Not Shifting Into 4th @ 40MPH

Everyday when I leave the office I have about a mile drive with 40mph speed limit. My truck stays in 3rd gear the whole way which is right at 2000 rpm. I didn't really notice it until I put on my Thrush Turbo Muffler and I'm guessing that's only because I can hear it now. Is this normal? It only seems to do it when the temps are cooler. My truck is a '15 is a DCSB with 4cyl auto.

 

I have an Ultragauge in mine ( 2012, 2.7 liter 4 cylinder automatic ) and I have noticed that it only shifts into fourth when the engine temps reach 130 degrees. There was another poster that was complaining about it and I monitored mine over the course of a week and this is consistent. No shift to 4th until it reaches 130 degrees.

 

From what I have understood from my old man, a lifelong mechanic specializing in automatic transmissions, is that RPMs have been tied to engine/transmissions temps for decades. It is normal to have a delay in upshift so that the engine/trans gets to operating temps faster.

 

this

 

And your old man knows what he is talking about.

 

yes delay in loading tranny when cold.

my yaris is really noticable and it actually has a special
light on the dash that won't go out till the tranny gets warm, and then it shifts to D

my 4runner with a340...from 1998 to 2011 I never noticed. when I had the thing
-=-completely rebuilt-=- in 2011 (milkshake got me, damn old radiator)
I noticed it, as it had updated tranny ecu as well as better temp sensors

 

Thanks guys. I thought it might have something to do with the temps. I appreciate the responses. Guess i need to do a burnout in the parking lot everyday before i leave to get the temp up! HAHA.