Engine Braking

[linux3]

Maybe this isn't the place for this question but...
As you can see I have a 2017 Silverado 1500m Z71. Factory tow package.
I have read the manual about using engine braking when towing. I've read it 4 times and am still scratching my head. I'm a retired engineer and maybe I've been away too long but I just don't understand.

Someone who uses this feature, could you explain?

[sourdough]

Is the manual referencing the gas or diesel engine??

[rhagfo]

Originally Posted by sourdough

Is the manual referencing the gas or diesel engine??

OP stated 1500 must be Gas

[sourdough]

Originally Posted by rhagfo

OP stated 1500 must be Gas

Yes, it would be gas and that's why I asked the question. He said he was reading he manual about engine braking but nothing about engine braking with a gas engine. Didn't know if his manual contained gas only info or for gas and diesel.

[hankpage]

I would imagine the difference is engine braking with a gas engine (down shifting) and exhaust braking with a diesel engine equipped with an exhaust brake. JM2¢, Hank

[Pull Toy]

These days it seems that "One size fits all" manuals are common. They're cheaper to produce, but can be confusing, and sometimes have conflicting info.

To the best of my knowledge, the "automatic" engine braking occurs only in diesel engines equipped with "Tow Mode". Kind of like the old "Jake Brakes" on the big rigs. The back pressure of the engine at idle transfers to the drive train causing a braking action when the brakes are tapped. The engine downshifts and causes engine drag.

It won't stop you, but it will slow you down, and takes a bit of the load off of the brake system.

Good Luck!

[Tbos]

Actually in the Silverado gassers there is engine braking. It's accessible through the menus. My 1500 had it and previous Sierra 1500 had it too. Basically when activated it down shifts automatically to use the engine to assist the brakes. If you go to the Silverado forums they can tell the specifics.


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[kksfish]

Yeah its confusing......my 2500 seems to work in tow mode WITH cruise engaged!

[Outback 325BH]

I just downshift mine so I haven't looked into any automatic engine braking... however with the cruise engaged the vehicle knows the speed you want which would make it easier to decide when to brake.

My wife's Edge will downshift automatically while going down a hill with the cruise engaged... in order to maintain speed.


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[hankpage]

Originally Posted by kksfish

Yeah its confusing......my 2500 seems to work in tow mode WITH cruise engaged!

That is the cruise control keeping the idle up high enough maintain some back pressure trying to maintain the set speed. Cruise will help a diesel hold back a little bit down hills. Applying a little throttle will do the same.

[66joej]

We have a 2013 Ram 1500 5.7 with the new at the time for Chrysler 8spd. trans. When towing our TT and the trans is in towhaul it will downshift (I never use cruise control when towing). This causes what can be called engine braking. It has the factory tow pkge. with built in brake control. It does slow the rig down. JMO

[Tbos]

In my 2014 Silverado LT CC 5.3 gasser I could disable it through the menu or when it initially activates. It activates when towing and you release the gas or hit the brake to start slowing down. At least that is what it did on mine.


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[CrazyCain]

When i am in TowHaul mode with my Silverado and start to slow down, it kicks down to a lower gear as i start to slow down to help...

[linux3]

Bad choice of terms and I have the 5.3L gas engine.
Kick Down mode vs. Range Selection mode.

So, I'm pulling my TT down a hill. Do I select Range Select to use compression braking or is Kick Down mode doing the same thing?

[xcntrk]

In the gassers, engine braking is nothing more than transmission downshifting to make better use of engine compression to help slow the rig. Usually this is universally built into the Tow/Haul transmission mode. On acceleration and/or cruise the rig holds the current gear longer to make use of power in the higher RPM's. On deceleration the rig anticipates slowing and downshifts at a quicker rate to slow.

In the diesels it's a whole other story. All that transmission tow/haul stuff still exists and is used, but the turbo diesel motors also use what's called an exhaust brake (not to be confused with compression brake - aka Jake brake). This is feature of the turbo that uses a variable vein system to increase the exhaust pressure by restricting the outward flow through the turbo. The result is nearly identical to compression brake but done so using the exhaust instead. It's an odd feeling to get used to when the exhaust brake on my rig is in full spool running down a hill, I'll register 10+ psi of boost pressure even though I have zero throttle input.

[bsmith0404]

Everything I can find on the engine braking is just as what has been said, the transmission downshifts and uses the engine compression to maintain speed and reduce brake use. The truck also has a grade braking feature that monitors brake use to calculate brake temps and will do the same things to reduce braking. Basically, with both features, it's the computer monitoring what you are doing and making shift point changes to use the engine to assist with braking to reduce brake temps, saving your brakes and preventing them from overheating, or at least reducing the risk of them overheating.

[Desert185]

Living near the Sierra Nevada I see brake lights a lot with not much effort to downshift. Downshifting to use engine compression braking makes a big difference in saving your brakes for when you might really need them.

WRT diesel engine brakes, some of us have a Pac Brake style with a butterfly valve mounted on the aft side (exhaust side) of the turbo (EGT increases with actuation). No variable vanes. No increase in boost when using the exhaust brake and no down shifting in conjunction with the actuation of the exhaust brake unless done by the driver (like me with a stick shift). Its a pretty simple system that requires maybe more driver involvement and the option to not have a downshift everytime the exhaust brake is actuated, which might be desired given certain road conditions.

[flybouy]

Originally Posted by linux3

Maybe this isn't the place for this question but...
As you can see I have a 2017 Silverado 1500m Z71. Factory tow package.
I have read the manual about using engine braking when towing. I've read it 4 times and am still scratching my head. I'm a retired engineer and maybe I've been away too long but I just don't understand.

Someone who uses this feature, could you explain?

As has been stated it is designed to down shift the transmission. Before this feature us "old timers" did this manually in mountainous terrain. We recently returned from a lengthy trip and traversed the Allegheny mountains in WV where 10% grades were the norm. The engine braking kept the descent under control with very little need to apply the brakes. The key is NOT to crest the top at a high rate of speed or let your speed creep up on you. It's a lot easier to drop a little speed than a lot. Brakes convert momentum (speed) to heat. Applying hard braking with constant application creates too much heat for the slow speed (and therefore low air movement) to dissipate leading to brake failure and a quick but deadly short cut to the bottom of the hill.

[Ken / Claudia]

I have a question and post #15 says what I think. But, newer gas trucks may be different than any I have had or drove. There was never engine braking it was the transmission locking out higher gears. For many years this was a aftermarket tranny and as I know mid 2000s trucks from factory started having them. You step on brakes or turn on a switch that locks the transmission into a lower gear. And that prevents the engine from higher rpms. I see now those are in diesels also. So, is there something really different than that.