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2016 Toyota Highlander - runs rough in winter

My 2016 Toyota Highlander Limited engine runs rough during the winter months (NY). Vehicle now has 45,000 miles stil no changes and no luck with Toyota for a fix.

please advise.

Is the check-engine light on?

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no its not, i had a diagnostic test done and all was positive.

When do you notice it? Does it run ok while motor is cold? Runs rough all the time?

I purchased the car new on August 2016, i noticed it the following winter of 2017 and reported it to the dealer which states its ok.
It does not run ok when its cold out, its so bad you can feel the vibrations when holding the steering wheel. At one point the toyota dealer changed the motor mounts thinking that was the issue but it wasnt.
During the cold weather it runs rough all the time. if it warms up to like 60 degrees it goes away.
This is so frustrating.

Does your Highlander have an ECO mode to save gas? The ECO mode on my 2013 Equinox lowers the idle speed causing some engine vibration and roughness. If you have it, try turning it off. I no longer use it as it has little effect on mpg (~0.7 mpg) and the Equinox driveability is much improved.

Ed B.

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No, I don’t have that mode on my 2016 .
I even try using the middle grade gas 89
But still the same.

Kenneth Hill

Even a cheap scan tool will let you watch coolant sensor temps. But, a bad sensor should trip a cel. You could look at short and long term fuel trims but it has had issues from new.

Have you tried another dealer if one is reasonably close? If that doesn’t help, contacting Toyota as described in your owner’s manual is the next step.

The complication here is that I assume your warranty is over by now. You did report the problem under warranty, so in theory they should continue pursuing this unresolved issue under warranty, but they might try to claim otherwise for various reasons. It would have been better if you didn’t wait so long.

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The car is a bit young and with low miles to think of a vacuum leak related to age and rot of a vacuum line, etc.
I wonder if there is a vacuum leak somewhere that may have been inflicted accidentally during some type of service.

Vacuum leaks will generally show up more during cold weather than warm. A vacuum gauge might show something with a smoke test as a followup test. The severity of roughness depends upon the size of the leak.

When did dealer change motor mounts? In 2016? Maybe they really are worn now? Or they left some bolts out? It happens

Do you have ABS system? Or maybe you didn’t change the tires?

Of course it has an ABS system . How can the tires make an engine run poorly ?

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Purchased new, limited addition.
Problem started around 12,000.

Kenneth Hill