Unable to advance WOT spark beyond limit

[pghalcrow]

I'm trying to maximize the benefits of E85 by advancing my WOT spark, but no matter what I do, I can't seem to get it to go above 19 degrees advance. I have gone farther than I feel like I should have on the Spark->Advance->Fuel->Flex Fuel table and it appears that the Spark->Advance->Fuel->Alcohol table has no affect. I'm targeting 22-24 degrees advance to see if I get any gain from that, but I can't go past this invisible ceiling.

The log attached shows it going only to 16 degrees when I feel like based on the spark tables it should have been much higher.

[GSXRWS6]

Your alcohol multiplier vs composition table (12636) is still all zeros, it cannot add timing without that table setup. I would back the Flex spark adder table way off before you setup the composition table, and also zero out the alcohol adder table as well. You do not need the flex and alcohol tables both adding timing.

[pghalcrow]

Your alcohol multiplier vs composition table (12636) is still all zeros, it cannot add timing without that table setup. I would back the Flex spark adder table way off before you setup the composition table, and also zero out the alcohol adder table as well. You do not need the flex and alcohol tables both adding timing.

Thanks! I know it would be something dumb that I didn't see. Haven't tried this out yet, but it all makes sense. Does this look right as far as putting [the correct] numbers in boxes?

Screenshot 2024-12-04 135554.png

[GSXRWS6]

That is a good starting point. You can probably be more aggressive at the 50% point once you get it dialed in, I typically have that at about .8 depending on the setup.

[JayRolla]

You can probably be a bit more aggressive. I have my cts-v adding full timing at 50% or above. 40% you're at pretty much max octane and the more ethanol you get more cooling affect. Pretty much at 60% you're getting full benefit of e85. But again, does depend on how aggressive the setup is.