Weak sounding start up?

My 2014 Flex Fuel with 29k is doing this. On a cold start it spits and sputters so much you think it may not start. This morning it did it and when I released the key the starter kept turning over for several seconds. I kept switching it off and restarting to see if it would do the same thing over and on the 4th start it would not crank and run. It has been doing this for 2 months and never does it when the engine is warm or Temps are above 50. I have never ran anything but 89 real gas.

 

My 2014 (42k miles) has recently started doing this EXACT same thing (for about a month). On mild mornings (50'ish) it will briefly spit and sputter before firing up. On one cool, foggy morning last week (low 40's), the starter turned over for a good 4-5 seconds, before I shut it off and tried again. It did it again for a 2nd time, before finally firing up on the 3rd attempt. In the afternoons, when I come out from work, it fires up with no issues...so it definitely seems to be influenced by temperature/high humidity. Once it's running...it runs perfectly fine...Literally no other symptoms. The fuel economy is unchanged, idle is perfect, power/acceleration is unchanged, etc. Although mine is a flex-fuel engine, it has never had e-85 in it...unfortunately there's not an e85 pump within 80 miles of my house. I've not really dug into it yet...was hoping to find some clues on here.

 

So the weak start happened to me when i brought it in for the fuel pump recall. I had to bring it back to dealership, the fuel pump was loose which caused the weak starts and other issues.

 

Looks like I found the most likely cause.

https://www.tundras.com/threads/rough-cold-start-on-2015-5-7.17231/

Post #12 indicates that it's a known issue with a solution.
Now I'm trying to figure out how to measure my alcohol content. I can't get my Torque Pro app to measure it.

Update: Found it in the Torque App...Holy crap, I'm measuring 85.1% ethanol. Other than the 10% ethanol that's in all of the local 87-octane pumps, I've never put a drop of E in the truck If this is accurate, I think I found my rough-start issue.

 

Did anyone find out the issue? My truck is having the same shit..
my battery seems find and keeps rolling the starter but my truck starts off with very low rpms. It just doesn’t sound right and takes too long to start.

 

I would find out what the truck is reading for Alcohol density. These trucks have a sensor that seems to only correct one direction. Mine started terrible cold. I brought it to Toyota and my Alcohol density was at 60% when I was running standard 87 pump gas which should be 10 or less.

The dealer reset my density and the problem went away.

This will only be a problem on cold start because that is the only time that the truck is using the density sensor with open loop. If the engine is warm it does not seem to matter as much. Obviously the colder it is the worse the problem will be.

Here is the TSB. It is older but the problem and procedure still applies. https://static.nhtsa.gov/odi/tsbs/2014/MC-10134184-9999.pdf

 

My 2015 TRD is NOT a flex fuel, and I have been having the same issues, and it is driving me bonkers. I had the issues earlier in the year, and my starter went out... replaced it. Didn't have the issue, but it was also summer by that point. Slow start came back. I have checked down the list, including installing a much better battery, but still have this happen in the morning or after long periods of being parked during the day.

I have been avoiding taking it to the dealer, because they kept my truck for several days earlier and failed to diagnose the issue then. I am waaaaaay beyond the warranty, approaching 240k miles. Am I just facing a fuel pump replacement at this point? Truck starts perfectly after that initial start, have no idling or power issues otherwise.

Any thoughts before I head to the stealership?

 

I may be wrong but flex fuel or not, they still have to calculate for alcohol density. Mine started out as a stumble/low rpm at cold start and then to the occasional stall and eventually morphed into an extended crank.
From what I understand the alcohol density is stored in the long term memory and will not reset with a simple battery disconnect. That did not fix mine.