You should have bought a Dodge if you wanted a loud exhaust break and a slow truck. I love my quiet Ford that tows my 38+ foot fifthwheel fast.

 

Marketing is a beautiful thing...unfortunately it usually involves a "spin" that has little to do with reality......after all we have to remember the "king really was naked" regardless of how the tailor spun it.....

 

What I havent read in these explanations is how the tow/haul mode is (this MY year at least) a combination of EB and the trasmission down shifting. Here is my laymans take. correct me if I am wrong. PaintedHorse, you are very proficient at trailering and are quite capable of running the gears manually. For those occasionally trailer pullers, this is how I have always used it:

When you are hauling a "heavy" load
Place in tow/Haul

1. When your speed is increasing and you desire a decrease, tap brake once or twice until EB engages.
2. As you need a further decrease, tap brake again or a little harder to tell the EB, you desire a slower speed and so on.
3. If on a long downgrade, I have also found using the cruise helps maintain speed also without having to manage the gears manually.

This may be the dumbed down version, but it works for me.

 

My towing conditions are very similar to Painted Horse's. My rig weighs 22200 pounds when ready to go camping. I have run the big hills east of Pittsburgh, Pa on US 30. These are 9% grades that are more than 3 miles long.

My operating procedures are very simple;

Tow/Haul mode engaged
Climb hill at 65mph...you could go faster because the truck has so much power
As I approach the crest of the hill I allow speed to slow to 50mph
At the very top, I tap the brake pedal one times to switch on the EB
I then enjoy the steady 50 mph descent to the bottom...no service brakes needed

I accept the fact that my truck likes 50 mph or a little less when descending. It is the sweet spot for my rig. It only took 2 descents to figure out the parameters that worked for me.

Regards

 

O.K. Im guessing 50 mph is the sweet spot with 3.73 or 4.10 gearing? Do you know what gear the trucks in....thanks for the plain terms, didn't know about pressing the brake once or twice........Blah Blah Duramax..Blah Blah Dodge......

"THE NEW FORD SUPERDUTY. THE BADDEST TRUCK ON EARTH!"

That's all I've got to say about that....

 

Chris

My truck is a F350 SRW with 3.55 gearing. Maybe someone with a dually will add to the discussion.

Regards

 

CabinDoc, I've used it in various ways,

Set the cruise and forget. The cruise will down shift to the appropriate gear. You may have a 5-10 mph run up above the set speed, Depending on what speed the cruise is set for. This has worked well for me on US-40 coming down Daniels Canyon into Heber city. I set the cruise speed at 55 mph at the summit. (It's a 60 mph road) The truck will gain in speed in the upper streatchs of the canyon where it is steeper. all the down shifting is done by the cruise and I end up in 3rd gear going 65-68 mph.

I have also left it in cruise and used the +/- buttons to down shift to lower gears. Tapping the brake would diengage the cruise control.

On some 50-60 mph roads that have 40 mph curves. I set the cruise at 50 mph and as I come to the curve, I use my brakes ( disengaging the cruise) to slow to 40mph. In 2nd gear I will roll up to about 45 mph. If that is fast enough I leave it there. If not, I'll let the truck upshift to 3rd and use the brakes again at the next 40 mph curve.

I don't think there is a a Right or Wrong way. Like many things in our trucks there are multiple ways to utilize the features. Choose the method that works best for your load, grade, altitude and speed limit.

 

I agree with all the observations after taking the 12K 5ver out a week ago. You have to be proactive with the entrance speed on the downhill or it will take wheel brakes to get things settled down.
BTW thanks for the tip of being able to use tap shift to set the gear for descent, I had heard that manual shift mode defeats the EB and was using the brake pedal to set downshifts.

 

Another good post Painted Horse. Well thought out and written.

My association with the EB/TH is similar to yours. I'm heading to work so I don't have much time right now, but here is my understanding.

Just shooting from the hip here, but as I have posted previously on this subject, as I understand the EB process, FOMOCO reinjects exhaust into the combustion chamber to starve the combustion process. Thus reducing any power being generated even while coasting, or against compression. While this is a controversial explanation, it is FOMOCO's explanation. See the attached video.

2012 Ford Super Duty | View Super Duty Features | Ford.com

So, if exhaust is being introduced into an already hot envoirnment, it seems to me that it would restrict the fresh air intake thereby increasing the pyros. Not sure if this answers questions or just raises more.

 

This seems to be a common misunderstanding; this is not how the system works.

Modern diesel engines such as the 6.7L PSD inject no fuel while coasting. The problem is that because there is no throttle plate used at this time like there is on a gas engine there is no method to restrict the constant motion of the engine. As each piston comes up on the compression stroke, no fuel is injected but the compression pressure pushes the piston back down with very little braking effect.

An exhaust brake operates by increasing exhaust backpressure so as to resist motion of the engine while coasting downhill. No fuel is injected, but due to increased pressure in the exhaust system the travel of the piston is resisted and the vehicle speed is retarded. NO exhaust is introduced into the combustion chamber, this would have no braking effect as it would be just as inert as air would be without fuel.

No mention of introduction of exhaust gasses is mentioned here. This system simply uses the turbo veins to resist flow and create backpressure in the exhaust system.

From HERE:

And from our own Painted Horse on another forum HERE:

 

That clears it up for me

 

Quite a bit to take in for sure. Thanks for all the knowledgeable posts.

B

 

It is interesting that you noticed this as well, I saw it but I had know idea why it was like that. I don't do a lot of heavy towing and even less with big grades here on the prairies so it was tough to replicate.

I was watching the back egt temp to see when I was regening. Seems I've got more questions than answers now that I've watched that for a couple of trips.

 

What product are you guys using to get EGT temps? Or did you install additional EGT gauges?

 

My boss bought me a DashDaq XL to keep an eye on things. Plus he knows I like toys like that. It's just for the gauges I don't have any programming mods. I love that thing, there are lots of parameters that can be monitored.