swathdiver
Full Access Member
Well, as soon as the system detects a refueling event it's going to begin recalculating anyway so maybe that's why they didn't allow for that.
Ethanol percentage flex fuel
- Thread starter wsteele
- Start date
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Well, as soon as the system detects a refueling event it's going to begin recalculating anyway so maybe that's why they didn't allow for that.
It just seems like you would want to be able to set it to where you know it is, versus having to know you have less than 10% in the tank before performing a reset. I guess the only real glitch is when you reset it and have E85 in the tank, with the risk of it not running at all to be able to get it to closed loop and start correcting on the fly.
iamdub
Full Access Member
Are you going by the advertised Ethanol percentage? This can vary wildly, especially at an "E85" pump. The only way to know your actual alcohol content is to measure it. I have this to measure it: https://www.amazon.com/Etched-Ethanol-Content-Tester-Gasoline/dp/B07NMV8WGP
As James mentioned, it takes at least seven miles of driving (mainly cruising) for the system to "accurately" calculate the content. Hard throttle (in PE) or stopping with engine off can really throw off its calculations.
As James mentioned, it takes at least seven miles of driving (mainly cruising) for the system to "accurately" calculate the content. Hard throttle (in PE) or stopping with engine off can really throw off its calculations.
gooffeyguy
Tom
E85 isn't always (and hardly ever) 85%. It can range from like 55-83%, or something like that.
Regular (E10) isn't always 10% either. On the pump it says it may contain up to 10%.
I got gas today. Second time since I've been back from the trip to NOLA, in which I ran a few tanks of ExxonMobil 93. Last time I fueled up was with e85 and my % before filling today was 55.
After filling up with 24 gallons of E85 (@$2.09), I watched the % on the Torque app on my phone. It dropped to 40 for a few minutes, then up to 60 for a minute, then to 55, then up to 66, and I think it finally settled at 69%. There might have been a couple #s it jumped to but I didn't catch due to having to drive.... lol.
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Regular (E10) isn't always 10% either. On the pump it says it may contain up to 10%.
I got gas today. Second time since I've been back from the trip to NOLA, in which I ran a few tanks of ExxonMobil 93. Last time I fueled up was with e85 and my % before filling today was 55.
After filling up with 24 gallons of E85 (@$2.09), I watched the % on the Torque app on my phone. It dropped to 40 for a few minutes, then up to 60 for a minute, then to 55, then up to 66, and I think it finally settled at 69%. There might have been a couple #s it jumped to but I didn't catch due to having to drive.... lol.
Sent from my SM-G930V using Tapatalk
The gas I have been using for quite a while (not counting the 0% Ethanol I used for the reset test) is Costco (advertised as less than 10% Ethanol). My Yukon has @calculated” high 30’s% Ethanol for quite a while with this gas.
When I did the test with the 0% and the reset with the Tech2, it stayed at the 3% reset number for the whole tank.
For whatever reason, a little Ethanol content really seems to fool with the calculation.
My assumption is something sensor wise is causing my truck to misread how much Ethanol is in the gas.
iamdub
Full Access Member
Such as the lack of a sensor. lol
Right, so what it is using to calculate it must be sending bad data. Or Costco is putting 30+% Ethanol in their <10% Ethanol gas (pretty unlikely).
My assumption was my PCM was calculating an incorrect Ethanol content due to really tired (original) O2 sensors. I changed out all 4 and the exact same results occur. The Ethanol content calculation just seems to get higher and higher, tank to tank of the Costco <10% Ethanol (with some Shell and Chevron <10% Ethanol thrown in).
When I found the reset function on the Tech 2 I was excited as I could see if running 0% Ethanol would still yield an ever creeping higher Ethanol calculation (and seemingly ever richer open loop mixture). In fact, when I pumped a tank full of the 0% and reset it, it stayed right at 3.14% calculated content through the whole tank (the number the Tech 2 reset it to).
As soon as I started using the Costco gas again, it started moving up. I have used about a quarter of a tank of the latest fill of Costco Regular and it finished at 17% today. I suspect before I get to refill time it will be over 30% calculated.
I wish I knew what that algorithm looked like, what sensor input it relied on, to calculate the %. Then I would at least know what I might try to change out, clean, etc.
This situation cries out for an ethanol percentage test at the pump (@iamdub posted a tester), midway during the fill-up. That minimizes errors from fuel left in the hose from the last person who fueled up, with possibly different fuel.
Then a similar test perhaps halfway through the tank, taken from the fuel rail. That would verify what's going in and what's really in the tank.
IIRC the ethanol is added separately to the station's tanks by the tanker driver, and that could cause varying percentages. Hard to know what's going on without testing.
Then a similar test perhaps halfway through the tank, taken from the fuel rail. That would verify what's going in and what's really in the tank.
IIRC the ethanol is added separately to the station's tanks by the tanker driver, and that could cause varying percentages. Hard to know what's going on without testing.
Perhaps you guys are right. It just seems kind of far fetched that I would be getting 30+% Ethanol in gas that each pump advertises boldly (less than 10% Ethanol), but I guess it would be a profit adder to the distributor if they decided to just keep adding Ethanol to the tank. It is easy enough to test. I will post the results.
