Virtual Flex Fuel Disable questions

[WS6HUMMER]

Can I just hit disable? The reason I ask is, I've got a Silverado that has an evap leak at the canister, I assume this is what's throwing off the VFF calculations causing the truck to think it has 44% ethanol in the fuel content raising stoich to 12.18 in CL. I'm just wanting some input from some of you who may have ran across this type situation before & if what I'm wanting to do will even work. Also do we have the ability with the scanner to do a fuel density reset?

[5FDP]

Just disable it and set the whole stoich table to 14.68. That feature is pretty much useless because there is no real sensor.

[WS6HUMMER]

Just disable it and set the whole stoich table to 14.68. That feature is pretty much useless because there is no real sensor.

If I didn't get an answer that's what I was gonna try, along with zeroing out the Alcohol adder & multiplier tables, just didn't know if it worked that way.

[HeavyChevy305]

Disable the sensor and on the Stoich AFR table set cell 0.00 to 14.32227. You don't have to zero out the alcohol tables.

[WS6HUMMER]

Disable the sensor and on the Stoich AFR table set cell 0.00 to 14.32227. You don't have to zero out the alcohol tables.

Thanks

[Road]

Can I just hit disable? The reason I ask is, I've got a Silverado that has an evap leak at the canister, I assume this is what's throwing off the VFF calculations causing the truck to think it has 44% ethanol in the fuel content raising stoich to 12.18 in CL. I'm just wanting some input from some of you who may have ran across this type situation before & if what I'm wanting to do will even work. Also do we have the ability with the scanner to do a fuel density reset?

The ethanol content gets skewed all the time causing this. You can do a fuel composition reset but it will do it again. Best to just disable it.

[10_SS]

The confusing part is my Silverado is always reading 9-10% Flex Fuel, which makes it's stoich target around 14.1, down from 14.67. If this is normal which people say it is, then why do they run non-85 cars at 14.67? Shouldn't they run them at 14.1?

[2xLS1]

The confusing part is my Silverado is always reading 9-10% Flex Fuel, which makes it's stoich target around 14.1, down from 14.67. If this is normal which people say it is, then why do they run non-85 cars at 14.67? Shouldn't they run them at 14.1?

Depends if you are running E10 or 100% gas. 100% gas is still available in many areas.

[2xLS1]

Can I just hit disable? The reason I ask is, I've got a Silverado that has an evap leak at the canister, I assume this is what's throwing off the VFF calculations causing the truck to think it has 44% ethanol in the fuel content raising stoich to 12.18 in CL. I'm just wanting some input from some of you who may have ran across this type situation before & if what I'm wanting to do will even work. Also do we have the ability with the scanner to do a fuel density reset?

I see this problem on many VFF trucks running 100% gas. I also see many VFF trucks that compute the alcohol content correctly. I have yet to find a reason for it. On the ones doing it wrong it always seems to be in the 35-40% alcohol content range. I probably see it more on 2011 and 2012 trucks but I've seen it on some 07-12 trucks at one time or another. Don't think I've seen it on a 13 but I see way more of the other year trucks. The only fix I've ever come up with is to disable the FF option.

[10_SS]

Depends if you are running E10 or 100% gas. 100% gas is still available in many areas.

My 2010 Camaro runs the same gas, it's stoich is 14.67. My Truck has the same gas from the same gas station and is at 14.1 cause it has a Flex Fuel sensor. Point is, this makes no sense. So if OP disables Flex Fuel then what does he tune for... 14.1, or 14.67. It seems like 14.1 would be best to tune for if you routinely get E10 fuel, and if you get E0 fuel then it will be a bit rich by ~4%. This way it wont be lean at WOT even if LTFT is pulling 4%. Or, do you want it to add 4% all the time since this carries over to PE (-LTFT does not). See my confusion? Yet Factory stock sets it at 14.67.

[HeavyChevy305]

I see this problem on many VFF trucks running 100% gas. I also see many VFF trucks that compute the alcohol content correctly. I have yet to find a reason for it. On the ones doing it wrong it always seems to be in the 35-40% alcohol content range. I probably see it more on 2011 and 2012 trucks but I've seen it on some 07-12 trucks at one time or another. Don't think I've seen it on a 13 but I see way more of the other year trucks. The only fix I've ever come up with is to disable the FF option.

This^^

My truck was constantly logging 17/20 even 30% alcohol while pumping 93 octane. I ended up just disabling the sensor and changing the commanded stoich AFR on cell 0.00 in the table to 14.32227. All pump gas contains up to 10% ethanol so to be safe I command that instead of the default 14.67xx.

[WS6HUMMER]

I see this problem on many VFF trucks running 100% gas. I also see many VFF trucks that compute the alcohol content correctly. I have yet to find a reason for it. On the ones doing it wrong it always seems to be in the 35-40% alcohol content range. I probably see it more on 2011 and 2012 trucks but I've seen it on some 07-12 trucks at one time or another. Don't think I've seen it on a 13 but I see way more of the other year trucks. The only fix I've ever come up with is to disable the FF option.

Yeah that's what I did and now it's commanding the correct stoich value in CL. I have another friend with a 10 that was complaining it was rich, nothing I could see in the tune & it's 100% stock. Logged it today and only showed 2% ethanol present which seemed legit to me, it has an evap code as well and I know the VFF uses the evap system so I went ahead and disabled the VFF. Have you ever seen the VFF system read the fuel composition wrong intermittently?

[2xLS1]

Have you ever seen the VFF system read the fuel composition wrong intermittently?

I don't own anything VFF to monitor long term. It's always been on tune customers trucks I see it.

[2xLS1]

All pump gas contains up to 10% ethanol.

There is still plenty of 100% gas to purchase here. I've even drawn fuel samples off trucks with the problem and tested it for alcohol and found none.