Hard shifting after premium gas

Okay, I have a 2012 prerunner trd off road with 31,000 miles with a fresh oil change and air filter but has not yet had its spark plugs changed.

I've noticed a very faint rough idle at lights that will occasionally "lurch" or bump/jerk lightly forward at lights. It's had a slightly hard shift from first to second gear that is pronounced and much harder than the very smooth and seamless shifting in the higher gears past 50mph.

The last few days as it's been getting warmer I've noticed the shifting to be growing harder from first to second and additionally a hard shift from park into reverse and reverse into drive. Today it almost resembled a deep pop.

This morning I had just checked the mpg at the pump and decided to see if I could find an improvement in mileage with shell premium 93 gas. it was this afternoon the shifting appeared to get harder.

I've searched and searched and read a lot on here but still feel the need to directly ask based on what I've read people say in the forums about

a.) The issue of 2010-15 trucks coming out of the factory 1-3 quarts short on transmission fluid, and noticing shifting problems with no way to check the level due to the sealed unit.

B.) the understanding that the newer trucks learn your driving habits and will adjust accordingly.

Is it possible the timing is off with the higher octane causing this? How prevalent is the low trans fluid issue.

I'm fairly certain the guy who owned it before me pulled a lot of trailers which concerns me.

I spoke with Toyota and as expected they gave me the lifetime fluid spiel and sealed unit spiel telling me the computer may need to be updated and that they just won't check the trans fluid level or even flush and change it if I wanted to.

The previous owners were on top of their Toyota maintenance schedule according to carfax so I would assume if the ECU needed updating they would have done it already.

Does anybody have any thoughts on this? Could it be spark plug related?

The vehicle also has a short, slight vibration around 20 mph when I floor it.

I'd like to get it in as soon as possible for diagnostic.

 

These dont need premium gas and in fact it hurts performance. Higher octane delays ignition so high compression engines dont get pre-ignition. Since our engines are not high compression the premium gas is delaying ignition and throwing the timing off. Never use premium fuel in this truck. It may not be the hard shift cause but it certainly isnt helping it.

 

There is no relation between your shifting issues and premium gas. It's like you got a flat tire because you put ketchup on your steak.

 

I wouldn't take a bicycle to aamco, they are the worst place to go.

 

Double A M C Whoa!

 

It does not hurt performance. The FJ and 4 Runner with the 1GR engine recommend premium gas as well. It does not throw off the timing either, there are high and low octane timing tables, controlled by a knock retardation system, this way it works with multiple fuels. Higher octane prevents pre-ignition, so more timing advance can be commanded by the PCM. If you have a scanguage/Ultragauge or some other data logger, you can view timing advance and knock retard.

 

Replace the plugs. See if that helps. Also maybe take the truck in and have them read any precodes in the computer.

These trucks consistently have rough shift problems as well as fuel injector issues leading to rough idles and hard starts.

Transfluid is NOT lifetime EVER. And NO ONE should EVER say that when it comes to a TRUCK. Hauling and towing habits as well as wheeling heavily determine how often one should change/flush/check the transfluid.

If you know a lot of towing has been done with it I would do a trans flush at 50-60k. Just me.

Also make Toyota check the transfluid level.

 

lol

 

Clean your mass airflow sensor,clean your throttle body,install new plugs

 

They do that lurch sometimes, keep your foot on the brake. My 07 was horrible about it, however my 13 doesn't do it as much.
If you think it's your transmission you can check the fluid level yourself there are write-ups on here.
But one thing is for sure it's not the gas octane .

 

Premium Gasoline will not hurt your truck! Toyota used 91 octane for their research numbers which is premium unleaded gasoline. In the online Toyota Tacoma Owners Manual, the selected octane rating is 87 or higher - lower gasoline with an octane rating lower than 87 may result in engine knocking and possible engine damage.

http://www.ttguide.net/fuel_information-159.html

 

Pretty much 75% of this post isn't true. Premium doesn't hurt performance, nor does it throw off timing.

 

Octane History 101

 

There is no fuel type to transmission co-relation. There is also no benefit in running a higher octane that called for. It just lightens your wallet.

I'd find a good independent shop that is familiar with the procedure to check fluid levels, and start there.

You are to be complimented for a well written post expressing both your concerns and what has / has not been done so far.

Let's see if @gearcruncher might have some helpful info on your described symptoms.

 

i stand by my post.

 

is the dipstick capped? could just be low on trans fluid...My Nissan was also capped but if you break the seal that held it on there was a dipstick you pulled out...IIRC...

 

There isn't a dipstick for the transmission at all on the 4.0

 

I'm guessing you recently started running the AC?

 

I appreciate the advice. I'm a bit of a novice to flushing the trans fluid, hopefully will have a some new plugs this weekend, that I can handle.
I'll search the forums for how tos on cleaning he MAF sensor, throttle body

I just couldn't find anything definitive on here about the hard 1st to 2nd shift issues, I would like to catch it early if it just needs fluid, once I read a post about fluid being low from factory I decided to start asking my own questions.

I also wanted to be as thorough as possible with what I had hanged in the last three days.

Guess it's a bad time to say that I tried lowering the tailgate and removing the secondary air filter for better mpgs? Lol
I'm just kidding.

I can't wait to shake these new purchase jitters.

Will be headed to the coast in two weeks hopefully that will help break her in for me mentally. But I'd like to have everything in top shape before I take the 3.5 hours hour drive.

Anybody on here in the Austin area that can recommend some good trusted shops?

 

https://www.tacomaworld.com/threads/diy-full-flush-for-automatic-transmission.68462/
OR
https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/
AND
https://www.tacomaworld.com/threads/how-to-throttle-body-cleaning-2005-v6.94203/