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2025 Cummins Regen Observations

AH64ID said:
Why would you factor DEF into regen cost?
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So my logic:
- 3500 SRW mega or crew cab with ram box

- Comparing hemi vs diesel general use case
- I am more interested in range than mpg, but still a factor

- California fuel so 91 octane for the hemi
- CA funny diesel for the cummins - somewhat higher cetane, somewhat lower energy content compared to other places
- Assume 4 people on a trip with some stuff ( 1000 lbs ) but no trailer
- Driving 70 - 75 ish mph

- Some driving from sea level to 7 000 ft
- Some driving just sea level
- 30 gallon fuel tank

- Here, the price of diesel and gasoline are roughly the same, $5.50 vs 5.30 right now
- Price of DEF ~ $2 / gallon roughly
____________

So in theory ( 30 gallons of diesel ) x ( 20 mpg ) ~ 600 miles.

Info from this thread and others - regen will happen every 500 - 700 miles, so roughly 1x per tank

Regen takes 2.5 gallons of diesel + 1 gallon of DEF

So real range is really ( 27.5 gallons ) x ( 20 mpg ) ~ 550 miles

Fuel + DEF ~ $ 165 + $2 for def
__________

Hemi ( 30 gallons of gasoline ) x ( 15 mpg ) ~ 450 miles

No def used in that tank

Gasoline ~ $159
___________

So the diesel is still a good path, as long as the maintenance is viable.

That is as close as my guesstimating is right now - is that more or less in line with your thinking ?
 
HarryN said:
Regen takes 2.5 gallons of diesel + 1 gallon of DEF
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DEF is not used for regen. Regen cleans the soot out the DPF and DEF is used to reduce NOx in the SCR, two completely independent emissions functions.

2.5 gallons of additional diesel per regen is also not necessarily normal.
 
ZF.Transmission.Guy said:
IT might depend on your cluster option, but there should be an option to display the current gear in the settings. If not, you can just hit the - button on the steering wheel gear selection buttons, set max gear to 8th, and it will show your current gear as well
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Display Current Gear in settings never showed/worked as advertised in the Owners Manual. There's an AlfaOBD hack to turn it on, it's listed in our "Solved DIY" sticky.
 
Brutal_HO said:
Display Current Gear in settings never showed/worked as advertised in the Owners Manual. There's an AlfaOBD hack to turn it on, it's listed in our "Solved DIY" sticky.
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That's strange, it worked in all the development vehicles I was in later during development.
 
Braking down a steep *** grade with a big*** load. Also just more turbo brake because 13mph is cool but 5mph is even better.
 
PyroJoe said:
Braking down a steep *** grade with a big*** load. Also just more turbo brake because 13mph is cool but 5mph is even better.
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That is tricky because being lockup up at such a low vehicle speed risks stalling the engine if engine speed falls quickly. 5 MPH wouldn't ever happen due to not wanting to stall the engine. 13 MPH maybe, but unlikely. It would depend what vehicle speed you can achieve at ~3000ish RPM in 1st.
 
My CTS3 shows gear/lockup status on my 23 although it's not locked in this picture and obviously doesn't lock until a certain speed is achieved.
 

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PyroJoe said:
Ford does it. Nuff said.
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I would think by converter lockup at any speed below 10+ cause engine lugging putting excessive strain on the engine and potentially causing damage. So, I would imagine locking up the torque converter at 5 mph would compromise drivability and increase engine stalling not to mention the wear you're putting on the transmission. Ford HD diesel trucks generally do not allow the torque converter to lock up at speeds 10 or less mph. Someone would be liable for the trans when it goes to **** by doing so. I was taught that the torque converter is a feature that engages at higher speed often 40 mph just to eliminate slippage.
 
The TQ converter locking in 1st was definitely part of the original advertisement scheme and a huge bonus.

I do lots of slow towing up steep slow mountain grades where a locked 1st gear would greatly reduce trans temps and not cause any lugging.

Quite disappointing to hear it’s not working. I’d rather have lockup in 1st than extra gears.
 
AH64ID said:
The TQ converter locking in 1st was definitely part of the original advertisement scheme and a huge bonus.

I do lots of slow towing up steep slow mountain grades where a locked 1st gear would greatly reduce trans temps and not cause any lugging.

Quite disappointing to hear it’s not working. I’d rather have lockup in 1st than extra gears.
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Has it been shown somewhere that it doesn't lock up in 1st?
 
ZF.Transmission.Guy said:
Has it been shown somewhere that it doesn't lock up in 1st?
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The conversation in this thread today, including posts from you, indicates that it doesn’t lock up in first. If that’s wrong please tell us.
 
AH64ID said:
The conversation in this thread today, including posts from you, indicates that it doesn’t lock up in first. If that’s wrong please tell us.
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I said has it been shown, not claimed. I'm not trying to be combative or obtuse, but data is king. So far I've only seen claims.

Go to the top of a steep hill, lock it in first via the gear selection buttons, EB on, try in both tow/haul and without. Go down and let it run up to 3000+ RPM. That's the only way to know.



The wording is important in how it was advertised for "1st gear lockup".

Did it say the torque converter would be locked in 1st, or the TCC would lock in 1st gear?

Can you show an example of this advertisement? I'm assuming someone said it during a press release or marketing event. Their exact wording would clarify their meaning.
 
1st gear lockup should only mean one thing, TCC locks in 1st. Should is the key word, and that’s very subjective these days. Being able to lock the trans in 1st is lackluster and not new.

I’ll have to see if I can find it.
 
Xflight29 said:
I pull 15K up 7 % grades and can't imagine staying in first gear. The lowest gear I have ever had to manually go into was 3rd. But I'm thinking there might be something to this, so I will defiantly give it a shot.
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Is that with your 25?

That’s pretty close to 2nd with the Aisin, so that would be good news if it gets into 3rd that heavy.

For me the heavy hills with 3.42s and the Aisin needed 1st, sometimes 2nd.
 
AH64ID said:
Is that with your 25?

That’s pretty close to 2nd with the Aisin, so that would be good news if it gets into 3rd that heavy.

For me the heavy hills with 3.42s and the Aisin needed 1st, sometimes 2nd.
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Yes, with my 25, I took down my post after I thought about it for a minute.
 
scdo said:
I just made it back from my 700 mile trip from the dealer. While this is too early to be meaningful, I’m concerned on what I’m seeing.

Over the course of a 700 mile relatively constant 70-83 mph journey, I’m at 30% on the DPF gauge. Engine hours are approximately 17. I’ve also watched on my PID and can see that the soot load is slightly outpacing the engine hours in driving the % to regen.

My 2023 which had frequent regen problems (every ~120 miles around town) was able to keep to dash at 0% (after a fresh regen) on the other end of this journey.

Very surprised to see the brand new truck hit 30% but we also don’t know how the regen strategy on these operate yet.

Curious on others opinions but I’ll be updating my experience here. I’d also love to hear from other owners of the new engine.
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How are you monitoring the soot% on your 2025? My Idash and CTS3 neither capable of moniroting it quite yet. THey are hoping to get it done by august. Thanks!
 
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