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Operating system update for e85 compatibility TSB

Discussion in 'Tech Info' started by Mudsport96, Mar 22, 2021.

Car Parts
  1. Mudsport96

    Mudsport96 Full Access Member

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    So i stumbled across this TSB for a software update for the Tahoe to improve e85 compatibility. Talked to the local dealership and they said they can do it, but it met the deadline long before i bought the rig. So if i want to do it, i have to pay shop rate for time, about a half hour.

    Has anybody here done the update?

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  2. Mudsport96

    Mudsport96 Full Access Member

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    Nobody? Well then.. I will be the Guinea pig lol. I plan on taking the Tahoe in next week and having the update done. I will run a few tanks and report back.
     
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  3. swathdiver

    swathdiver Full Access Member

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    Hadn't heard of this but am not on top with things in your generation. These motors do love to run E85, so a 1/2 shop time for the update is not a bad deal. Just make sure your sensor is good or all is for naught. We often burn a mixture in ours, about 16-20%, for best fuel economy and lowest cost to operate.
     
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  4. Mudsport96

    Mudsport96 Full Access Member

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    Mine is not a fan of e85, but perhaps that is because it hasnt had the update. On regular 87 it gets 17mpg to 19 mpg on the highway. On e85 the best i can get is 12.5 to 13. And at current prices its not worth it when you work out miles per dollar. I run it occasionally as a fuel system cleaner to flush the injectors but other than that i avoid it. Im hoping the new calibration could help bump it to maybe 14 and it would at least break even since e85 here is only like 10 cents cheaper than regular.
     
  5. Noggles

    Noggles TYF Newbie

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    E85 by nature will always have lower fuel economy even with a proper tune. It takes more of it to burn than regular gasoline does. Its benefits are mostly performance related, if the engine can utilize the higher octane and the cooling effect of ethanol burning, otherwise it's just a cheaper fuel with a lower fuel economy.
     
  6. Mudsport96

    Mudsport96 Full Access Member

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    Well the dealership finally was able to get the Tahoe in today to do the update. Ill know in a week or so if it did anything to help the mileage with e85
     
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  7. Fless

    Fless Full Access Member

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    With a scan tool you may want to monitor what the ethanol content is reading from time to time. If you're running E10 then it shouldn't go above 10% or so.

    Curious to know how it goes for you.
     
  8. gcronk3

    gcronk3 TYF Newbie

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    How much did they charge you to this update?
     
  9. Mudsport96

    Mudsport96 Full Access Member

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    Something like 62 bucks after tax.

    Going to be another couple weeks to see how it affects the mileage. My wife just put half a tank of 87 in so will have to run that out and start over again.
     
  10. Mudsport96

    Mudsport96 Full Access Member

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    Well I cant seem to get it through to my wife to use only e85 when she fills up so i can see how the new program does.

    However, on a straight dose of 87 octane she seems to do much better.
    Getting 20 mpg at 70 miles per hour.
    So thats a solid 1 mpg above where it was before, and that was pulling a slight (almost negligible) uphill grade.


    If i can get a solid full tank of e85 for 2 weeks ill get back with that info.
     

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