MAF error not matching WBO2 reading

[FetzerValve]

Hey guys,

I'm trying to clean up the email tune that I'm currently running and I'm a bit confused. I did a quick log while running some errands around town to try to clean up the tune in the areas that I'm not in boost. I'm logging my AEM wideband through the EGR channel with some custom math. My WB02 reading is staying pretty solid around 1 (lambda reading) but my MAF error histogram is showing readings as rich as -14. Can anybody take a look my log and tune to see if I'm doing something wrong? I'd really like to start making some changes to this tune but I don't want to grenade the engine as the truck is my daily driver.

2010 Silverado 6.2
BW S475
850CC injectors
LS9 MAP
E85 tune

[07GTS]

prob the virtual flex sensor, it is best to get the actual sensor and wire it in properly, the virtual flex can be out as its just based on the trim errors, or if u are running e85 constantly 85% just set it up to suit that stoich and disable the virtual flex

[FetzerValve]

prob the virtual flex sensor, it is best to get the actual sensor and wire it in properly, the virtual flex can be out as its just based on the trim errors, or if u are running e85 constantly 85% just set it up to suit that stoich and disable the virtual flex

Thanks for the insight. I run the truck on only corn fuel. I don't test the fuel like a lot of people seem to do. Can I just set up the stoich values for something like E75 so that I have a built in buffer for when the E85 isn't testing at 85%? Going into winter, I've heard that a lot of stations in my area test at around E70ish.

Is an ethanol sensor considered mandatory for running E85? I understand that it helps determine what stoich should be but if I'm not looking for max power and timing, it seems logical that I could just turn off the virtual sensor and set up my stoich value for something like 10.4, which is the value in the 75% ethanol cell.

[blindsquirrel]

Sensor not required if you are using race E85 out of a drum from a reputable supplier. Otherwise you are just guessing and crossing your fingers.

Would having the tune fixed at 70% E be safe if the fuel station gets a batch of "E85" that's only 55%? That would still qualify as "E85" and be legal for them to sell it labeled as such.

In the United States, the exact ratio of fuel ethanol to hydrocarbon may vary according to ASTM 5798 that specifies the allowable ethanol content in E85 as ranging from 51% to 83%.

[FetzerValve]

Sensor not required if you are using race E85 out of a drum from a reputable supplier. Otherwise you are just guessing and crossing your fingers.

Would having the tune fixed at 70% E be safe if the fuel station gets a batch of "E85" that's only 55%? That would still qualify as "E85" and be legal for them to sell it labeled as such.

I appreciate your input. If I stay on the conservative side of timing, I should be safe just setting stoich for something like E70 even if I end up with a tank of E55, correct? I'm not worried about making max power. I just want a nice, reliable daily driver. The fuel stations I typically use haven't tested any less than E70 in the past. There are a ton of highly modified vehicles in my area using these very same fuel stations for their E.

[07GTS]

its not really the timing or max power its the change in ethanol % is a shift in AFR, if u have a WB in the vehicle at all times and u can tweak it every time it changes per fill up then thats one way or just fit the flex sensor and never have to worry about any change in ethanol mix

[FetzerValve]

its not really the timing or max power its the change in ethanol % is a shift in AFR, if u have a WB in the vehicle at all times and u can tweak it every time it changes per fill up then thats one way or just fit the flex sensor and never have to worry about any change in ethanol mix

I do have a wideband but I'd rather not have to tweak the tune every time I fill up so it sounds like I'll be needing a sensor. Thanks for the help!