I have a flexfuel 07 lt, and now that the e85 prices are near 2.99, while regular is 3.99 here in crook county, il (chicagoland) it might start making sense and cents to switch. With the projected 25% decrease in efficiency, and the 25% savings on gas its coming to be a wash, except for the more frequent gas station trips. Where I live, every other gas station has e85, so its not a big deal, just wanted to get feedback on starting using e85 at 80K
-
If you currently own, previously owned or want to own an Avalanche, we welcome you to become a member today. Membership is FREE, register now!
E85 on higher mileage (80K) 5.3
- Thread starter tweak302
- Start date
krazycarguy
Full Member
I did the math about a year ago, E85 has to be at least a dollar cheaper to make it worth while. In terms of switching now, no big deal. Just remember, there is no fuel composition sensor, the ecm calculates it. So when you fill up, Drive it for at least 15 min. Other wise youll end up with fuel trim codes.
Thats exatly why im thinking about it. The e85 is 25% cheaper, and with the economy being 25% worse, its a wash, so im thinking about giving it a dable. I have read in the past that higher ethanol content has a tendency to dry out some components in the fuel system, and if it hasn't been used for such a long time ( 7 years ) to not start now.
krazycarguy
Full Member
all the fuel component were designed to run e85. It shouldnt matter how old they are.
My girlfriend has a '13 Silverado and we have been putting E85 in her truck since she had been driving the 40 miles one way to see me.. I have a station near me that does $1 less per gallon. Her truck has been showing about a 10% drop in milage per tank so I don't know if E85 is that much less... But then again that is with mostly highway driving.
Her truck used to get 330-340 per tank and now she gets 300-310 per tank.
So I would say try it for a couple tanks worth and see what you get. I would do it by the tankful and compare with similar driving.
Rodney
Her truck used to get 330-340 per tank and now she gets 300-310 per tank.
So I would say try it for a couple tanks worth and see what you get. I would do it by the tankful and compare with similar driving.
Rodney
krazycarguy
Full Member
E85 is less potent than gas. It take more to make the same amount of power. So what you expirienced is normal. Thats why e85 has to be at least a dollar a gallon cheaper to be worth it.
It's still cheap racing gas. If you have a tune that requires premium tune compare it to the price of premium, obviously, for the economics. I personally quit using it a few years ago because of some odd starting issues.
I did the E85 comparison on both my 05 and my 08, running 3 full tanks through and checking the results (both w/ 5.3L motors). When I had my 05, I averaged 14.9MPG on 87 octane pump gas, I averaged 13.0 on E85, about 14.5% worse fuel mileage
On my 08, I average 15.2MPG on pump gas and average 13.4 on E85 . about 13.4% worse fuel mileage.
The E85 here, fluctuates from 10-17% less in cost than 87 octane. Today 87 was $3.88/gal and E85 was 3.42/gal, only 12% less, so I got 87.
I switch back and forth, I just pull the calculator out on my phone and do the quick math each time I pull in to fill up, if the E85 is 13.5% or more cheaper, I get that, if not, then I get gas.
If you can get E85 25% cheaper than gas, I would def. give it a shot, just check your mileage and make an educated decision on weather or not the econimics of it work out in your favor.
I turned over 94,000 miles today and have had no problems related to switching back and forth and I bought it w/ 34,000 mi and have been using E85 w/ varied frequency since I bought it. I never encountered any problems using it in my Sillverado or my 05 Av either
I'm not sure 15 min. is necessary, you may have had a fluke instance. The only time I have ever had the code pop up was when I only went across the street for a burrito.(<1/4 mi) I often full up at the Sheetz about 1 mile from my house and go directly home and I have no problems.
On my 08, I average 15.2MPG on pump gas and average 13.4 on E85 . about 13.4% worse fuel mileage.
The E85 here, fluctuates from 10-17% less in cost than 87 octane. Today 87 was $3.88/gal and E85 was 3.42/gal, only 12% less, so I got 87.
I switch back and forth, I just pull the calculator out on my phone and do the quick math each time I pull in to fill up, if the E85 is 13.5% or more cheaper, I get that, if not, then I get gas.
tweak302 said:
If you can get E85 25% cheaper than gas, I would def. give it a shot, just check your mileage and make an educated decision on weather or not the econimics of it work out in your favor.
I turned over 94,000 miles today and have had no problems related to switching back and forth and I bought it w/ 34,000 mi and have been using E85 w/ varied frequency since I bought it. I never encountered any problems using it in my Sillverado or my 05 Av either
krazycarguy said:
I'm not sure 15 min. is necessary, you may have had a fluke instance. The only time I have ever had the code pop up was when I only went across the street for a burrito.(<1/4 mi) I often full up at the Sheetz about 1 mile from my house and go directly home and I have no problems.
krazycarguy
Full Member
The 15 min is what GM says is the required time to learn the new fuel comp. You also need to put more than 3 gallons in, or it wont see it as a refueling event.
krazycarguy
Full Member
Fuel System Overview
The Fuel System is a returnless on-demand design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
An electric turbine style fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
E85 Flex Fuel Description
E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.
The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.
Air-fuel ratios and the corresponding ethanol percentage are updated following each purge-off sequence. The fuel alcohol content percentage value can be read on a scan tool.
When an E85 compatible vehicle is built, an ECM or PCM replaced, or if the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10 percent or less ethanol content.
A minimum of 11 liters (3 gallons) must be put in the tank in order for the vehicle to recognize a re-fueling event. It is not necessary to turn the ignition OFF in order to have the re-fueling event recognized, however local safety regulations should be followed.
After the re-fueling event, the system registers the amount of fuel that was added, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines if the fuel added was either ASTM Gasoline or ASTM E85. Based on that determination, the system adjusts to the expected alcohol mix in the fuel tank, and then the fuel trim and O2 sensor activity fine tunes the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or E85 to gasoline, can result in driveability symptoms due to the inability of the system to adjust for fuel composition by not attaining closed loop operation.
Switching Between Gasoline and E85
No special precautions need to be taken when switching back and forth between gasoline and E85 other than re-fueling events must be 11 liters (3 gallons) or greater, and the vehicle must remain in closed loop long enough, usually by the time the engine has maintained full operating temperature, to calculate the composition of the new blend in the tank.
The Fuel System is a returnless on-demand design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
An electric turbine style fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
E85 Flex Fuel Description
E85 compatible vehicles no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle calculates the alcohol content of the fuel through measured adjustments.
The ethanol calculation occurs with the engine running after a refueling event has been detected via a measured change in the fuel level sender output. The virtual flex fuel sensor (V-FFS) algorithm temporarily closes the canister purge valve for a few seconds and monitors information from the closed loop fuel trim system to calculate the ethanol content. This logic executes several times until the ethanol calculation is deemed to be stable. This may take several minutes under low fuel flow conditions such as idle, or a shorter time during higher fuel flow, off-idle conditions.
Air-fuel ratios and the corresponding ethanol percentage are updated following each purge-off sequence. The fuel alcohol content percentage value can be read on a scan tool.
When an E85 compatible vehicle is built, an ECM or PCM replaced, or if the learned alcohol content has been reset with a scan tool the fuel system will need to contain ASTM gasoline with 10 percent or less ethanol content.
A minimum of 11 liters (3 gallons) must be put in the tank in order for the vehicle to recognize a re-fueling event. It is not necessary to turn the ignition OFF in order to have the re-fueling event recognized, however local safety regulations should be followed.
After the re-fueling event, the system registers the amount of fuel that was added, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines if the fuel added was either ASTM Gasoline or ASTM E85. Based on that determination, the system adjusts to the expected alcohol mix in the fuel tank, and then the fuel trim and O2 sensor activity fine tunes the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or E85 to gasoline, can result in driveability symptoms due to the inability of the system to adjust for fuel composition by not attaining closed loop operation.
Switching Between Gasoline and E85
No special precautions need to be taken when switching back and forth between gasoline and E85 other than re-fueling events must be 11 liters (3 gallons) or greater, and the vehicle must remain in closed loop long enough, usually by the time the engine has maintained full operating temperature, to calculate the composition of the new blend in the tank.
Allrighty, thanks for the input. Let the Experiment begin.
6/13/14 27.6 Gallons of e85 filled at 2.99$ (4.08 for regular)
I plan on doing 3-4 tanks, so about 1000 miles to get the average over the next month or so (provided the $ difference stays the same)
On a side note, with my style of driving, for 50/50 city/hwy mix, my average mpgs are 13.5-14 according to the trip computer, and about the same from the actual calculations at fillup vs trip odometer. After filling up today and resetting the display i averaged 9.5 mpg to work, which is not the 15-25 % difference, but rather 30%.. Long story short, i gotta keep the mpgs over 9.9 for this to be even, and probably closer to 11 or 12 for there to be a faint twinkle of hope that im gonna continue using this crap.
6/13/14 27.6 Gallons of e85 filled at 2.99$ (4.08 for regular)
I plan on doing 3-4 tanks, so about 1000 miles to get the average over the next month or so (provided the $ difference stays the same)
On a side note, with my style of driving, for 50/50 city/hwy mix, my average mpgs are 13.5-14 according to the trip computer, and about the same from the actual calculations at fillup vs trip odometer. After filling up today and resetting the display i averaged 9.5 mpg to work, which is not the 15-25 % difference, but rather 30%.. Long story short, i gotta keep the mpgs over 9.9 for this to be even, and probably closer to 11 or 12 for there to be a faint twinkle of hope that im gonna continue using this crap.
25% min/best to 30% is the norm.
So After the first full tank i managed to get a whopppppping 10.5 MPG per the display. My calculation was less optimistic (300 Miles on 29.6 gallons), as that came to 10.2 MPG. Gas Is still at 2.99 for e85 and 4.03 for the 87, so i filled up again, and the experiment contunues.
NOTE: The truck feels like crap. You can tell the difference in how it runs on the garbage out of the yellow nozzle.
NOTE: The truck feels like crap. You can tell the difference in how it runs on the garbage out of the yellow nozzle.
krazycarguy
Full Member
My truck ran fine on e85.
Captain
Full Member
I'm in SW Chicago , durning the winter I run e85 since I let my truck warm up and it's cheaper to use the 85. For summer I run 87
Just finished running 2 full tanks of E85 to recheck my calculations after see others were getting much worse numbers than myself. I ran my tank of 87 down to empty(needle on empty and fuel range reading on low)
I pumped 59.521 total gallons and ran 773.3 miles. 13.0 average
E85 here is $3.29 while pump gas 87 is $3.89.
I'm wondering if there are different grades of E85 as the price here is significantly more than the 2.99 tweak is paying, and my pump 87 is actually cheaper.
I don't notice any difference. Runs exactly the same for me.
I pumped 59.521 total gallons and ran 773.3 miles. 13.0 average
E85 here is $3.29 while pump gas 87 is $3.89.
I'm wondering if there are different grades of E85 as the price here is significantly more than the 2.99 tweak is paying, and my pump 87 is actually cheaper.
tweak302 said:
I don't notice any difference. Runs exactly the same for me.