday applications.

[joecar]

Yes, there is always various unknowns... sometimes you see a factory IFR table and wonder "why did they (GM) do that...?"

[hapnermw]

The E38 ECM doesn't have B0120 and I don't see any other MAF calibration that would control when MAF overrides VE. It appears that the only option is to AutoVE and then tune MAF to compensate for whatever changes enabling it results in.

WeathermanShawn, thanks for the info on your experience. I hadn't thought about tuning IFR so at least its another option if VE/MAP tuning isn't adequate.