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Discussion Starter · #1 ·
Hey everbody, I've been a guest for about a year but just became a member yesterday. I've come here several times because of issues with my 2012 5.7 flexfuel Crew Max 4wd and I have found this site to be a great resource of information. I've read posts about gas milage and I know the 5.7 is not an economical engine but I'm only getting 8-9 miles city and I have never got better than 15 highway. I drive very conservative no quick take offs and speed limit on highways. No mods, yet, and stock 18" wheels. I've already had to have my computer reset twice because it was misreading the fuel as ethanol(E85). Dealer kept insisting that it was my fault, that I had put in E85 and I would have to pay them $90.00 an hour to drain my tank. Excuse me, but it is a flexfuel engine is it not and besides I do not use E85, period. Thanks to this site I was able discuss that particular problem with some knowledge of the situation. I'm at my wits end with this truck, my dream truck has turned into a nightmare. Any information or suggestions will be appreciated.
 

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Seems low, but am not sure it's that low. How fast do you drive? What tires are you running, and at what psi? What else do you have in the truck besides yourself? Did you install a cap on the bed? How many miles on the truck?

How do you know the ECU registered the fuel as E85? I wonder if there is a sensor off--I'm guessing it "knows" E85 usage going by reading the O2 sensors and realizing the air/fuel maps is off, not by any particular ethanol sensor. It could be a bad O2 sensor.
 

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8 mpg can actually be reasonable in the city. 15 on the highway is low but not ridiculously low. If you cruise at 75 mph or above it sounds about right. If you cruise at 60 or 65 mph it is a bit low.

Use your insantaneous display. It is a great tool for teaching you how to optimize MPG. If you are driving like a snail in the city that could hurt you. You do better when you get up to speed with reasonable quickness and cruise for a maximum amount of time at little to no throttle than when you spend 80% of your time between lights accelerating and the other 20% braking.


Other factors that play a part:

Terrain

Weather

Seasonal ethanol mixes

Excess stuff you keep in the truck
 

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I think that's unusually low. Unless he's towing a 8k trailer around the city. I get 15.1mpg city on my 2007 and like 20-21 hwy...

He's getting like hummer h1 gas mileage....
 

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It sounds like part of your woes is a prick head, dumb ass dealer.
If another dealer is an option, explore it.

I don't have the flex fuel engine, but it would have to deal with varying amouts of E85/gas. If you can go with straight DDJ (dead dino juice, aka gas) do it. Your mileage should improve using it, especially since the summer blend fuel is now available (my mileage has improved). It's worth pointing out mileage will go down during the winter/colder months.
 

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Discussion Starter · #6 · (Edited)
Thanks to this site and great dealer service the second time in for the same issue i've become well versed on this and instructed another dealer how to fix the issue the third time around after they argued with me that i was running to much alcohol in my gas, which I'm not, but isn't it flexfuel engine anyway. I have only used E85 once and it was early after purchased with no issues but I generally run 85-87. As I said I drive conservatively, no quick starts and 65-70 highway unless posted higher. My wheels are stock 18" 275/65/18 nitrogen filled dueler ht. I don't know if the ecu misreading s are causing poor mileage but it supposedly is reset to original settings. Sad thing, this is just one of several issues I'm having with this truck. I'm considering pushing the lemon law. Thanks for the replies.
 
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Discussion Starter · #7 ·
Not towing nor hauling anything except for my girlfriend and her 8lb "chi weenie" dog.
 

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Sorry to hear about your woes. I suspect the dealer will do nothing, as the mpg is within the EPA estimates. I would track mpg the old fashioned way, paper and pencil, just to verify the computer though. If nothing else it may help with the lemon law bit, if you have data showing low mpg.
 

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8-9 seems too low, try resetting the ECU (disconnect the negative battery cable for 10-20 mins).

It will learn driving habits again, but might help ya, worth a shot.

As supton suggested, manually track your mpg, I use an app on my phone for every fill up - have used it as long as I've owned my truck.
 

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I agree - reset ecu and check tire pressure and try getting fuel from another station. I've read some others having same issue and toyota is working on a fix - seems sensor in fuel tank is not reading properly throwing the ecu into e85 mode and that kills HP's and MPG's. E 85 another waste
 

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See my thread(s) about FlexFuel and E85 sensor problems. Sounds like your rig is suffering from it, because low MPG is a dead giveaway, as well as other performance issues.

Good news is, just this weekend Toyota came up with a re-flash that should correct the problem. I was the first at my dealership to get it done. Here's hoping it works out.

.....and your dealer does sound like a tool.
 

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Dam that sucks man. I thought my mileage was bad. I get like 14mpg around town and like 18mpg highway. I drive like an old man though.

Once I get my supercharger and drop the truck (will go way down lol).

Good luck.
 

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Unfortunately, I have a FlexFuel 5.7 2013 CM and I'm getting 8.2-8.7 mpg around town also. I'd say that I drive conservatively also. A fair number of stop signs and an average running speed of 40. I only have a 1000 miles, and hoped that it would resolve itself once the engine "breaks in." Hmm, I am going to have to research this issue. D#mned Flexfuel.
 

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Unfortunately, I have a FlexFuel 5.7 2013 CM and I'm getting 8.2-8.7 mpg around town also. I'd say that I drive conservatively also. A fair number of stop signs and an average running speed of 40. I only have a 1000 miles, and hoped that it would resolve itself once the engine "breaks in." Hmm, I am going to have to research this issue. D#mned Flexfuel.
I have the same truck you have and have been averaging close to 15 around town and 16-18 on the highway. Something isn't right there shouldn't be any reason why we all shouldn't at least 1-2 mpgs within each other.


Sent from AutoGuide.com Free App
 

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Run premium fuel and see if your mpg spikes up. I get better then 14 mpg in snow and 4x4 engaged. normal is 17 mpg, hwy at 60mph I'll hit 19s. freeways 70 plus 17s
 

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Discussion Starter · #16 ·
Dam that sucks man. I thought my mileage was bad. I get like 14mpg around town and like 18mpg highway. I drive like an old man though.

Once I get my supercharger and drop the truck (will go way down lol).

Good luck.
I drive like an old man too, I've pampered this truck. Metro bus takes off quicker than I do and the bus probably gets better mileage. Lol. Hope the re-flash works.
 
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Discussion Starter · #17 ·
See my thread(s) about FlexFuel and E85 sensor problems. Sounds like your rig is suffering from it, because low MPG is a dead giveaway, as well as other performance issues.

Good news is, just this weekend Toyota came up with a re-flash that should correct the problem. I was the first at my dealership to get it done. Here's hoping it works out.

.....and your dealer does sound like a tool.
Hey stompinstu. Do you know how the re flash is different from what they have done in the past to treat the problem with E85 misreadings?
 
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For you FFV guys that are suffering from low mileage, how does you tail pipe look? Is it sooty?
 
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Dealer kept insisting that it was my fault
I would tell the dealer to:
below
me

I'm considering pushing the lemon law.
That's most likely no longer an option (that or arbitration) as there is a TSB addressing the issue and a supposed fix now.

Hey stompinstu. Do you know how the re flash is different from what they have done in the past to treat the problem with E85 misreadings?
Who knows what they did, but it's a different firmware release by reading the actual TSB. So it's kind of like if your new phone sucks and you update it and it works now but looks the same, etc. Just some different coding.

For you FFV guys that are suffering from low mileage, how does you tail pipe look? Is it sooty?
Mine had a little black, but not too bad. I drove pretty hard once it was started and didn't do a lot of long highway stretches. Def. had a little soot that wouldn't simply wash off with a sponge at the car wash though.
 
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