4MPG on swapped LS3?

[fls350z]

Yep we see that alot on stick engines, for one reason or a other the alcohol content gets too high and it gets real rich. Think accepted content is less than 7* ? Can't remember been a while since I've dealt with this issue tho

I'm not following. Alcohol? Are you saying the ECM changes from standard gasoline settings to some alcohol settings?

[blindsquirrel]

Flex fuel is disabled in the one tune file I looked at, so that's not going to cause it in this case.

On the virtual flex fuel, it infers the alcohol content based on fuel trims... so anything that causes the trims to be off eventually skews the alcohol percent and it just spirals out of control until it's running so rich or so lean it'll misfire and/or even cause a no-start. Virtual flex is dumb and stupid.

[fls350z]

Flex fuel is disabled in the one tune file I looked at, so that's not going to cause it in this case.

On the virtual flex fuel, it infers the alcohol content based on fuel trims... so anything that causes the trims to be off eventually skews the alcohol percent and it just spirals out of control until it's running so rich or so lean it'll misfire and/or even cause a no-start. Virtual flex is dumb and stupid.

Ahh I gotcha. Sounds like another "good idea, terrible execution" thing.

[fls350z]

Update. Double checked vacuum from PCV and cold air intake, cleaned it up and my LTFT started coming down a good amount. Is this significant?
Couldn't upload the 10MB log so I created a Drive link. https://drive.google.com/drive/folde...vi?usp=sharing

The 1.3 tune is the same as before, the log is what's important. Also, when the LT B1/B2 gauges turn red in HPT, what does it mean?

Edit: I have not reset the ECM or LTFT. Would it be worthwhile?

Edit2: UPDATE: I haven't gotten around to fixing it but my current guess is due to considerable CAM overlap without proper tune, computer reads lean due to fresh air being pulled into the exhaust stream, so the computer dumps fuel into mixture to compensate. Going to have to research how to properly tune for this.