Threshold to use tow haul mode?

[cheesedogf150]

Looking for feedback on when to engage tow haul mode.

Anytime I’m towing I have it engaged. How about when hauling stuff in the bed. Do you engage it when you hit a percent of max payload, when you hit a round number on weight, truck drive feel?

Curious what the best practice is for enabling it for hauling. Thanks.

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[HammaMan]

I don't use it unless I'm towing a larger box trailer any meaningful distance. The truck just isn't working hard enough to warrant it otherwise.

 

[turbopilot]

I don't use it unless I'm towing a larger box trailer any meaningful distance. The truck just isn't working hard enough to warrant it otherwise.

I have found with flat terrain, no wind or tailwind, my PB seems to do very well towing a 7,100 Airstream trailer in Normal Mode with a slight increase in milage. With head winds and/or mountainous terrain, I go to Tow/Haul mode. Make sense?

 

[JExpedition07]

Anytime you are towing a trailer is the correct answer, the purpose of tow/haul mode is to protect the torque converter and transmission clutches. It keeps the torque converter from locking up in every consecutive gear like it does in normal mode, which would create a lot of extra heat in the transmission if it’s locking up all the time with a trailer behind it. It wears on your torque converter lockup and OD clutches faster if you are not using it.

Before tow mode (like my 2007 Expedition), you generally locked out your overdrive gears if towing.

 

[turbopilot]

Anytime you are towing a trailer is the correct answer, the purpose of tow/haul mode is to protect the torque converter and transmission clutches. It keeps the torque converter from locking up in every consecutive gear like it does in normal mode, which would create a lot of extra heat in the transmission if it’s locking up all the time with a trailer behind it. It wears on your torque converter lockup and OD clutches faster if you are not using it.

Before tow mode (like my 2007 Expedition), you generally locked out your overdrive gears if towing.

That sounds reasonable but watching the real time temperatures in both modes I have not seen any meaningful differences. Transmission temps seem to stay in a very narrow band of 210F to 220F with any outside temperature towing my Airstream. Here is a screen shot at 95F outside air temperature crossing the divide near Grants, NM.

 

[Nasto]

I have found with flat terrain, no wind or tailwind, my PB seems to do very well towing a 7,100 Airstream trailer in Normal Mode with a slight increase in milage. With head winds and/or mountainous terrain, I go to Tow/Haul mode. Make sense?

What’s your truck’s max payload according to your door sticker and do you get close to that when you’re towing your Airstream?

 

[turbopilot]

What’s your truck’s max payload according to your door sticker and do you get close to that when you’re towing your Airstream?

I have a loaded Platinum. With 840 lbs on the hitch I am very close to the maximum payload for the truck towing the Airstream.

 

[HammaMan]

I have found with flat terrain, no wind or tailwind, my PB seems to do very well towing a 7,100 Airstream trailer in Normal Mode with a slight increase in milage. With head winds and/or mountainous terrain, I go to Tow/Haul mode. Make sense?

The only thing to keep in mind is that oil flow to the turbos ends when the ICE turns off. If you just had a big climb and then pull off to a rest area or something you're not cooling the turbos or keeping cooler oil flowing through them while temps come back down. Since there's no temp probe on them there's really no way to gauge their temp. That's something you'd know. Might be wise before going to park to arrive w/ tow haul for the last couple minutes of the drive.

 

[turbopilot]

The only thing to keep in mind is that oil flow to the turbos ends when the ICE turns off. If you just had a big climb and then pull off to a rest area or something you're not cooling the turbos or keeping cooler oil flowing through them while temps come back down. Since there's no temp probe on them there's really no way to gauge their temp. That's something you'd know. Might be wise before going to park to arrive w/ tow haul for the last couple minutes of the drive.

Interesting point, that should also be an issue when not pulling the trailer. If there is no oil flow every time the ICE turns off with hot turbos. In turbocharged airplanes I always allow about 3 minutes of idle cool down for the turbos before shutting down to prevent coking.

 

[HammaMan]

Interesting point, that should also be an issue when not pulling the trailer. If there is no oil flow every time the ICE turns off with hot turbos. In turbocharged airplanes I always allow about 3 minutes of idle cool down for the turbos before shutting down to prevent coking.

It is but that's the design threshold for the engine. Towing's increased power requirements can skew that. Not sure where the threshold is since turbo temp really doesn't correlate to other temps when the cooling system is keeping up. Not sure of the efficacy in mitigation from the turbo's water cooling. One thing I'd like to see w/ the PBs is a little aux oil and water pump to keep cooling and oil flowing to them. The AC keeps the fan running when warranted so a set of aux pumps would be quite nice.

 

[turbopilot]

It is but that's the design threshold for the engine. Towing's increased power requirements can skew that. Not sure where the threshold is since turbo temp really doesn't correlate to other temps when the cooling system is keeping up. Not sure of the efficacy in mitigation from the turbo's water cooling. One thing I'd like to see w/ the PBs is a little aux oil and water pump to keep cooling and oil flowing to them. The AC keeps the fan running when warranted so a set of aux pumps would be quite nice.

In turbocharged airplanes we have turbine inlet temperatures (TIT) for each turbo. Pretty good proxy for turbo bearing temperatures, typically in the range of 1500 to 1600 F. During the 3 minute turbo cool down at idle you can watch those temps tail off. Pull the mixture abruptly just after landing you can often see the TIT's go up sometimes before cooling down.

Do we know for sure oil flow stops to the turbos in the PB ICE during routine engine cycling?

 

[HammaMan]

@Snakebitten likes to go into the specifics of the various loops, perhaps he knows if there's any aux coolant pumps. There's one in the trans, haven't seen anything for engine's cooling side of things. The PB's batt / DCDC / motor inverter have their own low pressure coolant loop.

My mach-e has 4 coolant pumps on, all electric of course.

 

[Snakebitten]

The only electric engine coolant pump that I know of is in the HVAC loop.
And as you mentioned, the electric auxiliary pump in the transmission for shift line pressure on the clutches during ICE off events.
There is an electric pump for the Hybrid electric coolant loop, but I'm not sure where it is.

I don't know of any electric pump for engine oil, nor one for engine coolant.

 

[Snakebitten]

Engine Coolant Loop

 

[FordFan2022]

That sounds reasonable but watching the real time temperatures in both modes I have not seen any meaningful differences. Transmission temps seem to stay in a very narrow band of 210F to 220F with any outside temperature towing my Airstream. Here is a screen shot at 95F outside air temperature crossing the divide near Grants, NM.

What app are you using here? I dont have a PB but a 5.0 stx and have tried and tried to see my trans temp using torque and obd fusion. I cannot find a pid formula to add the temp myself.

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