Any danger in forcing downshifts? Or lugging engine?

[LG_123]

We're partway through a 5 week road trip towing a 7,000lb travel trailer and I've noticed that when going uphill the Expedition is very reluctant to downshift, especially from 7 to 6 (I normally drive in 7-8 when towing around 60 mph). It's a 2019 Platinum with HD tow and lots of practice towing.

This continues even under 1800 RPM. Isn't it a bad idea to lug the engine like that when towing a heavy load uphill?

So I've been using the buttons to delete gears and force a downshift to keep the RPMs above 2,000.

Is it a bad idea to force a downshift like that when the car doesn't want to do it on its own? And is there any risk of damage to the engine if I let it chug along down to 1500 RPM before downshifting, other than losing speed and not being able to easily accelerate?

 

[BravoAlpha]

So I've been using the buttons to delete gears and force a downshift to keep the RPMs above 2,000.

in Trailer mode- that’s what I would do.

 

[Zig10]

Do you have the transmission in tow mode? I just pulled my boat (7500 lbs) a little over 500 miles and it reacted pretty well when I needed to get around slower traffic. It does shift less in tow mode to keep the transmission temps cooler. If you put it on gauge mode you'll likely see that it'll add most boost from the turbos before it'll downshift.

I don't think you'll hurt anything manually shifting if you choose.

 

[GlennSullivan]

The 3.5 Twin Turbo engine will use less boost in lower gears when towing uphill. With my 2017 / 6 speed towing either 6500 or 4900 lbs, I manually control the gears when going uphill or use Tow / Haul mode. Tow / Haul mode on my truck works well uphill, but I don't like the way it is programmed for downhill where it drops gears in an attempt to slow the vehicle, causing the engine rev high. I think causes more harm than good, If I need additional braking on a steep downhill, I just use the manual control on the TBC. I'd rather replace a set of truck or trailer brakes than an engine - after all its not a diesel with a Jake Brake designed for engine braking.

I also assume you are using 93 octane when towing, if not, you should be, you will get better mileage and the engine will not work as hard.

 

[LG_123]

The 3.5 Twin Turbo engine will use less boost in lower gears when towing uphill. With my 2017 / 6 speed towing either 6500 or 4900 lbs, I manually control the gears when going uphill or use Tow / Haul mode. Tow / Haul mode on my truck works well uphill, but I don't like the way it is programmed for downhill where it drops gears in an attempt to slow the vehicle, causing the engine rev high. I think causes more harm than good, If I need additional braking on a steep downhill, I just use the manual control on the TBC. I'd rather replace a set of truck or trailer brakes than an engine - after all its not a diesel with a Jake Brake designed for engine braking.

I also assume you are using 93 octane when towing, if not, you should be, you will get better mileage and the engine will not work as hard.

Our engine does rev pretty high when descending sometimes; I hope it doesn't cause any issues since there's not much I can do about it on some of the 12% slopes with a heavy trailer pushing us.

We're running 91 octane. There's nothing higher anywhere in the Canadian maritimes and in Newfoundland some of the premium is real garbage; it must sit for long periods so we burn a lot of it and some oil if we can't find a busy station to fill up at.

 

[JasonH]

We're partway through a 5 week road trip towing a 7,000lb travel trailer and I've noticed that when going uphill the Expedition is very reluctant to downshift, especially from 7 to 6 (I normally drive in 7-8 when towing around 60 mph). It's a 2019 Platinum with HD tow and lots of practice towing.

This continues even under 1800 RPM. Isn't it a bad idea to lug the engine like that when towing a heavy load uphill?

So I've been using the buttons to delete gears and force a downshift to keep the RPMs above 2,000.

Is it a bad idea to force a downshift like that when the car doesn't want to do it on its own? And is there any risk of damage to the engine if I let it chug along down to 1500 RPM before downshifting, other than losing speed and not being able to easily accelerate?

Running in a lower gear will reduce boost and reduce heat build up by reducing load on the engine and running the water pump harder. It's ok to use the lower gears when needed to maintain RPM. The Ecoboost likes to be in a higher gear, likely for MPG. But that's isn't necessarily the best option when towing and you might actually see better mpg in a lower gear.

 

[LG_123]

Running in a lower gear will reduce boost and reduce heat build up by reducing load on the engine and running the water pump harder. It's ok to use the lower gears when needed to maintain RPM. The Ecoboost likes to be in a higher gear, likely for MPG. But that's isn't necessarily the best option when towing and you might actually see better mpg in a lower gear.

Interesting, I didn't realize it would reduce heat buildup to stay in a lower gear. I thought it should be the opposite since it feels like there's more strain on the engine when it's under pressure in a high gear instead of opening up in a lower gear. Thanks for the info.

 

[JasonH]

Interesting, I didn't realize it would reduce heat buildup to stay in a lower gear. I thought it should be the opposite since it feels like there's more strain on the engine when it's under pressure in a high gear instead of opening up in a lower gear. Thanks for the info.

If you're not already doing so, consider running a ELM327 Bluetooth OBD adapter and Torque app while towing. It gives great info on engine operation, including coolant temps, boost, intake air temps, etc. And if the vehicle happens to throw a code, it will help you diagnose it and assess the severity.

 

[LG_123]

If you're not already doing so, consider running a ELM327 Bluetooth OBD adapter and Torque app while towing. It gives great info on engine operation, including coolant temps, boost, intake air temps, etc. And if the vehicle happens to throw a code, it will help you diagnose it and assess the severity.

That looks interesting. I already have a Fixd in the OBD port but I could swap them out depending on whether I'm towing and getting error codes.

 

[chuck s]

I've not found any reason to second guess the transmission in either of my Gen 3 Expeditions towing a 6000 pound travel trailer here in the eastern mountains in WV, PA, and VA. They both have 6-speeds not the newer 10-speed but it shouldn't matter. I let my gears "shift for themselves" without issues. Tow haul asssists in the down-hill sections after a brake application. No unusual engine or transmission temperatures.

-- Chuck