7.3L F350 Towing??

[LetsGoBrandon]

Download Forscan and increase the output setting in the driver mod section.

 

[J_Man]

How is a 10R140/7.3 gas (2024) put in tow-haul mode? I don't see a button for that.

Multiple settings on 2024 King Ranch… there S h would be a selector knob for various driving modes… icons show up along the bottom of the driver’s display.

 

[J_Man]

Odd. I am not aware of any gasoline engine equipped specifically with an engine brake.

What you may be experiencing is simple compression braking. These trucks' PCM's transmission controls are fairly sophisticated and will hold the gear you're in when it senses a descent.

Either way, the 7.3 gas Godzilla is a tremendous workhorse. It is most definitely de-rated when advertised at 430HP/485 lb/ft... it's closer to 500/525 and capable of much more w/ simple fuel and spark tuning let alone exhaust then additional hardware tuning (cam, intake, tb, etc).

Trust me - it is engine braking.

I've never experienced anything like it.
RPMs sky-rocket & fuel consumption goes to zero.


J_Man

 

[LetsGoBrandon]

As far as I understand you're referring to gear braking or simply downshifting. Which is extremely effective with the 7.3, 10 speed and 4.30 combination but not quite what the diesel gets.

I believe what Apples was referring to is either an exhaust or compression brake. Neither of which are available on the 7.3 and both systems are in fact superior at slowing heavy loads.

(Insert that's what she said remark)

 

[J_Man]

Well I probably need some tutoring in vocabulary… I'm not sure how to differentiate “engine braking” from “simple compression braking”.

But it is quite unique in my limited towing experience with gasoline engines.

Whatever you name you give it — it is extremely effective.


J_Man

 

[J_Man]

Odd. I am not aware of any gasoline engine equipped specifically with an engine brake.

What you may be experiencing is simple compression braking. These trucks' PCM's transmission controls are fairly sophisticated and will hold the gear you're in when it senses a descent.

Either way, the 7.3 gas Godzilla is a tremendous workhorse. It is most definitely de-rated when advertised at 430HP/485 lb/ft... it's closer to 500/525 and capable of much more w/ simple fuel and spark tuning let alone exhaust then additional hardware tuning (cam, intake, tb, etc).

I'd like to learn more about “spark tuning”.

J_Man

 

[Apples]

That's right.

Gasoline engines are not fitted w/ "engine brakes", for example, a Jacobs "Jake" Brake that interrupts intake or/and exhaust valve (Stages 1, 2, or 3) operation in big diesel engines, effectively adding a second compression stroke to the four-cycle deal. Stages 2 or 3 add a suction cycle in combination when both intake and exhaust valves are kept closed.

The diesels in our 3/4 and 1-ton trucks (and some other diesel-engine vehicles) can have an "exhaust" brake, where the entire engine's exhaust flow is throttled.

^ ^ ^ "engine brakes"


Engine braking in a gas engine, on the other hand, is compression braking and that is achieved by simply closing the throttle/lifting off the gas pedal.

Our trucks in Tow/Haul (as well as gas engine'd 1/2-tons that have a "Sport" mode) will downshift when certain brake pedal pressure is sensed by the PCM and/or when the PCM's inclinometer detects a downhill descent.

blah blah blah

Cheers

 

[Blade420Play🔪🏆]

That's right.

Gasoline engines are not fitted w/ "engine brakes", for example, a Jacobs "Jake" Brake that interrupts intake or/and exhaust valve (Stages 1, 2, or 3) operation in big diesel engines, effectively adding a second compression stroke to the four-cycle deal. Stages 2 or 3 add a suction cycle in combination when both intake and exhaust valves are kept closed.

The diesels in our 3/4 and 1-ton trucks (and some other diesel-engine vehicles) can have an "exhaust" brake, where the entire engine's exhaust flow is throttled.

^ ^ ^ "engine brakes"


Engine braking in a gas engine, on the other hand, is compression braking and that is achieved by simply closing the throttle/lifting off the gas pedal.

Our trucks in Tow/Haul (as well as gas engine'd 1/2-tons that have a "Sport" mode) will downshift when certain brake pedal pressure is sensed by the PCM and/or when the PCM's inclinometer detects a downhill descent.

blah blah blah

Cheers

Aka "grade braking" on GMCs.

 

[Apples]

I'd like to learn more about “spark tuning”.

Any number of aftermarket "tuners" will have various spark timing profiles to choose from. That's what "spark tuning" is. Usually, this is in conjunction with altered fuel injection delivery mapping.

I don't typically use any aftermarket tuning on my gas rigs because modern Fords are very well mapped as they come from the factory.

These things make as much power as I need, therefore I just learn how these trucks "like" to be driven and adjust my style accordingly. No tuners, no pedal monsters, no nada. Nicht. Naught. Nothin'.

Just better dampers, a freeflow stainess exhaust system, a little auxilliary lighting and a leather-wrapped steering wheel (my XLTs needed 'em) is all I like to do. Oh, and tires! sometimes wheels.

 

[Phillbo]

Trust me - it is engine braking.

I've never experienced anything like it.
RPMs sky-rocket & fuel consumption goes to zero.


J_Man

Sounds like tow haul dropping gears.

 

[J_Man]

Apples - Thanks for the excellent explanation!

The transmission (w/cruise control engaged) does down-shift on the descent.

RPMs jump up to 5,000 or maybe 5500, and the fuel economy gauge pegs out over 30-mpg.

The first time experienced it I was shocked but when I researched FORD’s towing guidelines this is how the system was designed to perform.

My RV is relatively light (6K dry, 7.5K fully loaded for a 5-week trip). The Godzilla holds at my cruise speed going up and going down.

Most of the passes I travel have a posted speed limit of 55-mph… some are less. I was used to switching to manual on passes in my F150 EB, but I am now convinced Ford got this right in the 7.3L.

And I agree about engine tuning… I personally have no need to change anything.

Thanks again - great explanation.


J_Man

 

[pickleknuckles]

Odd. I am not aware of any gasoline engine equipped specifically with an engine brake.

What you may be experiencing is simple compression braking. These trucks' PCM's transmission controls are fairly sophisticated and will hold the gear you're in when it senses a descent.

What you described is engine braking, what they're not "equipped" with is an exhaust brake.

 

[Vetdoc81]

I can tell you that 7.3 has no problem with towing. I tow a 14k 5th wheel full time as I live in it. Towed all over US with it and up 8-10% grades and at 12,000+ feet up in Rockies. Whatever he was towing... they either don't know how to drive or the weight is easily over 18k. It will scream up a mountain if I make it but I don't and don't need to even passing tractor trailers up 8% at 45 mph at 3-4k rpm's maximally... not red line at 6k!

 

[J_Man]

I can tell you that 7.3 has no problem with towing. I tow a 14k 5th wheel full time as I live in it. Towed all over US with it and up 8-10% grades and at 12,000+ feet up in Rockies. Whatever he was towing... they either don't know how to drive or the weight is easily over 18k. It will scream up a mountain if I make it but I don't and don't need to even passing tractor trailers up 8% at 45 mph at 3-4k rpm's maximally... not red line at 6k!s

 

[J_Man]

Same experience for me, except my RV is much lighter.

My first experience towing a Travel Trailer in the Rockies was with a 1979 F250 4WD with the 400ci V8… max speed going up was 35-mph.

No comparison to the 7.3L on the same pass - 55-mph on cruise (posted speed limit) and I'm sure I could have gone to 65-mph or better.

For me, the delightful surprise is the descent - again, cruise control going down the pass and just let the truck hold the speed and optimize the fuel consumption.

J_Man

 

[RedZilla]

This is a long shot. Have you checked the break away switch for the trailer brakes? If it’s gotten pulled (activated) he may be towing with the trailer brakes fully applied.

 

[Phil314]

The diesels in our 3/4 and 1-ton trucks (and some other diesel-engine vehicles) can have an "exhaust" brake, where the entire engine's exhaust flow is throttled.

Engine braking in a gas engine, on the other hand, is compression braking and that is achieved by simply closing the throttle/lifting off the gas pedal.

Our trucks in Tow/Haul (as well as gas engine'd 1/2-tons that have a "Sport" mode) will downshift when certain brake pedal pressure is sensed by the PCM and/or when the PCM's inclinometer detects a downhill descent.

Compression braking on modern gas trucks works far better than in the past.
With older trucks and newer trucks when not in tow/haul mode, when you lift off the accelerator pedal, the TCM will unlock the torque converter and that allows the truck to coast. For normal driving this is what you want.

With a newer truck in tow/haul mode, when you lift off the accelerator, the TCM will keep the torque converter locked. This creates a lot more compression braking by itself, since the wheels are still connected directly to the engine. Then as @Apples said, by braking, the PCM can throw in a couple downshifts and bring the rpms way up. Causing a lot more compression braking.

These 2 things working together are very effective. Not as good as a diesel exhaust brake, but probably 70-80% of the way there. And good enough for most of us mere mortals.

 

[ACL]

I have had one similar experience in my '23, 7.3, 4.30s. Towing about 8k on a steep grade. Do not recall what gear it had dropped to, but it felt just like limp mode until I got to a turn and it downshifted again.

Have not been able to replicate it again.

Second 7.3 truck, my other, a '24 with 3.73s has towed way more and never had this type of an issue. Made me want to get rid of it. But the baja leather will not let me.

 

[Apples]

These 2 things working together are very effective.

Correct. I've been abreast of every Ford automatic transmission improvement since the C4!



...and since the 1990s made a living using my commercial driver license in everything from fork lifts, F550s, F650s, 3-axle straight trucks (Peterbilts, KW) and 18-wheelers.

It was in the F550s, in Ford vans, etc that I experienced the evolution from AODs, AOD-Es, five speeds, six speeds (both manual transmissions and automatics).

Being a motorsports enthusiast (corners more than 1/4 mile) but still driving automatics is where I learned the value of improved valvebodys for tighter shift calibration, the variety of pre-lockup torque converter stall speed, etc... I always liked a tight trans and converter specifically for use a "road car" - I never liked loose converters (I wasn't drag racing) because I liked the engine compression braking.

With my senses tuned into that realm I was perhaps extry aware of when lockup torque converters entered the scene.

Today's transmissions in these trucks are superb, mostly.

Thanks for your post!

 

[Fordtruck7]

How is a 10R140/7.3 gas (2024) put in tow-haul mode? I don't see a button for that.

I have a 2024 F250 with 7.3L gas. Putting it in tow haul mode is done by rotating a dial. The dial is centered in the 4x4 selection of buttons to the right of the steering closer to your right knee. As you rotate it look at the dash in the center between the Speedo and Tach. you will see selections pop-up there as you rotate the dial.

Side Note: I have the 4.30 diffs and have only had mine now for about 2 weeks. It is a stump puller. I road tested my bumper pull square parachute of a camper uphill at (it was a short test only), but briefly hit well over 85mph. Yeah I know all the bad things that could happen, but I just had to see what it would do. It is officially a 29foot camper measuring stem to stern about 34 feet. I would guess it was probably about 8k lbs on the test. This engine is a monster. I use them at work on 26K box trucks and an F350 stakebed routinely pulling up to 16k lbs. I am a newbie here, but I agree with the forum. Something is off on your 7.3L.