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Flex fuel alcohol sensor?

22K views 26 replies 11 participants last post by  Mikecol 
#1 ·
I have a 2015 pro FF SC(85,000 miles) it’s ran fine for 60,000 miles supercharged with the unichip.
The last 15,000 miles the alcohol sensor has been reading high and it’s sometimes is hard to start when it’s cooler outside and busts up at wot. Is there anyway to clear the alcohol % so it will run ok?
 
#2 ·
I spoke with a friend who is a mechanic for Toyota who said there is a update for the ecm just for this and it’s free. They actually update it and drain 4 gallons of gas and add it back to make sure the computer is reading it after the reset.
I’ll let y’all know if this works. Should have it in by next week.
 
#3 ·
See if you can get the update number, or TSB, as I have searched, but not found the update. Might be different for my 17.
 
#5 · (Edited)
There isn't an alcohol sensor on the Tundra FFVs. The system calculates the alcohol percentage based on an algorithm and how the truck runs/reacts on the fuel via O2 sensors and etc.

The last update I remember mentioned was in the 14 model year. I don't think I've heard of a 15 plus being affected. My 14 FFV hasn't had any issues thank the Lord.

By the way.... how you liking the SC and the UNI?

You can reset the value with tech stream but I personally its hard for me to trust the hacked versions out there.
 
#8 ·
My 2010 didn't have any issues at all. Read 7% with the fuel I was and still am using. It would fluctuate, but never outside of the norm.

My 17... Would read funny, high, creep up to mid/upper 20's. They reset it and all was good, then it locked itself at 0%.

Dealership said in July a update was coming out, just haven't heard anything. I inquired, but never got an answer back. Still have to go in for my last oil change, and hopefully they figure it out. Should be going in next week. Waiting to Dap my truck till it goes in.
 
#6 ·
Thanks for the info. I’ve had good luck with the unichip so far. The wot shift hesitation is still there but other than that it’s ok. I would like to get a better tune if there is one that actually works on a FF.
I’ll post everything that Toyota does and was told it’s free so we will see.
 
#7 ·
Thanks for the info. I’ve had good luck with the unichip so far. The wot shift hesitation is still there but other than that it’s ok. I would like to get a better tune if there is one that actually works on a FF.
I have a question about resetting with the tech stream. Will the truck run ok after you reset it for awhile?
I’ll post everything that Toyota does and was told it’s free so we will see.
 
#9 ·
I am beginning to think it’s how it’s driven after you fuel up. Call me crazy, but my truck had been locked at 20% for a while, and I think it had to do with that I filled up the tank at the gas station that was 0.5 miles from my house and not giving the truck time to go thru it’s calculation. I’ve started filling at a station that is 5+ miles from home. Also to note...the manual calls for an FFV truck to be driven 7 miles or 5 min after fueling.:.im pretty sure now both need to happen instead of one or the other. My truck now consistently reads 11%- which is correct as I use e10- when it was pretty much locked at 20%for a year.
Maybe that is the case. I don't drive much. 14k on my 2017, that will be two years and one month old on the 19th of this month. Fuel station I use is 4.5 miles from my house. Often I fill up, then hit the grocery store, which is only half mile away. Then I head home, which that route is only 4 miles.

I have not monitored it since it locked at zero. I checked it several times, over several months, and it was always at zero, so I stopped reading it as I had read here that once it locks to zero, it needs a reset.

I normally only need fuel every 2-3 weeks.

However, my 2010 I did the same thing with, same fueling station, same grocery store, and it never had an issue, even though it was in the problematic year range.
 
#10 ·
I had a problem with the alcohol sensor on my '15, rough start and it blew black smoke on start up. The day I took it in for service I got the check engine and traction control lights come on, thank goodness it didn't go into limp mode. Toyota flashed the ECM and I haven't had a problem since but I've heard you can disconnect the battery for 15 minutes or so to let it reset but this sounds like a temp fix so I'd take it in and get it fixed.

My thoughts it's got to have some kind of sensor to detect the gas to alcohol mix.
 
#15 ·
I had the issue not too long ago as well in '15. Took it to the dealership and the ecm was reading alcohol density at like 76% or something crazy like that. Had really rough cold starts but would on do it in cold weather. I think it also affected fuel mileage as well

For the record here is the TSB if anyone else has the issue. I actually had one dealership tell me you couldn't read the alcohol content and I knew they were stupid and I won't be going there anymore. Took it to another dealership and showed them the TSB and truck has been running much better since.

TSB: http://www.revbase.com/BBBMotor/TSb/DownloadPdf?id=187888
 
#23 ·
Still running the unichip, it’s running better now because of the update.
The dealship I was using for oil changes never checked for any updates even though I asked.
They wanted to blame the unichip and it being a ff supercharged engine.
I took it to another dealership where I know the head mechanic and he took it from there.
 
#26 · (Edited)
As far as I know, the system calculates the percentage of alcohol content based on an algorithm and how the truck is moving/responding to fuel using the O2 sensors. I don't think there is an alcohol sensor on the Tundra FFV. But I could be wrong. Try resetting the value with tech stream, but I personally have a hard time trusting the hacked versions. If not, try Abbeycare Scotland. I had a problem with the alcohol sensor on my '15, a rough start, and it blew black smoke at startup. Toyota flashed the ECM, and I haven't had a problem since. Still, I've heard you can disconnect the battery for 15 minutes or so to let it reset, but that sounds like a temporary fix, so I'll take it and fix it.
 
#27 ·
I had my fuel pump changed and ECM reflashed to fix the % alcohol issue in my 15 CM 5.7L FFV (hard start, reading 82% alcohol). It runs fine now. Since that repair (about 2000 miles ago), my % alcohol reads 0%. I am running E10. Will it ever read 10% alcohol? Is it OK to read 0%? I am thinking if it reads 0% when I am actually running E10% that I would be running a little lean.
 
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