mystery problem

ok you tundra wizards I need help solving the mystery of what going on with my truck, so recently with the cold temps my truck has been acting like it doesn't want to start after its been sitting overnight, like its spitting and sputtering right at start up but once it gets cranked it runs fine, nothing weird no misfiring at all, flash forward this week I went to start it up and my check engine light was on and the traction control off warning was on, I took the battery cables off and reset the computer and the code didn't come back on for 2 days. then it came back on so I decided to get my codes read at the local parts store, the results were many misfiring cylinders, I know my plugs and coils are good just changed them a month ago no problems so I'm thinking maybe the cold temp has something to do with it maybe fuel related? it only gives me problems when being sat up overnight any help would be appreciated what you guys think?

 

Search alcohol density reset. Very common problem that is a computer issue.

Flex fuel truck?

 

Since you just changed plugs and coils, go back and check your work. Did you use factory stuff or aftermarket?
Tundras dont like some aftermarket components, like coils or MAF. And plugs can be knock offs, depending where you bought them. Either could be contributing to the issue.

Is your tundra FFV? If so, you may need to reset alcohol levels.

Lastly, age of battery? If any doubt about it, to a volts and load test. Battery going out will cause all sorts of odd things to happen when the trucks systems dont get the required steady volts.

 

all Toyota products straight from the dealer, maf has been checked and is clean, idk how to tell if mine is ffv i dont think it is? battery is fairly new and is in good working order idk what it could be besides the alcohol levels but i figured it would reset with the battery disconnect?

 

Look at the sticker under the hood or gas cap. Gas cap will say E85 and the sticker will have the engine code.

Alcohol density does not reset by unplugging the battery. You have to actively reset with an OBD connected device.

 

it is flex fuel...

 

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

^ this is the answer.

 

well i had the codes cleared at autozone, maybe it will work this time only thing i can think of is its not getting enough fuel to crank causing it to spit and spudder and misfire....

 

It’s getting too much fuel. The computer thinks you’re running e85 and it’s drowning. Even when it fires it will run really rich which will cause other issues. Look through that thread linked above and you’ll realize it’s a common issue with thankfully an easy remedy.

 

i see what your saying but i dont have 3 bucks to spend on a scan tool lol

 

Where are you at?
I think Carista works for a lot less than that.

 

carista???? i dont know what that is... im in fl

 

You might be able to find a forum member nearby with a scan tool or techstream willing to reset. Google carista - it’s a plug-in Bluetooth module that should allow you reset the alcohol density on the ecu. Looks like $44 on Amazon. Read the thread to confirm it works but I think it does.

 

If you don’t want to mess with buying anything - find a reputable independent shop - it’s about a 10 minute process max so it shouldn’t cost you more than their minimum labor charge. You just have to tell them what you’re asking them to do - relearn the alcohol density value. You’re supposed to add fuel and drive immediately after resetting the ECU.

 

10-4 ill look into it

 

I concur with @AZBoatHauler - alcohol density reset is the first thing I would do and is a common enough thing on flex fuel vehicles. As he mentioned, the engine is getting too much fuel; ethanol has a lower energy density than gasoline, so it takes more ethanol to produce the same energy as if it were running on gasoline. If the computer thinks you have more ethanol in your fuel than you actually do, it will dump extra fuel and run rich. At startup, you are running rich already, so it will be running extra rich. It also ignores O2 sensor readings until the truck starts to warm up so it won’t adjust for the rich fuel condition at startup, which explains the hard start/sputtering when cold.

It’s not a big deal - just have somebody reset it with the appropriate scan tool. It will be cheaper than dumping all that extra fuel in to the motor, and MUCH cheaper than washing a cylinder and the ensuing havoc…

 

is this something i will have to keep doing or does it just go away?

 

Not unheard of having the ethanol % creep back up and need reset again. There is some speculation failing O2 sensors are to blame for the miscalculation but the reset seems to work for a long time if not indefinitely.

 

well that sucks lol

 

In a perfect world, sure it sucks. In our reality - it’s a minor inconvenience compared to issues with other power trains.

 

ill agree to that love my tundra has its quirks every once in a while, like this, but i love it its been the most reliable truck ive ever owned i do love the fact that I'm not having it in the shop constantly

 

Your truck is a 2014? So in 11 years, just expect it to pop up again...

 

Alcohol density is your problem. Had it happen two or three times on my 2013 with Flex Fuel 5.7. Only happened in the winter time. Each time my local Toyota dealership reset it for free, because it was such a common issue. Thanks to this site, I told them what the problem was when I went in.

 

You have a good dealer.

I've heard of it happening much more in the winter, but especially so as of late. I'm told that refineries are now allowed to mix up to 15% ethanol instead of 10% max as has been the case for a decade or so. I'd have to dig up the info, so don't take it as a sure thing but I wonder if that is a contributing factor.

 

lol i guess thats not bad odds

 

so update im having my truck tuned tomorrow with the overland tailor tune and the tuner said he could reset it, hope the tune makes a big difference like everyone has said it does

 

OTT does a great job. You’ll love the truck even more.

 

is yours tuned? @blenton

 

Yup. My tundra has a whipple, my sequoia has an OTT naturally aspirated tune. Big improvement in driveability, makes a little more power in the power band, but still super smooth - like the factory tuner actually enjoyed driving the vehicle.

 

@blenton what option did you go with on the n/a? and what do you mean by makes a little more power in the power? im for the most part happy with the way it runs now just wish it had a little more pep, is that what your talking about?