Experience with GM Performance Parts controller?

[Dynotuner]

Has anyone spent significant time with any of the GMPP PCMs? I ran across one a couple of weeks ago and had trouble disbling the MAF to work out the VVE table. The part number of the one I was working with was 19201790 (basically an E67 PCM with OS 19211212) running an LS3. When I disabled the MAF (using Swingtan's E38 guide), the AFR went incredibly rich and the MAF reported a constant 1.9 grams/sec. I made some large adjustments to the VVE table and of course got the AFR closer the the commanded (E67_AFRATIO_DMA). As a test to see how the system would react with the MAF enabled, I did that before going too far with VVE tuning and found the AFR measured much leaner (almost too much) everywhere I made adjustments while it was still too rich disabled - even light throttle cruise where I wouldn't expect the MAF to have as much interaction.
Any input appreciated.
Files attached = runs6.7 are before MAF disable and runs8.9 are after

[gmh308]

Has anyone spent significant time with any of the GMPP PCMs? I ran across one a couple of weeks ago and had trouble disbling the MAF to work out the VVE table. The part number of the one I was working with was 19201790 (basically an E67 PCM with OS 19211212) running an LS3. When I disabled the MAF (using Swingtan's E38 guide), the AFR went incredibly rich and the MAF reported a constant 1.9 grams/sec. I made some large adjustments to the VVE table and of course got the AFR closer the the commanded (E67_AFRATIO_DMA). As a test to see how the system would react with the MAF enabled, I did that before going too far with VVE tuning and found the AFR measured much leaner (almost too much) everywhere I made adjustments while it was still too rich disabled - even light throttle cruise where I wouldn't expect the MAF to have as much interaction.
Any input appreciated.
Files attached = runs6.7 are before MAF disable and runs8.9 are after

Main difference in the GMPP tune from factory tunes is the MAF start point...from memory it runs from 800rpm. I dont have a file handy to check.

Which MAF are you using? GMPP supplied blade MAF?

[Dynotuner]

That is another issue - in this OS, I don't see the RPM point for MAF 'start'. "Steady State" RPM threshold = 2500. MAF is sotck with LS3 crate engine.

[gmh308]

That is another issue - in this OS, I don't see the RPM point for MAF 'start'. "Steady State" RPM threshold = 2500. MAF is sotck with LS3 crate engine.

mmmm...MAF hi/lo enter/exit points seem to be missing. In GMPP tunes they are 200/100 vs normal 4000/3900...i.e. MAF normally dictates 100% of airflow needs at 4000 rpm onwards, whereas GMPP is MAF from 200rpm...so if you have a MAF plugged in and it is not failed, then the VVE would normally be ignored...except for its influence as the speed density "MAF" reference calculation which among other things helps smooth out fueling during airflow transients.

[Dynotuner]

I've seen the 200/100 RPM before in other performance PCMs. I must not have properly failed the MAF on this application.

[ringram]

Saw the same issue a while ago. Something was definitely weird on the GMPP E67.
I recommended the guy run a full auto-ve and confirm with MAF off, (or even removed) then re-add maf later.
Im not sure what he did. But it wasnt running right in any case. I think he had an issue with the customer and wanted to play about with it himself.

[Dynotuner]

I'll try again with MAF off and fail parameters double checked to see what things look like. I suppose I could always reflash with a stock OS and start over, but that sounds more time consuming overall. The bottom line is that the engines run well as is and can be dialed in with minor changes, but I'd rather not be MAF dependent from cranking speed.