Flexfuel Engine--what should I know about it?

Hi all, what exactly is a flexfuel engine? I see that I can run higher ethanol % fuel and oil changes are required every 5K miles, but are there any other differences that I should know about with these engines? Are they as reliable as a non flex fuel? Any problems associated with them? Thanks!

 

https://www.caranddriver.com/research/a31542970/flex-fuel-benefits/

 

Let's just say if life isn't providing you enough interesting challenges...Say, like being laid off, wife had affair with your best friend and wants divorce, checking account is overdrawn and banks charging you overdraft fees, finding out your identity has been stolen and over-utilized by the best, learning that your unmarried teenage daughter is pregnant, hearing that your son has been arrested for dope dealing in Mexico, and learning you have terminal lung cancer...then, by all means, seek out a Tundra 5.7L flex fuel truck for the time you have left.

 

Yeah, I've overdramatized the problem. Only a few flex fuel Tundras have issues...But when they do, it's a Duesy.

They say "what doesn't kill you makes you stronger". I'm just sayin' I wouldn't intentionally go looking for a flex fuel Tundra to make myself stronger. I got enough problems, and I'm relatively problem-free.

 

Bigger injectors on the FFV 5.7.

Mine had a warranty fuel pump replacement and ECU update/reflash. Been problem free since.

Added a 46 g Transfer Flo tank when they warrantied the pump.

I run Chevron 91 fuel FWIW.

 

IMO, that's actually an acceptable maintenance history, especially that "problem free since" part.

If you can get the problem fixed with one reflash, that is an excellent outcome. One owner on another forum had to have his periodically reflashed, and that would make me very unhappy. If my Toyota has to be in the shop all the time for reflash, might as well have a Ford.

 

I have one. Zero issues. I don't, won't run FF.

 

I think only FF was available on the lot when I bought mine. I run 89 in it all the time, unless I can run 91 no ethanol then I will. No issues. Never has had e85, never will. Even a service tech asked me about it once and he said don't put it in unless you plan to continue using it. I honestly don't even know where I would go to get it around here, it's not very common.

I've followed the 5k maintenance, and I think I would even if I didn't have a FF engine. You'll be fine with one.

 

Another flex. One reflash and that’s it in 50,000. They are every bit as reliable as the non flex until someone on here proves me wrong. Other than a quick software update I have yet to hear people complaining about their reliability.

 

I have a 2017 with the 5.7L FFV but have never run anything other than regular 87 octane. Have not had any issues - what reflash did you get and why? Is there a TSB?

EDIT: Is T-SB-0166-19 the right one? Did you folks that had the re-flash done experience symptoms? If so, what were they - continuous or intermittant? My MPG sometimes goes lower than what I think it should. I have attributed it to winter gas. Might want to have the reflash done but I would likely need to say I've experienced the symptoms.

Buckaroo

 

Not sure if that’s the one but I had really rough starts due to the computer thinking I was running ethanol. I have and never will run it in my truck. After the reflash I haven’t had any issues.

 

Actually, I should have kept my peace, since I have no direct experience with Flex Fuel.

But, I have read other owners' misery for several years now, and I am surprised there are as many "happy 'flex fuel' campers" as there are on this site. There have been a few complaint threads here, but not like the other forum. This is not a new problem, even on Tundras.com (Search Flex Fuel Problems). The single reflash solution is relatively recent, as in the last couple of years. One thing I do know: They don't make Flex Fuel Tundras anymore. What does that tell you?

This thread from another forum pretty well sums up what CAN happen with Flex Fuel Tundras. Note the results of this poll taken in 2015: 61% never had a problem, 7.5% got the problem fixed, 32% never got the problem fixed.

Apparently, from today's discussion, the good news is that Toyota has finally figured out how to fix the problem...permanently:

https://www.tundratalk.net/threads/have-you-ever-had-an-ffv-problem.397473/#post-4947185

 

No issues here, 125k on the clock. The only issue with my truck is non-FFV related which is 2nd gear power loss at WOT, even with LSD, and nannies turned off. Going to do the trans solenoids after one more zero calibration.

 

I’ve owned both, no difference in ownership experience. Automakers are eliminating and reducing flex-fuel vehicles due to the EPA getting rid of incentives to produce them.

 

Flexfuel Engine--what should I know about it?

Two things must ye know aboot the FlexibleFuel engine.

The first thing is it requires fuel.

The second thing is you have a wide choice of approved fuels for the engine making it very flexible to refuel.

 

Ah but does it rub? And what is the impact on mpg’s and of course the transmission?

 

OP, buy either 5.7 engine with confidence. There are no major issues with FF. The boogie man won’t pop out when you go to refuel.

 

FFV here. I too have had ZERO issues. I change the engine oil............wait for it..............wait for it...........wait for it...............every 10,000 miles. Blackstone Labs gives glowing reports. The 5,000 mile interval that you read about in the Owner's manual is because Mama Toyota MUST assume a FFV owner is running E85. They must. If you don't run E85 then follow the non-FFV OCI. It really is that simple.

 

It heats up the transmission.

If only there was something to make it cool...





I'll see myself out lol

 

Agree with your point but I change it every 5,000 miles because I tow and work it pretty hard. When I had the Dealer changing it free under ToyotaCare, they also changed it every 5,000 miles because it was FFV which I really liked. I have a '17 Camry and change that every 10,000 miles. Back in the day before synthetics, I used to change the oil every 3,000 miles.

 

One potential downside to the FFV is the annoying refueling procedure. Like the manual says it's best to drive at least 5 miles after fueling (I do minimum 7 to be sure), and in those first 5 miles don't get on the highway and for the funky lovin of all things musical and good in the world do not ever under ANY circumstances go full throttle, especially after changing fuel type. There's no alcohol sensor and it has to read (guess) from what the air/fuel sensors are saying versus what fuel it thinks it's throwing at it, and there's the variable of the two speed fuel pump too. If you don't follow those rules the PCM will get the alcohol number wrong. Mild annoyance if you're running gas and it gets a false high alcohol number, so it runs super rich on open loop i.e. cold start (might not start...) or WOT. I think it defaults high on the estimated alcohol% when the relearn is messed up because if it was filled with E85 and mistakenly sets the fuel numbers low for gas, it would go lean at the first open loop WOT condition and bad things could happen. When running just normal gas I can always tell when I didn't drive far enough before shutting it off or broke the first 5 mile rule in some other way because that tank would have an automatic 2-3 mpg penalty.

With a non-FFV just put gas in it and drive.

As far as E85 usage goes it hasn't given me any problems yet. The stuff cleans carbon out of the motor like Seafoam and the extra low end torque is fun. The 26 gallon tank feels even smaller though and the oil has to get changed out a bit more often. Ford and GM recommend a tank of gas after 2-3 tanks of E85 so I make sure to switch... no more than 3 tanks of corn oil followed by at least 2-3 tanks of gas. My motor starts to ping at low rpm after long-term gas usage and this regimen keeps it purring smoothly.

 

I agree but for warranty purposes I’d suggest following their recommendation.

 

I don't think E85 vehicles will have any problems with regular fuel. I would never put it in any of my vehicles.
I sell gas station equipment (gas dispensers and tanks etc) if someone wants to put E85 tanks and dispensers in, all the equipment has to either be stainless steel or nickel plated aluminum. E85 will eat up aluminum or plain steel. The upcharge per dispenser is about 5K per unit, submersible pumps flex lines all have to be special. I'm sure the car manufacturers don't go through such lengths to protect the vehicle since they only have to last past the warranty.
Also, i'm told the mileage goes way down and doesn't cover the savings per gallon.
on the other hand, if you purchase a flex fuel truck and never put E85 in it, should last longer since some of the components have upgraded.

 

I've always hoped a hot boogiewoman would pop out when fueling to entertain me in the long wait to fill the big tank. Hasn't happened yet.

 

I've never had an FFV vehicle. So what are you supposed to do if you pull off the interstate to fuel up? Just go super easy on throttle to get to speed?

 

No, just don’t accelerate rapidly leaving gas station, only when switching fuels.

 

What he said.

Or just don't use the crap!

 

Same here.

 

Not sure where I got the 'stay off the highway' thing in my head. It's not in the older manuals either. Good to know. I looked in the service manual and the ethanol learning procedure in there is 2 minutes of idle followed by 5 minutes of driving, specifying a target speed range between 37-75 mph and no hard throttle. So that's not completely consistent with the owner's manual I guess.

It's the drive 7 miles thing that always torches my tootsie. My favorite gas station is two miles away so I get to find a much longer way home. If I drive straight home and shut if off then goodbye mpg for the whole entire tank.