E85 in the 4.3 Ecotec3, Yes or No?

[Fire2968]

Vehicles with a yellow fuel cap can use either unleaded gasoline or fuel containing up to 85% ethanol (E85). All other vehicles should use only the unleaded gasoline as described in Fuel

 

The use of E85 or FlexFuel is encouraged when the vehicle is designed to use it. E85 or FlexFuel is made from renewable sources. To help locate fuel stations that carry E85 or FlexFuel, the U.S. Department of Energy has an alternative fuels website. See www.afdc.energy.gov/afdc/locator/ stations. E85 or FlexFuel should meet ASTM Specification D 5798 or CAN/ CGSB–3.512 in Canada. Do not use the fuel if the ethanol content is greater than 85%. Fuel mixtures that do not meet ASTM or CGSB specifications can affect driveability and could cause the malfunction indicator lamp to come on. For the 6.0L V8 engine, after refueling, the vehicle calculates the composition of the fuel. It is not recommended to repeatedly switch between fuels. If fuels are switched frequently, add as much fuel as possible and do not add less than 11 L (3 gal) when refueling. Drive at least 11 km (7 mi) immediately after refueling to allow the vehicle to adapt to the change in ethanol concentration. Because E85 or FlexFuel has less energy per liter (gallon) than gasoline, the vehicle will need to be refilled more often.

[Donstar]

20 hours ago, Frank-OH said:

Grats on the rig my friend! She is sharp!! I can't speak for the 4.3 performance per say but can say if you plan on using your truck for a truck, your gonna wish you had went for the 5.3. 

The op's 4.3 is an exceptionally capable motor and can out perform many of the V8's that pre-date this version.  I most recently came from a vortec 5.3 to a ecotec 4.3 and the transition was seamless.  The new ecotec 5.3 is a more powerful engine but this doesn't make the 4.3 less capable as a truck engine.

[tim5779]

29 minutes ago, Fire2968 said:

From the manual of a 2017 GMC Sierra 5.3

 

If the vehicle has a yellow sticker on the fuel door, E85 or FlexFuel can be used. (See E85 or FlexFuel section)

 

Except the 6.2L engine, use regular unleaded gasoline meeting ASTM specification D4841 with a posted octane rating of 87 or higher. Do not use gasoline with a posted octane rating of less than 87, as this may cause engine knock and will lower fuel economy.

 

For the 6.2L engine, premium unleaded gasoline meting ASTM specification D4841 with a posted octane rating of 93 is highly recommended for best performance and fuel economy. Unleaded gasoline with an octane rrated as low as 87 can be used. Using unleaded gasoline rated below 93 octane, however, will lead to reduced acceleration and fuel economy.  

 

CAUTION:

 

Do not use fuels with any of the following conditions; doing so may damage the vehicle and void its warranty:

 

 - For vehicles which are not FlexFuel, fuel labeled greater than 15% ethanol by volume, such as mid-level ethanol blends (16-50% ethanol), E85, or FlexFuel.

 

ha ha...here's a snapshot of mine...same year.  Not sure why they're different.  Notice it does say "the use of E85 or Flex fuel is encouraged"

[Fire2968]

Just now, tim5779 said:

ha ha...here's a snapshot of mine...same year.  Not sure why they're different.  Notice it does say "the use of E85 or Flex fuel is encouraged"

Yours is from the next page of the manual.

Thats my following post after the one your quoted. That is IF it can run E85

[swathdiver]

1 hour ago, tim5779 said:

...BUT, it doesn't really matter cause you guys have made up my mind.  There's alot of real world data here, and some damn good experienced opinions as well.  As soon as she hits "E" I'm gonna fill her up with E85 and see what she does.  I'm thinking 15+ horse and 25+ ft/lbs will definitely be blatantly obvious.

GM does have published information on the horsepower and torque increases from using E85.  Gains are less than what your surmised but it's definitely noticeable.  Don't worry about running it down to empty, just start logging your specs and you'll start seeing even greater improvements by the third tank.

 

I first started using E85 during the approach of a hurricane, everyone was waiting in line for gas and the nobody was lined up at the yellow pump.  That's when I remembered my yellow gas cap and took on a tank and it was great.  Tried it off and on for a time but have been running E85 since October.  My truck was rated by GM to get about 11mpg city and 14 highway and my numbers are similar on it.  On pump gas it's not much better but I have a bad cat that will get replaced soon.

[tim5779]

56 minutes ago, swathdiver said:

GM does have published information on the horsepower and torque increases from using E85.  Gains are less than what your surmised but it's definitely noticeable.  Don't worry about running it down to empty, just start logging your specs and you'll start seeing even greater improvements by the third tank.

 

I first started using E85 during the approach of a hurricane, everyone was waiting in line for gas and the nobody was lined up at the yellow pump.  That's when I remembered my yellow gas cap and took on a tank and it was great.  Tried it off and on for a time but have been running E85 since October.  My truck was rated by GM to get about 11mpg city and 14 highway and my numbers are similar on it.  On pump gas it's not much better but I have a bad cat that will get replaced soon.

I thought those were the GM specs?  I read 285hp jumps to 297 and 305 ft/lbs jumps to 330?  Those are pretty impressive numbers for a V6!

[swathdiver]

Well Tim, maybe they are.  Never saw them for a V6, just for my old LC9 and the L83.  

[DONWT15]

4 hours ago, tim5779 said:

I thought those were the GM specs?  I read 285hp jumps to 297 and 305 ft/lbs jumps to 330?  Those are pretty impressive numbers for a V6!

Those are the GM specs. The only negative is your mileage will drop. You won't know how much until you try it. If you decide it's too much, you can always go back. But overall it won't hurt your truck.

[swathdiver]

It's only a negative if you don't want to refuel often, the cost per mile is often much less.

[Perseus]

I have been a 4.3 nut swinger since I had one for a loaner in early '14. I ended up buying a crew cab short box. I have loved this motor since day one. Currently 65k and I go back and forth between 87 and e85. Usually run E in the winter as I idle ALOT. my cost per mile is down but I do fill up more often. I drive like a much older man that I am so I can't speak to it's performance. However I will say I've maxed payload by a few hundred pounds and I've towed smaller cars with this truck and it continues to impress me. Let the haters hate the ecotec3 4.3 might be one of GMs current best kept secrets. (I would like to see it behind the 10speed tho)

Sent from my SM-J727V using Tapatalk

[bgbdwlf2500]

11 hours ago, tim5779 said:

I thought those were the GM specs?  I read 285hp jumps to 297 and 305 ft/lbs jumps to 330?  Those are pretty impressive numbers for a V6!

it is definitely noticeable, whatever the numbers are. I think its pretty cool GM created a secondary "tune" when the truck sees E85. Its not going to hurt to fill it now, wherever you are in the tank of fuel, just make sure to do the refueling event. You will notice a difference as the alcohol ratio is going to climb pretty drastically especially if you are at a half a tank or lower. Your next fill up should give you the full power depending on what the minimum alcohol content is where you are. Here in SC the pump says minimum 70% and ive seen the reading at 76 and 80% on one of the inexpensive OBD 2 scanners. Your mileage will fall pretty drastically though especially if you have any stop and go. As I said in an earlier post, I'm down to 290 miles on a tank on E85, I was around 400 on 87 at one point

[tim5779]

8 minutes ago, bgbdwlf2500 said:

it is definitely noticeable, whatever the numbers are. I think its pretty cool GM created a secondary "tune" when the truck sees E85. Its not going to hurt to fill it now, wherever you are in the tank of fuel, just make sure to do the refueling event. You will notice a difference as the alcohol ratio is going to climb pretty drastically especially if you are at a half a tank or lower. Your next fill up should give you the full power depending on what the minimum alcohol content is where you are. Here in SC the pump says minimum 70% and ive seen the reading at 76 and 80% on one of the inexpensive OBD 2 scanners. Your mileage will fall pretty drastically though especially if you have any stop and go. As I said in an earlier post, I'm down to 290 miles on a tank on E85, I was around 400 on 87 at one point

I keep hearing people mention "refueling event"?  Is there something I manually need to do?  I thought you just filled up with E85 and the truck did the rest?

[bgbdwlf2500]

Just now, tim5779 said:

I keep hearing people mention "refueling event"?  Is there something I manually need to do?  I thought you just filled up with E85 and the truck did the rest?

it does, that's just what GM calls it. I could be wrong on this but I think adding enough fuel to the truck forces an alcohol content check

[tim5779]

2 minutes ago, bgbdwlf2500 said:

it does, that's just what GM calls it. I could be wrong on this but I think adding enough fuel to the truck forces an alcohol content check

Nevermind, I found a thread on here.  A refueling event consists of:

 

- Truck key must be turned to OFF during refuel

- No less than 3 gallons

- Allow 7 miles for truck to make calcs

 

Good to know.

[bgbdwlf2500]

3 minutes ago, tim5779 said:

Nevermind, I found a thread on here.  A refueling event consists of:

 

- Truck key must be turned to OFF during refuel

- No less than 3 gallons

- Allow 7 miles for truck to make calcs

 

Good to know.

it would be in your owners manual as well. I think any less than 3 gallons they figure it wont change the ethanol content enough to matter. after 3 gallons when you restart the truck senses the added fuel and goes ahead with the calculation. I had that hard start condition that one time when it got stuck on e85 and I had filled it up with 87 so the computer was seeing 80% alcohol when it really was at 10 or so. Thinking back I set the truck back to stock with my tuner so I may have had the key on while refueling and that could have caused the issue