Engine braking on 2017 F150 5.0L

[plasticmaster]

I have a 2017 F150 with the 5.0 engine. When I tow my TT in tow haul mode, it seems to me that Ford has overdone it with the engine braking. As I apply the brakes, it downshifts really hard and revs really high to the point of making me wonder if it could damage the engine or transmission. On my last trip, I would disengage tow/haul when I knew I was getting ready to hit the brakes. Should I be concerned about this, or just let it do its thing?

[Grit_dog]

mkirsch wrote:

Turtle n Peeps wrote:
Modern computer controlled trucks do not over rev. It's impossible because of the computer.

Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.

Let it rev.

That's true when you're stomping on the go pedal, but is it when you are being pushed down a grade by a big trailer with your foot off the gas?

When you're being pushed you can cut the ignition all you want and it's not going to limit anything. The only thing that will bring RPMs down is an upshift, and I don't know of anyone who has let their rig go that far to see what would happen.

For science, I've let my 8.1L/Allison go to 5000 before I hit the brakes, and there was no indication of it upshifting or doing anything but dropping another gear in a futile attempt to maintain speed by engine alone.

You may be right. Late 02, maybe for 03 models, a grade braking algorithm was added to the Alli’s brain.
It would overrride the grade braking at 5000rpms on the 8.1 and 4800rpms on the 6.6 and command an up shift if rpms climbed beyond those points.
However it would never try to downshift again at “redline” rpms.

While the Alli 1000 was really the pioneer for “smart” transmissions in light duty trucks, it still required or requires the operator to have a little common sense and act accordingly.
Newer vehciles and transmissions are even smarter and more refined, taking away a bit more necessity that the operators have some active gray matter floating between their ears, but at the end of the day, if you’re literally adventurous enough or ignorant enough to test how well the engineers idiot proofed your transmission, you might be left on the side of the road somewhere. Either rubber side down if you finally decided to use the service brakes soon enough or rubber side up if ya continued to tempt fate until it actually answered your call! Lol

Now, recent models with adaptive cruise and active collision avoidance/auto braking, have taken it one step further before fate comes knocking. But like any mechanical item, someone somewhere is bound to be ignorant enough to break it by not braking it….

[Turtle_n_Peeps]

mkirsch the ECM will tell the tranny to upshift and force an upshift.
If you are over the ECM's RPM limit and try to manually downshift, the ECM won't let that happen. There is no mechanical link from the shifter to the tranny anymore. Hasn't been for many, many years.

Long gone are the days of mechanical transmission governors and vacuum modulators.

Ever notice that a lot of tach's don't have any yellow or red lines painted on them anymore?

[mkirsch]

Turtle n Peeps wrote:
Modern computer controlled trucks do not over rev. It's impossible because of the computer.

Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.

Let it rev.

That's true when you're stomping on the go pedal, but is it when you are being pushed down a grade by a big trailer with your foot off the gas?

When you're being pushed you can cut the ignition all you want and it's not going to limit anything. The only thing that will bring RPMs down is an upshift, and I don't know of anyone who has let their rig go that far to see what would happen.

For science, I've let my 8.1L/Allison go to 5000 before I hit the brakes, and there was no indication of it upshifting or doing anything but dropping another gear in a futile attempt to maintain speed by engine alone.

[JRscooby]

Lantley wrote:

Turtle n Peeps wrote:

Lantley wrote:

I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.

Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.

That all sounds good, I don't dispute your claim. But that 2007 truck would definitely overheat if you let it. I managed to control the overheating by not letting the truck rev as much on steep declines.
Again it had an after market exhaust brake that could had been faulty and ultimately caused the problem.
My 2019 has a factory exhaust brake and does not have that issue.

To slow a vehicle, a lot of energy must be transformed to heat, and dissipated. Now does it go out thru brakes or engine and drivetrain?
Personally, I know engine temps will drop fast when jake shuts off, and transmission/rearends will cool quickly if soft-pedal for few miles, and the system designed to stop is still in best working order if faced with emergency.
Now something that many overlook is how to reduce the amount of energy that must be dissipated. It takes much less braking, service or engine, to reduce speed from 40 to 30 than 60 to 50MPH. Let speed drop to well below safe as you near start of downhill, then hold the lower speed until near bottom.

[Lantley]

Turtle n Peeps wrote:

Lantley wrote:

I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.

Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.

That all sounds good, I don't dispute your claim. But that 2007 truck would definitely overheat if you let it. I managed to control the overheating by not letting the truck rev as much on steep declines.
Again it had an after market exhaust brake that could had been faulty and ultimately caused the problem.
My 2019 has a factory exhaust brake and does not have that issue.

[Turtle_n_Peeps]

Lantley wrote:

I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.

Any modern diesel truck or gas truck for that matter, cuts all fuel off to the injectors while going down hill. There is no heat being made because there is no combustion going on. This has been going on since 1994.......at least for GM.

[Lantley]

Turtle n Peeps wrote:
Modern computer controlled trucks do not over rev. It's impossible because of the computer.

Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.

Let it rev.

I'm not suggesting the OP has a problem with their truck. But I can attest to my 07 LBZ Duramax overheating due to excessive revving on steep declines. Is a 2007 a modern truck?
The exhaust brake was aftermarket which may have been the root of the problem. Nevertheless the tranny would and did overheat if you let it.

[wnjj]

Turtle n Peeps wrote:
Modern computer controlled trucks do not over rev. It's impossible because of the computer.

Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.

Let it rev.

Truck pulls hold these meetings too. I used to help my uncle who owned a pulling sled business. There was one local truck that had a moderately built 454 that spun 9000 RPM when pulling.

[Turtle_n_Peeps]

Modern computer controlled trucks do not over rev. It's impossible because of the computer.

Anybody that is worried about over reving their "modern" truck is worrying about nothing. They need to go a rev anonymous meeting. They are held at their local race track. I haven't been to any in a long time but when I did I took my 572 to 7,000 RPM time after time. And this thing has pistons as big as a small coffee can.

Let it rev.

[Grit_dog]

Boomerweps wrote:
A minor trick with the F150 10 speed on hills:
If you set the cruise control before the top of the hill going down, it will aggressively downshift to maintain speed 5mph or so above the set speed. I’ve not tried this towing.

It works towing as well. Until the revs can’t keep up with the acceleration. On a Chevy anyway, with the same trans.

Most newer transmissions with smart tow/haul do that as well. Even my clunky ole 68rfe.

[mkirsch]

Thinking about this more, and I'm wondering if you are expecting the truck to automatically maintain speed.

It doesn't work that way. If you get it into "grade braking mode" with much of a trailer on, and just let it go, it will keep downshifting and downshifting trying to maintain speed.

You need to use brakes, and you need to stay ahead of the transmission to keep it from overcompensating. Once it starts dropping gears and overrevving the only solution it to pop it out of tow/haul and start over.

[Boomerweps]

A minor trick with the F150 10 speed on hills:
If you set the cruise control before the top of the hill going down, it will aggressively downshift to maintain speed 5mph or so above the set speed. I’ve not tried this towing.

[valhalla360]

plasticmaster wrote:
I have a 2017 F150 with the 5.0 engine. When I tow my TT in tow haul mode, it seems to me that Ford has overdone it with the engine braking. As I apply the brakes, it downshifts really hard and revs really high to the point of making me wonder if it could damage the engine or transmission. On my last trip, I would disengage tow/haul when I knew I was getting ready to hit the brakes. Should I be concerned about this, or just let it do its thing?

As long as it's not redlining, you should be fine.

If you feel the need to hit the brakes, you really don't want to disengage the engine braking feature.

Try not to let the speed get too high early on. Much easier getting the speed down and under control doing 50mph on a road suitable for 40mph than letting it get up to 70mph and then trying to get it under control. That will help avoid some of the more extreme downshifts.

If you like manual control, you can leave T/H on and manually downshift but really no need. Once you get a feel for it, you can tap the brakes to make it downshift. I've gotten in the habit early on to do that rather than manually pulling the gear shift down.

[MFL]

Grit dog wrote:

MFL wrote:
On a steep downhill, with 10K pushing me, I prefer to not use t/h, and manually select gear I want to use. This works best for me, on long downhills, that also include lots of turns.

Jerry

Not sure I’ve seen a manual mode (+/- button) on any newer truck that will prevent further downshifting if the truck calls for it. Either slowing down below min speed for the top gear selected or in a grade braking scenario.
From the old 6 speed Fords that the OP has to new GM 10speeds.
They’re great at limiting up shifts to whatever top gear you want to maintain.

You are right, my 6R140 is not a six speed stick, and can/will do its own thinking when absolutely needed. It will hold me back on a lengthy downhill, in 3rd/4th. If rpm demanded an upshift, as in reaching redline, IDK? It's never come to that, as I just apply brakes as needed, but applying brakes does not downshift, when not using T/H.

Coming to a stop in manual mode, it will downshift on its own, but not as soon as when in drive mode. It will drop to 2nd when stopped, rather than 1st.

The OPs transmission, not the same, but should operate similar?

Jerry