I'll be filling up on Saturday -- provided the pump has E85 -- after a run up to the north side of the city, so I'll be checking percentages before and after.
Ethanol percentage flex fuel
- Thread starter wsteele
- Start date
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gooffeyguy
Tom
I have noticed in the past when running E10 my % has read 7% and even read 3% for one tank.
I think if you're having a problem with it not calculating accurately with a known/tested fuel, then something that's involved in the calculation isn't working correctly.
Oxygen sensors, MAF sensor, knock sensor maybe?, or even in the ECM calibration. Have you checked to see if you have the latest calibration?
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Since I started watching this stuff, mine has never accurately calculated the E% when running E10 fuels (or 0% for that matter). It has gotten as high as 38% (when I first started to investigate it as warm ups when running open loop got downright smelly and was beginning to worry me that my cats would be negatively affected).
As I posted earlier in the thread, when filling with 0% and resetting with the Tech 2, it stayed down at 3% (where the Tech 2 sets it). But the next time I fueled with E10 (actual measured E% of 6%), it hopped right back up into the high teens.
Clearly something is not working correctly. I had high hopes when reading the explanation Chris (@iamdub) posted about how the virtual sensor E calc works, that maybe my Canister Purge Valve was not operating properly as it is the only thing called out in that explanation that might affect the calc, other than O2 and trim input. Coincidentally, my Evap monitor also never completed, so again, high hopes. Unfortunately, I replaced the Canister Purge Valve with a new OE unit and also replaced the cap with an OE cap and while my Evap monitor completes now, E% calcs are still screwy.
I replaced all four O2 sensors with OE units recently as the ones in the truck were original and felt I was probably living on borrowed time with them anyway. I did it more because I wanted to choose when I did it, versus any indication any of them weren't functioning properly. Clearly, that was also not the problem.
I do have the latest calibration, something I ran down right away at the suggestion of Steve (@Fless).
As I have posted a few times in my lower moments on this issue, I suspect I may never know why my Virtual Sensor doesn't work and may never get it to function properly. Like so many things in life, it is really hard to fix something that is not clearly broken.
As I have posted a few times on this and predecessor threads, I feel like I may end up just resetting it with the Tech 2 anytime it starts to creep up into E% ranges that cause a very rich open loop condition and call it good. I likely will never be running E85 normally as it just isn't competitive price wise at the station I can buy it at here, so I know my percentage will always be 10% or less.
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swathdiver
Full Access Member
I got my last backwards. The kids have Apple phones and tell me that Torque is not available. So they have Dash Command and on that one they cannot pull up alcohol, so they tell me.
if this is true should the hybrid be able to run E85 as well? it has the same injectors as the flex models
kbuskill
***CAUTION*** I do my own stunts!
I have no idea, as I am not familiar with the Hybrid Tahoes... does it have a yellow gas cap???
kbuskill
***CAUTION*** I do my own stunts!
If that app allows custom PIDs then they should still be able to enter the information and get it to work.
I don't have any Apple phones because I hate them and prefer Android so I'm not exactly sure what is or isn't available for them.
The sure way to find out is too run the tank down real low and then fill it with E85. Clearly you will have the volumetric capacity with the injectors. Does Circle K even sell E85?
the only station with E85 is chevron down the street 3-4 miles away
it only has 30 pound injectors not sure if this is enough
gooffeyguy
Tom
At 80% duty cycle they'll only support about 290hp on E85
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iamdub
Full Access Member
It's not just injector volume that matters. You need the FF fuel pump that can push the extra volume while maintaining necessary pressures. The fuel system also has to be made of materials impervious to alcohol. Although, by now, pretty much all FF and non-FF systems are.
In short, the LFA is not FlexFuel capable.
looks like the LZ1 has 36 lb injectors is that enough?
swathdiver
Full Access Member
The LFA is not a FlexFuel motor, the LZ1, which replaced the LFA in 2010 is a FlexFuel engine. You're not supposed to run more than E15 through a non-FlexFuel engine.
Me neither, don't like them or the thinking behind them.
Filled mine up today from nearly empty, 23.7 gallons E85 @$2.399. The fuel light came on about 2 miles before the fuel stop. Ethanol composition went up from 70% to 78%.
Makes sense, summer is coming.
Seems a real sensor does make a difference when it comes to accuracy.
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So I thought I would finish this thread with a conclusion that I expect I won’t be successful finding the root cause of my Virtual Ethanol sensor errors. Everything in the flex fuel and emissions area seems to be working fine, all the while my “sensor” can’t seem to figure out what gas I have in the tank.
My guess right now is a combination of factors between maybe less than perfect coding of the algorithms that do the calculation, perhaps with some tolerance stacking in the systems the Virtual Sensor uses for input, leads to it miscalculating the Ethanol amount.
So far, the error is always on the side of the sensor assuming I have more ethanol in the tank than it does, so the error appears to always on the rich side, which probably is a good thing as far as basic function of the engine in open loop (cold starts).
I will continue to try different fuels and test these to get base lines of what is actually in the tank, versus what the Virtual Sensor thinks is in the tank, but as I said, I don’t expect any progress beyond my edification.
I will continue to use the Tech 2 to reset the ethanol content when things get out of hand and my cold starts begin to get overly rich but I suspect that will be the extent of my ability to get things in line.
Sorry I couldn’t solve this issue.
My guess right now is a combination of factors between maybe less than perfect coding of the algorithms that do the calculation, perhaps with some tolerance stacking in the systems the Virtual Sensor uses for input, leads to it miscalculating the Ethanol amount.
So far, the error is always on the side of the sensor assuming I have more ethanol in the tank than it does, so the error appears to always on the rich side, which probably is a good thing as far as basic function of the engine in open loop (cold starts).
I will continue to try different fuels and test these to get base lines of what is actually in the tank, versus what the Virtual Sensor thinks is in the tank, but as I said, I don’t expect any progress beyond my edification.
I will continue to use the Tech 2 to reset the ethanol content when things get out of hand and my cold starts begin to get overly rich but I suspect that will be the extent of my ability to get things in line.
Sorry I couldn’t solve this issue.
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swathdiver
Full Access Member
Consider taking a Snapshot and making a video of it on the TIS2000 software and then upload it so we can all look at the data, Fuel Trims, Injector Pulses, Alcohol, etc.
Our computer systems are set up to easily add a real sensor and kits are sold for this.
I don’t have the TIS2000 SW, my PC is Windows 10 and the Mac is my main computer, so nothing that is compatible as I am setup now. I can take a video of the Tech 2 screens though. I have them pretty memorized by now.
Since I have the Tech 2, I think I will skip installing an aftermarket kit with a real sensor. The only problem this condition poses is it wanting to run really rich on cold starts and then only when it has gotten way off. The worst error I have seen was 38% Ethanol when I had E10 in the tank. That got a little smelly until it got to closed loop.
swathdiver
Full Access Member
I don’t have the TIS2000 SW, my PC is Windows 10 and the Mac is my main computer, so nothing that is compatible as I am setup now. I can take a video of the Tech 2 screens though. I have them pretty memorized by now.
Since I have the Tech 2, I think I will skip installing an aftermarket kit with a real sensor. The only problem this condition poses is it wanting to run really rich on cold starts and then only when it has gotten way off. The worst error I have seen was 38% Ethanol when I had E10 in the tank. That got a little smelly until it got to closed loop.
Just a thought Bill, have you checked the software version installed in your truck against the TIS2WEB website to see if there was an update that might encompass the issues you are having?
