5th gear issues and pleasant surprises

Howdy y’all,

I am in the middle of my first long haul in the taco — from eastern Tennessee to western South Dakota for a temporary fish hatchery gig.

First of all, I am surprised with the MPG. I have a full topper on the back, a brush guard, and a FULL bed of clothes, camping/fishing/hunting gear, and general household items. I STILL managed just under 2.5 tanks from start to Sioux City, Iowa. I’m pretty satisfied with that efficiency (~20 mpg).

Secondly, I can cruise around 75 in 4th gear but if I try and speed up, the truck literally will not shift into 5th gear until I’m pushing 3500 RPMs. It also jerk shifts into 5th unless I really push the RPMs, then it’ll shift fine. Once I am in 5th, the taco CRUISES. Through Missouri, I hit 95 without even noticing it (2600 RPMs). No rattles, shakes, or noises. Does anyone know why I have to push it so hard to shift into 5th but have no issues while in 5th?

Thanks y’all

 

Don't know your mileage, tire size, or loaded weight.
At 75 in 4th doubt 20 mpg - more like 15-18 best. In 5th you could as rpms lower if you did not push it. Congrats if you did get 20mpg!
If using cruise in hilly areas with a load that shifting is normal or if trying to stay at 75 up hill.
I take it off cruise in such times and let it slow on the longer grades and it stays in 5th. Shifting is load/speed based.

 

How many miles on the odometer? I would start with some new trans fluid and see how it feels after.

 

I'd like to get that kind of milage. Generally between 15-18 depending on stop and go/ city driving or highway.

Have you checked the tranny fluid level. I've read that they were coming out of the factory low. Might not be an issue in the later years, still worth checking though.

Lube guard..... Don't forget the lube guard.

There are several threads on the procedure as the fluid level needs to be checked in a temperature range.

As for the cruise control, mine seems to be an iteration of Jekyll and Hyde. CC has no problem dropping 2-3 gears when going up a hill, when rolling on the throttle would work fine.