Slow to start 2016 Sequoia 5.7 (1 Viewer)

[hank14]

2016 Sequoia 5.7 Flex Fuel. I purchased used in May 2020 with 69,000 miles.

Runs great, but over the last month I have noticed it taking longer to start and hesitating or rough idle right after starting (for 5-10 seconds). Only appears to be happening when the engine is cold.

Currently has 76,000 miles.

I am running regular unleaded (87 octane in my area) which contains up to 10% ethanol. I have never run E85 in it but don't know if the previous owner did.

I read some info online about the flex fuel vehicles having some slow start/ rough idle problems. Apparently there is a fuel sensor that measures the ethanol content on startup, and sometimes after refueling it will erroneously read the ethanol content and cause problems with the computer.

I ran a diagnostic on it and it isn't tripping any codes. The check engine light is not on and has not come on.

It runs great once it gets through the initial startup.

There was a mention on the forums here with a caution to not buy a flex fuel 5.7, but no specific details about it.

Anyone had a similar issue w/ their 5.7? Flex Fuel or not?

 

[Franken470]

Were you able to ever diagnose this? I have a friend with a 17' Tundra exhibiting the same symptoms as above, It's a 17' model with 125K miles and just started doing it as the weather turned cooler.

 

[hank14]

I never did figure anything out. It hasn’t done it in a long time but recently did as the weather turned cold again. I’m planning on taking it to an independent shop soon and will ask them about it.

Is your friend’s Tundra a flex fuel engine?

 

[Franken470]

I don't think so, I'm leaning towards a basic tune up since he says it hasn't had anything done in 125K other than oil changes. It may also be a precursor of the SAIS going out but trying to figure out when that happens normally on the 5.7L.

 

[hank14]

Interesting- I didn't know about the SAIS issues. I found the kit offered by Hewitt Technologies. May have to consider that if it continues.

Mine has never thrown a code of check engine light (yet) though.

 

[Franken470]

Interesting- I didn't know about the SAIS issues. I found the kit offered by Hewitt Technologies. May have to consider that if it continues.

Mine has never thrown a code of check engine light (yet) though.

That’s what led me away from SAIS, was no codes. It seems it’s generally working and then it isn’t.

 

[Franken470]

I finally got to the truck today and despite no check engine lights there are active codes. Reading the 200 forum I’m seeing this in 12-15 Tundras but thought it was fixed via TSB and eve modules being updated to correct the fuel trims it was misreading.

Further down the rabbit hole I go.