So Tell Us About Dynamic Fuel Management in Your 2019 T1's

Eds240z06 · March 7, 2019

24 minutes ago, Cpl_Punishment said:

But it's only 2 gallons smaller. Do you drive the truck on weekends? Is it filling up after 8 days of driving vs 14, or vs 10?

No weekends. Sorry I wasn’t clear before. My calculations was off of what I wrote vs what I was thinking. It’s actually 8 vs 10 days.

Sierra Dan · March 7, 2019

First 2019 T1 Dynamic Fuel Mgmt. GM truck casualty...….

Any other T1 owners hearing noise?

OnTheReel · March 7, 2019

Nothing like that guys sound, just the usual injector ticking. I have exactly the same amount of miles on mine as he does.

I really hope it’s an isolated incident. If a dealer has to be pulling heads on mine it’ll probably get traded. I don’t really trust anyone screwing around with it like that and it would never be the same for me.

ShamrockShooter · March 10, 2019

If you use the knob on the top left of dash to put it in sport mode or tow mode does it disable DFM or autostop?

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2011Chevy · March 10, 2019

1 hour ago, ShamrockShooter said:

If you use the knob on the top left of dash to put it in sport mode or tow mode does it disable DFM or autostop?

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I’ve been trying to determine this also but haven’t seen a clear answer, granted I don’t own one of these 2019’s yet either.

I posted this in another thread but thought it may be useful here also:

I test drove a 19 trail boss LT in moderate traffic

conditions for part of the drive, and noticed the hard downshift twice. It felt exactly the same as the way my ‘17 tahoe 6sp tranny shifted BEFORE I disabled the AFM. I also felt the torque converter locking/unlocking with the cylinder deactivations.

Test drove a RST and LTZ a couple of weeks later with far less traffic and higher speeds and felt no tranny issues.

I really like these new 19’s, but am hesitant to buy one with this particular ongoing issue. Seems that disabling DFM may solve the majority of this, but no one yet has products available to do so. I can tell you that my ‘17 tahoe drives like a completely different vehicle operating on all 8 cylinders 100% of the time.

I had a 14 with the 5.3 and 6sp that was at the shop 3 different times for hard up shifts/downshifts that could not be resolved (“transmission operating as normal” per dealer). I traded that piece of junk in less than a year, don’t want to be in that position again!

Daverado · March 12, 2019

On 3/10/2019 at 10:54 AM, ShamrockShooter said:

If you use the knob on the top left of dash to put it in sport mode or tow mode does it disable DFM or autostop?

Tow/haul does disable auto-stop-start, but Tour, Sport, and Off-Road modes do not.

There's also this:

Edited March 12, 2019 by Daverado

Thejet07 · March 12, 2019

I’m getting a bit of vibes in my floor board/pedal on the highway. It’s a bit annoying. I would love to disable and have v8 all the time. It’s weird because it’s on and off throughout the ride. Even on a flat road

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eppieguy · March 13, 2019

I've spoken to Range Technologies and they are currently working on the DFM disable, hopefully soon to be released but they will not commit to a date.

tlwilson · April 14, 2019

Has anyone changed to an aftermarket exhaust? If so, how does it sound when the DFM kicks in?

Robwcormack · April 17, 2019

On ‎3‎/‎12‎/‎2019 at 7:02 AM, Daverado said:

Tow/haul does disable auto-stop-start, but Tour, Sport, and Off-Road modes do not.

There's also this:

None of the modes disable DFM though

Wiggums · April 17, 2019

With all that talk about the DFM, I was a little concerned here but it's really overblown. It's not the same as the 2018's and before. My gas mileage is respectable, I get 25 going 55 mph and I'm very happy with it.

relevante · April 18, 2019

Does anyone know if L9 on the 6.2L 10 speed disables DFM? I drove around all day today like that for the first time and actually pushed the motor a bit more here and there as well, and so far am getting about 1 mpg better than I was before. I’m not feeling a bit of surging that I was feeling occasionally before either, so I think it is probably off. I also just installed a tonneau cover, and the engine is breaking in, so unfortunately it’s not a scientific study by any means but it seems to me to at least be an indication that it might not be helping me a whole lot. Or that L9 isn’t disabling it.

Trying to decide if I want the Range when it gets updated. I definitely want to kill Autostop. Was planning to keep DFM, but if the fuel savings aren’t noticeable, why take the risk with it, even if that risk might be relatively small at this point?

Edited April 18, 2019 by relevante

econometrics · April 18, 2019

I'm getting noticeably better MPG with my 2019 DFM vs. my 2007 AFM 5.3L. Especially on the HWY. I never, ever averaged above 20mpg with my 2007, only getting close if I was doing like 58mph for loooong stretches without stopping.

I'm getting 21-22mpg doing 75-80mph with my DFM 2019.

Also, I have not noticed any DFM vibration/shifts/etc.

The AFM on my 2007 was incredibly noticeable when it went from V8 to V4, so maybe I'm not as sensitive to anything the DFM is doing.

relevante · April 18, 2019

26 minutes ago, econometrics said:

I'm getting noticeably better MPG with my 2019 DFM vs. my 2007 AFM 5.3L. Especially on the HWY. I never, ever averaged above 20mpg with my 2007, only getting close if I was doing like 58mph for loooong stretches without stopping.

I'm getting 21-22mpg doing 75-80mph with my DFM 2019.

Also, I have not noticed any DFM vibration/shifts/etc.

The AFM on my 2007 was incredibly noticeable when it went from V8 to V4, so maybe I'm not as sensitive to anything the DFM is doing.

I don't have any huge issue with the drivability, although I do think I'm noticing it occasionally. If it appears to consistently save even 1-2 mpg though, I'll probably keep it active, but it's interesting to me that I'm so far seeing the opposite. I haven't done any long highway cruises yet though. Will be doing a little of that in the next few days, so it'll be interesting to see how it seems to respond to that. I am a little gun shy because my dad had a major AFM-related issue in its early days. It took a prolonged battle, but he did end up getting an engine replacement though and still has the truck (with AFM long since disabled).

If I get anything over 20mpg doing 80mph like you are on these upcoming highway runs, with or without DFM, I'll be thrilled (I have the 6.2L, so it'll be interesting to see). I usually only got around 22mpg on trips with my Mazda CX-9, which weighed about 1500lbs less and had a 2.5L turbo 4. Although I tended to spend a lot of time over 80mph in it on the highway too, so that's not a totally fair comparison either.

relevante · April 22, 2019

OK, just did about a 400 mile short road trip this weekend and it did change my view on the DFM. It’s hard to do a direct comparison with/without because on the highway the L9 seems to modify shift points in a way that matters and is most likely hurting things. But once I noticed that I just stayed in D and let it do its thing and got an average of 19.5MPG on a trip involving a combo of hilly interstates going mostly 75+, 2 lane (hilly) roads, and a little in town stuff here and there. On the way home I pushed it pretty hard too, climbing some long grades at 80-85mph and generally just not thinking about economy at all, and even in those 25 mile windows on the DIC the average stayed over 18mpg. I’m definitely impressed. I’d love to go do the same trip with DFM disabled and see how it does. And maybe I will buy a Range to do some testing with when they’re all sorted, but for now I’m not worried about it.