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Low gas mileage; paranoid or justified?

16210 Views 99 Replies 42 Participants Last post by  wildbill23c
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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I always run mid grade to high grade gas. I made a trip on Friday to Seattle from Bellingham and back with an average of 14.4 mpg with only myself and my100 lb girlfriend in an otherwise empty truck with 92 octane fuel. Anyone interested in speaking out against Toyota? I'm calling them again on Monday if I get no resolution I'm going to contact an attorney to see about a class action suit.
im in let me know!:D
Merrick I am with you. I was getting pretty bad mpg as well but I read on a thread today that the gas had a lot to do. I was always looking for the cheapest gas and I never really thought about it but today after reading I went to a gas station I know that has recreational gas. Non ethanol and paid 4.42 per gallon. I had some gas in the tank already but i poured about 64 bucks and after driving and geting avg of 9 / 12 i was getting 13 / 17.3. put it to the test. I am also running a KN air filter with wheels.
I normally run mid grade or premium and only from chevron or shell. I stay away from the off brands as much as possible. And I have never ran ethanol, E85 in my tank. Damn flexfuel motor is the problem. After every tank my mileage range drops 15-25 miles, my computer doesn't reset back to zero like it should instead it just adds the percentage of ethanol to the existing reading. If I have filled my tank twice with gas containing, say 8% ethanol. That's now reading that I'm using gas that is 16% ethanol and so on and so forth until the level gets so high that the E85 program kicks in and tries to burn regular gas as its ethanol. Causing my performance, power, and mileage to tank. I can't get Toyota to listen to me.
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I normally run mid grade or premium and only from chevron or shell. I stay away from the off brands as much as possible. And I have never ran ethanol, E85 in my tank. Damn flexfuel motor is the problem. After every tank my mileage range drops 15-25 miles, my computer doesn't reset back to zero like it should instead it just adds the percentage of ethanol to the existing reading. If I have filled my tank twice with gas containing, say 8% ethanol. That's now reading that I'm using gas that is 16% ethanol and so on and so forth until the level gets so high that the E85 program kicks in and tries to burn regular gas as its ethanol. Causing my performance, power, and mileage to tank. I can't get Toyota to listen to me.
Yah, I'm still in the same boat. 7.2 mph city. Got all the way up over 10 mpg on a 120 mile highway trip. Last time i had it at the dealer the alcohol was reading 88%. I've never put E85 in it and run mid grade or better from Shell/BP. Clearly there is a problem with either the Alcohol Sensor or ECU. I guess I'll try again with the local dealer, but honestly they are clueless.

I love my truck, but this is completely unacceptable.
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Have the same truck (pyrite mica) but would like to see a few pics of the interior for shorts and grins. As to the guy with crappy gas mileage, try adding a K&N Air filter. Not the cold intake, just the factory shaped one. I also added a Flowmaster American Thunder CAT Back exhaust. Together it added 20 plus horses and added almost 2mpg.

The truck actually glides when I take my foot off the gas. With the factory exhaust it would immediately begin downshifting.

Mike in AZ
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I use pure-gas to find the nearest ethanol free gas. They have apps for Android and Apples as well.

Chris
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Wow, i would be very upset with the mileage some are getting. I have a 2011 flex 5.7 and get 17-18 mpg on my 40 mile round trip to work. Can even get around 20 mpg straight highway. I have never used anything but regular gas. I accelerate slower than most and drive 60 instead of 65. I see many drivers floor it at every green light and hit the brakes hard at every red light. If this is your style of driving, dont complain about MPG
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Wow, i would be very upset with the mileage some are getting. I have a 2011 flex 5.7 and get 17-18 mpg on my 40 mile round trip to work. Can even get around 20 mpg straight highway. I have never used anything but regular gas. I accelerate slower than most and drive 60 instead of 65. I see many drivers floor it at every green light and hit the brakes hard at every red light. If this is your style of driving, dont complain about MPG
agree same here with the RW..if I drive hard its 15mpg. Its a brick into the wind..try tailgating - I pick up 2-3 mpg doing that :D Pushing people out of the fast lane at 75 I can get 17 if I'm riding dirty.
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Wow, i would be very upset with the mileage some are getting. I have a 2011 flex 5.7 and get 17-18 mpg on my 40 mile round trip to work. Can even get around 20 mpg straight highway. I have never used anything but regular gas. I accelerate slower than most and drive 60 instead of 65. I see many drivers floor it at every green light and hit the brakes hard at every red light. If this is your style of driving, dont complain about MPG
Thanks for replying but if you read the majority of the post you would have seen that we are driving conservatively. I'm happy that you have not experienced any of the problems associated with the flex fuel programming but I think that we are intelligent enough to know that aggressive driving affects mileage, it's just not the case here.
Sorry, didnt mean to imply thats the only problem. The fact that i have never used flex fuel supports your theory. Too bad Toyota is not interested in admitting the problem exists.
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Sorry, didnt mean to imply thats the only problem. The fact that i have never used flex fuel supports your theory. Too bad Toyota is not interested in admitting the problem exists.
Sorry didn't mean to come off defensively. The sad thing is most of us with this issue never have used E85 either. Really frustrating for us and Toyota ignores the fact that the reflash just doesn't cure the entire program or that some might have other issues that prevent the reflash fixing the problem

Thank you for taking the time to be a part of this thread every input helps pinpoint the problem.
Yah, I'm still in the same boat. 7.2 mph city. Got all the way up over 10 mpg on a 120 mile highway trip. Last time i had it at the dealer the alcohol was reading 88%. I've never put E85 in it and run mid grade or better from Shell/BP. Clearly there is a problem with either the Alcohol Sensor or ECU. I guess I'll try again with the local dealer, but honestly they are clueless.

I love my truck, but this is completely unacceptable.

Sooooo, I had to take my truck in for regular service anyway and I thought I would waste some more time waltzing down this rabbit hole. I asked them to record the fuel trims and alcohol density readings. After much prodding they came back with the long term fuel trims (+0.5 left bank; +5.6 right bank) which are with in spec, but I can't imagine it is ideal to have such a large deviation between the two banks? However, they claim that they are unable to read the alcohol density reading, even after contacting the field rep. Of course this is baffling since they gave me the reading last time and I assume that means they were actually able to obtain the reading previously.

Can anyone provide instructions on how to obtain this alcohol density reading? My truck is on day three at the dealer and I would like to facilitate the process. This really is frustrating.

Thanks.
Ok, so I have always had this question.... I believe the Average MPG is messed up on the Tundra. It says I am getting 10mpg but this is my conclusion

When I reset my mpg I get a decent 14-16 city 17-18 highway. Cool right. But when I'm either sitting at a light or in a parking lot you notice it starts going down. The Average MPG is not only counting traveling miles it is also counting just sitting there. :dunno: that's my conclusion not sure though
If it's burning gas but not moving, average mpg will drop. mpg is miles divided by gallons; if it burns some fraction of a gallon but did not move, then the result is a lower number.

I always like watching my SG as I drive off from the station, and it says I'm getting 4mpg. It'll climb up to say 12, then drop to 10 at a stop, etc. It fluctuates less the more miles I gather on the tank. What's sad though is watching the instant mpg while driving up a hill.
Ok, so I have always had this question.... I believe the Average MPG is messed up on the Tundra. It says I am getting 10mpg but this is my conclusion

When I reset my mpg I get a decent 14-16 city 17-18 highway. Cool right. But when I'm either sitting at a light or in a parking lot you notice it starts going down. The Average MPG is not only counting traveling miles it is also counting just sitting there. :dunno: that's my conclusion not sure though

The average mileage goes down while stationary with a running engine because you are burning fuel. If you we're to fill up your tank, reset the mpg reading and then let it idle until you ran out of fuel, you would theoretically see a reading of 0.0 mpg because you burned fuel, but covered no distance. That is why city mileage is lower - from the inefficiencies of starting, stopping, waiting, etc.

I hand calculate my mpg in addition to consulting the dash read out.
Back to my question above:

Can anyone provide instructions on how to obtain this alcohol density reading?

Thanks
The average mileage goes down while stationary with a running engine because you are burning fuel. If you we're to fill up your tank, reset the mpg reading and then let it idle until you ran out of fuel, you would theoretically see a reading of 0.0 mpg because you burned fuel, but covered no distance. That is why city mileage is lower - from the inefficiencies of starting, stopping, waiting, etc.

I hand calculate my mpg in addition to consulting the dash read out.
Just seems like when I had my expedition the average mpg was more accurate.
It probably used some sort of rolling average, say mpg over the last hour or the last 10 miles, and perhaps it ignored when sitting--or at least didn't update the display until moving again.

While I have the SG monitoring, I go by the tank avg, as calculated when I fill up.
Look in my "garage" and see whats also getting 9 mpg... You should be getting 15mpg with a stock truck i would think.
After reading these posts and watching my mileage more closely i have found it will drop 2 MPG by driving more aggressivley. My truck came with Michelin tires. I think tires such as the BFG all terrain radials would get less MPG. I can get 17-18 MPG on my 40 mile round trip to work.
Once you run that junk fuel through your truck it will take several tanks of fuel for the computer to correct itself. I was running regular 10% ethanol and started having serious hesitation issues, it took 4 full tanks of premium fuel to get the fuel system back to normal. I think I'm pretty close to what I was getting when the truck was new. Around town I usually get about 15-17mpg. Out on the highway I'm getting in the low 20's again. Trying to burn that garbage ethanol screws with your truck's engine and computer system, it takes a while for it to recalculate and somewhat reprogram itself.
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