Mph/Rpm ?

I just bought a 2012 toyota tacoma reg cab 4x4, automatic transmission, 2.7 liter, 46000 miles, 245/75r16 tires, 100% stock. I took it on the interstate for the first time and wow! It's running 2800 rpm's at 70mph, @ 75mph is was pushing 3400 rpm's. I thought maybe I'd go a little faster (83mph) to see if it would shift into another/higher gear, nope. I tried going down hill on the interstate to see if the rpm's would drop down or run lower, nope no different. Is this normal?

 

Yep.

MPH is related to RPM by the gear ratios in the drive train.

All vehicles are like this.

 

Those #'s seemed so far off, I just went out & ran my 2013 reg. cab, 4X4, 2.7, auto. down the rd. It had been a while since I was fooling with this & thought I may have forgot. You are way off, mine was like, 70 mph in D is appx. 2200, in 3 it's 3200, & in D then mash the gas enough to unlock the converter it jumps up to appx. 2500. All these little reg. cab 4X4's came with a 4.10 rear gear. Don't know what to say other than waaay different form mine

 

It sounds like you were in (3)rd and not overdrive (D). Mine will run around 2100-2200 at 70 mph in overdrive but I have bigger tires.

 

I believe that the automatic transmission 4 cylinder, 4 wheel drive regular cabs had 3.73 gear ratio. RPM seems very high.

 

I think this is correct. All the reg. cab 4X4 from maybe 2007 forward had the 2.7 eng & 4.10 gears, no other eng. or gear options were available for the reg. cabs. The auto. trans. was geared taller than the MT trans., enough so the ones with the auto. would have needed a 4.56 rear gear to be equal to the final ratio as the MT with the 4.10 rear gear.

 

IMO in all my years of driving the rpm's feels too high. I can't find anything regarding an overdrive. I did a search on my vin number to read all the specs, it doesn't say anything about an overdrive, nothing in the manual and no overdrive button on the gear shifter. It feels like it needs to shift one more time to drop the rpm's unless this is the way it's built and I'm just not used to it...?

 

My understanding also.

 

With your 340F trans., "3" is direct dr. 1.0 to 1.0, "D" is overdrive 0.7 to 1.0. In years past most all trans. Hi gear was 1.0 to 1.0 & anything with overdrive was marked so you would know it was an overdrive ("O/D", or a little square or circle with the "D" inside of it). Today most all trans. "are" overdrive so I guess they just figured there was no need to indicate it any more. Have you counted how many times your trans. shifts??? You should feel it shift, or see the tach. drop 4 times if all is shifting correctly.

 

Lets assume it's not shifting into 4th gear. Any thoughts on what might be causing that? With only 46000 miles I'm really hoping I don't need a new transmission.

Thank you everyone for you help

 

You know what "assume" is.....

It could be a simple fluid problem or a stuck valve or program shift point or a stuck solenoid........

Doubtful if a new tranny is needed.

I'd take to a transmission shop or Toyota for a diagnosis and quote of any repairs.

 

Do you have any CEL or ABS lights on? Overdrive won't engage until the trans fluid temp is up to a certain point. It sounds like there are several things that could stop it from going into OD. Do you have any type of scanner to look for codes or watch the trans fluid temp while driving?

 

There are no lights on at all, I don't have a scanner but I can definitely go buy one. How do you check for the transmission fluid temperature? I'm starting to wonder if this vehicle has been re-geared.

 

If you get something like an UltraGauge or Scangauge II you can add a pid to read the trans temp. Are you definitely putting the shifter in the (D) position and not (3)? My truck will shift into overdrive around 35 mph with it in (D). If your truck had 4-6" of lift then there might be a chance someone ran bigger tires and changed the gearing, but I doubt the gearing was changed on a stock truck. You might be better off going to a mechanic or dealer to check it out. It might be low on trans fluid or need a flush.

 

I checked the transmission fluid, it's good. From what I can tell its a stock truck, no lift, it has stock size tires on it 245/75r16. That was my thought too; why would someone re-gear a stock truck? Unless they were intending to lift it and never got around to it, idk. This a picture of my gear shifter and I don't see an overdrive anywhere.

 

I just punched your Taco in to "West Coast Differentials" rear Gear calculator. Punched in auto trans w/ OD, Your tires, appx. 31", 70 mph, & orig 4.10 gear should run 2177 rpm.... auto. trans. W/OD, 31" tire, 70 mph., with 5.29 gear should be running 2810 rpm. Also while looking at their catalog, there are 6 rear gears for the 4 cyl Tacoma 4X4's start with the tallest, 3.90 & the lowest is a 5.71. I'm just wondering, what's the chances either the speedometer or tachometer may be out of wack. It would be way, way odd for a orig looking Taco like yours to have a gear change. Way too expensive when you need to change both ends.

 

Yep, just like my 2013 shifter. the "D" is your OD, mine isn't marked OD either.

 

Did you count how many times it shifts, when taking off from a dead stop. If it only shifts 3 times, either it isn't shifting into "D" (4th) or the torque converter isn't locking

 

Did you buy it used? Maybe the previous owner installed 4.88 gears?

 

Yes I bought it used. That's what I'm starting to wonder, 4:88 or maybe a 4:56. I'm trying to search for a gear chart for the 2.7 liter engine but I'm not having any luck.