2021 Trd Pro start and stall, surging etc

It has 140k on it, a few days ago started and stalled, restarted and then went on the way, got to the corner at a stop sign and it stalled. Got it going and was fine, next day took it to a friends shop and they ran the code scanner, no codes, also forgot to mention no engine lights on. So said battery voltage at crank was a little low, thinking it might just be the battery going bad I replaced it. Was fine for the day and the next day. Today started rolled out of driveway and stalled, restarted and went on the way. It then started surging while driving, basically felt like when pushing the pedal it was still trying to die but rpms jumped up. Got it home. Now it started, let it idle, turned AC on and died. Restart with AC off and it starts and dies. Any thoughts? Alternator was supposedly fine the other day when he checked it on their scanner.

 

possibly a failing fuel pump

 

hopefully not on a 4yr old truck

 

Sounds like the alcohol density % is high and this makes the computer think something is wrong and makes the truck to stall or long crank. Is a common thing on Flex Fuel Tundras I never ever had put ethanol in my tank and I had to reset mine like 2 times (2017 TRD PRO Flex Fuel) and this solved the issue without spending a penny.


You will need a computer with Toyota Techstream software and a OBDII cable or probably your friend have one of those bidirectional scanner tool in his shop to do this, here is a helpful thread for this issue.


https://www.tundras.com/threads/res...-bidirectional-scan-tool.123799/#post-3171202


If using Toyota Techstream software follow this guide


Here's a more detailed explanation:

1. 1. Problem:
   The alcohol (ethanol) fuel percentage might be incorrectly displayed, leading to issues like long starting times or poor gas mileage, especially in flex-fuel Tundras.
2. 2. Solution:
   A diagnostic tool that supports Toyota's Techstream software or similar bidirectional capabilities is required.
3. 3. Procedure:
   • Connect the tool to the vehicle's diagnostic port.
   • Navigate to the system selection and choose the Engine and ECT (Engine Control Module).
   • Locate and run the "Fuel Density Learning Value Reset" or similar function.
   • Follow the tool's instructions to complete the reset.
4. 4. Post-reset:
   After the reset, the vehicle's system should relearn the correct alcohol content. Some users on Toyota Tundra forums say that it may take some driving to fully recalibrate.
5. 5. Troubleshooting:
   If the issue persists, it could indicate a deeper problem with the fuel system or sensors, and further diagnostics may be needed. Some users suggest checking fuses and relays, fuel rail connections, or running a few tanks of non-ethanol fuel to help the system relearn

If your friend is using a bidirectional scanner tool at his shop tell him to check this video

https://youtu.be/oNetQin_o7g?si=SQ5pk5igCWVqgkG1


I hope this info help you to fix the issue.