How do I increase towing performance?

https://www.tacomaworld.com/threads/obd-fusion-dashboard-swappin-thread.683932/#post-24114304

https://www.tacomaworld.com/threads/obd-fusion-tips-and-tricks.590248/#post-19721176

TBH I drive in S5 without ECT whilst towing most of the time and selecting lower gears if necessary. With ECT on at 63mph the trans wants to be in 4th, without ECT the trans will stay in 5th. I consistently get 12+mpg on long trips including mountain passes. I use ECT for engine braking down hill only.

Tacoma user manual does recommend ECT when towing but only mentions being outside of D when you need engine braking.

Well worth pinning your transmission thermostat open for towing trips. TBH whilst I’ve been in AZ this summer I’ve left it pinned.

https://m.youtube.com/watch?v=KB3Xbx97Emw

Torque converter lockup - it only locks in 4th, 5th & 6th gears.
Easiest way to think of it is when the torque converter is locked up the transmission does not heat up. If you’re climbing a hill and the TC is not locked the oil will heat up rapidly. In simple terms the TC locks up when there is not too much pressure on the gas pedal. On my OBD dashboard the red circle turns green when the TC is locked.

For me acceptable temps coming out of the TC are a max of 230’f and pan oil temps should stay under 200’f. Monitoring the TC lock up status is key to keeping oil cool. In 8k miles of towing a 5k trailer over most of the mountain ranges west of Kansas I’ve only seen pan temps go over 200’ once. That was climbing south of LasVegas into a headwind along Hwy 95.

 

Torque converter lockup is a GOOD thing.

Very high level conceptual over generalization here... But this is how it works.
Your Torque Converter is just a hydraulic pump. It takes engine power in the form of RPM to spin a pump that pushes fluid. That fluid drives the gears that powers your truck. So when you are going slower, lower gears, there is no mechanical link between tires and engine. It is separated by a fluid at the transmission. Using the fluid as that link causes it to heat up because the fluid is doing a lot of work to propel the truck. BUT! When the RPM, HP and Torque get high enough, the torque converter locks up and allows a direct mechanical link to pass through it so your engine RPM goes directly to the gears and on to the wheels.

Unlocked is smooth and easy, comfortable driving. The fluid does the work that a clutch would do in a manual and absorbs the friction and wear and tear. But it is less efficient.
Locked is direct and efficient and lets power straight through once the engine has made it through the RPM range when there would be more friction.

So for towing you want to get the RPM up in that "tow range" to keep the trans locked up. Once it is locked up, the fluid just provides lubrication and cooling.
I tried to search the internet to find the stall speed or lock up speed of our torque converters and couldn't. So if someone else knows what engine speed we lock up at I'd be curios to know for my own application.

And again - this is leaving out a ton of nuance and technical detail. For conceptual purposes only.

 

There isn't a specific RPM range where it locks. I believe it has more to do with torque needs of the vehicle. In my second gen I can easily watch my Tach and tell that I'm locked in. It can lock up at very low RPM. If I press lightly on gas pedal and the rpm doesn't really change you know it's locked, you might even lug it a little (continue pressing pedal slowly further with no increase in RPM), once you press far enough on the pedal the truck will unlock, and the RPMs will noticeably increase. A light on that OBD thing would sure make it easier though. It took me a long time watching it to really learn and be able to feel if it's locked up without really thinking or looking.

Once it's locked, I'll often only slowly give it more gas to accelerate (also slowly) in hope of it not unlocking. Sometimes this would even mean letting off the gas as I was near cresting a hill, slowing quite a bit to keep it locked, then once over the hill, slowly roll on the throttle. I often drive in the truck lane nowadays. Towing at 55 to 65 I can often get 10.5 or so mpg. I can also pull at 85, and get 6.0mpg. Too expensive to do that nowadays. Not to mention having to stop every 100 miles for gas.

 

Yep, all to do with throttle pressure. I’m typically in flip flops and drive barefoot. 63mph, 5th gear & no ECT is my sweet spot. 8k miles averaged nearly 12mpg with a 5klb TT.
Having the TC locked improves mpg considerably.
Was talking with OTT and they can program the TC to lock up fully in 3rd gear. This is my biggest gripe with the Taco, no 3rd gear lock up.

 

Nice to have the lock up indicator. On my scanguage I use the increase in temp to know when it unlocks!

 

If you ever tried to stop a 5000 lb trailer going down a hill with a 4000 lb truck You will buy a heavier truck

 

I have a 2015 tacoma 4.0 automatic transmission pee runner I pull a winabago 2306bh dry weight around 5400 pounds my truck shows no struggle what's so ever I use 4th gear for towing. I use equilizer bars. And I getting 10 mpg I check every fill up.tacoma is all stock.

 

Supercharger and ott tuned for me. Gears would be better after towing cars for a while.

 

I haven't towed anything yet with mine, but it does seem to be ready.
I've added a leaf spring and about 300 pounds to the bed.
The OTT tune put the torque in the lower rpms, that was money well spent.