"Burble tune" issues: Commanded spark retard and extra fueling not occurring in decel

[turabo87]

Wanted to see if any tuning gurus can chime in and give me some ideas on what might be going on with this tune. Was tuning a bolt-on's C5 FRC on a MAF tune, but he had a special request to give it more "burble" during decel, aka the "burble tune". I'm familiar with the combustion dynamics to make this work:

1. Extra fueling during decel (or at least some fueling during decel)
2. Significant timing retard from what's considered optimal during decel.

For point#1, I wanted to achieve this with the Dynamic (VE) map in areas of vacuum (15-20kpa rows), by putting about 50% extra fuel. However, because it's a MAF tune, seems like it's not fueling due to the dynamic disable above that the disable RPM. Wanted to know if there might be a fueling workaround for the VE table if on a MAF tune. PS, I had DFCO off when doing the testing.

For point#2, and this is the one I find really odd, I modified from the spark advance tables (HO and LO) the first two spark rows (which from the data logs is where decel occurs) from 30-34 degrees advance I brought it down to 5-10 degrees. Despite commanding this, the data logs still showed 30+ degrees advance during high rpm decel. During decel, it wasn't until maybe RPMs reached around 2000-2500 or so that finally I could see timing retard to 10deg which at that point you could here the burble. I'm wondering what other behind the scenes tables might be preventing the commanded spark of 5-10 from occurring. I don't think it's data interpolation on the spark tables either because I made sure that first two rows were changed to equal values.

Appreciate the help.

[3 GENS]

I on the other hand wanted to get rid of those loud crackles on my 2011 camaro ss if i were you get a look at a stock tune file from 5th gen camaro ss and look at the minimum spark , the adaptive idle spark control coast both over and underspeed, idle spark advance coastdown, and under fuel DFCO entry spark and exit spark, and last the CFCO spark, to refreance how far they pull the spark. as for the fuel getting rich it might be in the blend time for the DFCO. I played with these tables and did not touch the main timing tables at all. hope this helps.

[turabo87]

I on the other hand wanted to get rid of those loud crackles on my 2011 camaro ss if i were you get a look at a stock tune file from 5th gen camaro ss and look at the minimum spark , the adaptive idle spark control coast both over and underspeed, idle spark advance coastdown, and under fuel DFCO entry spark and exit spark, and last the CFCO spark, to refreance how far they pull the spark. as for the fuel getting rich it might be in the blend time for the DFCO. I played with these tables and did not touch the main timing tables at all. hope this helps.

Well I figured out the spark retard. This might help whoever wants to do the ?burble tune? on a C5 Corvette. Because throttle is closed during decel, the spark table that applies during decel is the idle drive spark advance. Values here also needed to be change to 5 deg for top spark row. Wasn?t necessary to do both rows, only first spark row up to 1600 RPM. Worked perfectly.