Flex Fuel and negative timing areas

I have a new to me 2010 CTS V A6. It came with some bolt-ons, pulley, about 1000cc injectors and tune. I had to tweak the maf a little, but now its within 3% or less. Throwing a flex fuel sensor on it to run some ethanol. Doing some research about Flex Fuel tuning and see that most stock FF vehicles tables actually show areas that have negative timing, which kinda throws me off. Turns out Ethanol likes less timing in some places. Can I not just use the Flex Fuel adder table to add timing?

I just wanted to check with the pro's before fillng the tank. Here's my check list. Copied some settings from my Camaro's Flex tune, should I ditch steps 2-5?

1. Sensor is enabled, set to sensor
2. Max E set to 85%
3. Comp Change Threshold 1.0
4. Delay Volume 0.01
5. Transitional Volume 0.01
6. Multi vs comp 0 0.20 0.65 0.85 100
7. Populate Flex Fuel adder table starting at .5 degree all the way up to 4 degrees (to start)

I have no KR now, so my plan was to start with this and see where it takes me. My spark adder tables usually net me around 18 degrees on 93, seeing about 12.5 boost. If the E% is good, all in I should only see 22 degrees of timing at WOT. Does this sound reasonable?

Less timing is needed in lower cylinder airmass regions and then can be ramped in…

Attachment 120301 Is this a good starting point?

I would grab a caprice ppv file and use the flex spark from that as your starting point.

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Originally Posted by justhereforinfo

Attachment 120301 Is this a good starting point?

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No it’s all positive lol

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Originally Posted by justhereforinfo

Attachment 120301 Is this a good starting point?

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What exactly is this table doing? adding and removing timing from the base table for flex fuel? I assume there is a multiplier based on alcohol content percentage somewhere else?

My gen3 is supposed to do flex fuel but I dont have a table like that, I never see it before, so I wish to learn more about gen4

its an adder to the base spark table (high octane)

The blend factor is the multiplier

Caprice ppv file will get you heading in the right direction on the flex set up.

Personally, I would use the Caprice PPV flex table but set the WOT high load rows to 0 to start with. Blend them back into the rest of the table so you don't get timing bumps. Then tune from there once fuel and everything else is good.

Thanks all. I got the caprice file from a member on the V forums. Im gonna start with a max of +3 because I like to live dangerously.

CORRECTION: I was given a CTS V specific Flex Fuel table that someone took the time to create. I think this will probably be a better starting point than the caprice. But again, I'll start off small and log while reading butt dyno.