Better performance towing with ECT off... is this normal?

Hi all,

I got a travel trailer this summer and have towed it 15,000km around my province. I have a 2016 TRD sport DCLB w/ towing package. The trailer is 3750lbs loaded.

I read many suggestions online to use ECT power and S4 while driving. I did this for my first few trips and noticed the transmission gets close to overheating pretty quickly if I'm climbing lots of hills for extended periods of time. I sometimes end up having to just go 40-50km/h just so the temps dont go over 240F
In subsequent trips I towed with ECT power off and used S5. Same load all around. I am able to tackle these hills and hold speed, without temps going over. I also get better gas mileage all around.

Is this normal? It kinda contradicts everything I read about how ECT pwr is the tow/haul mode for the truck but I get better performance by not using it. Any clarification would be great! Thanks

 

Just curious.... temperature aside, does the truck 'perform' better without ECT? ECT tends to hold gears longer, and *may?* slip the TC more than non-ECT which might be accounting for your temperature differences. Long pulls on long grades with an unlocked TC can run up the heat.

 

I believe using S4 kind of defeats the purpose of ECT. S4 holds you in 4th while ECT just holds you in gears longer so that you have more usable power, if I'm not mistaken.

 

My experience so far is that the ECT definitely keeps the gears from racing to the next gear up, too quickly, but if I’m in hilly areas, I’m usually manually shifting it between 4th and 5th. ECT has no impact on that in my opinion. ECT is also annoying in stop and go/slow traffic so I turn it off. I need to get a scan gauge and see how my temps are when manually shifting.

 

S4 only limits your top gear to 4. It’ll shift 1-4 like normal.

 

It has better mpg and I can hold faster speeds while climbing hills. When on flat it will also shift to S5 which saves fuel as well. I didn't really notice any weird gear hunting with our without ECT.

 

I also found towing with ECT off yields a better towing experience. With the transmission in S5 and ECT on, the transmission would stay in 4th gear even on long flat stretches with no head wind. With ECT off it stays in 5th gear unless a grade calls for a lower gear. It also gets about 3 mpg better fuel economy with ECT off.