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I'm not sure what you mean by "lean it out" in this context. I think you misread something I wrote.
You said "That reduced soot is due to a leaner mixture (makes sense with the fuel savings)."

And what I'm saying is when not being overfueled (or under low boost acceleration) a diesel always runs lean. There will always be excess air. It's simply a diesel fundamental. If you try and make it run leaner than it normally would then you just lose power or RPMs because the engine will seek equilibrium for lack of a better term. Yes, the VGT/VNT turbos help control boost better under a wide range of conditions, but you are not going to get a diesel to run even leaner while maintaining power/RPM. Fuel controls everything. Doesn't matter that there's a VGT, that relies on combustion. Increase boost without increasing fuel and you'll lose power.

Perhaps a better statement would've been reduced overfueling rather than a "leaner mixture" as the latter implies the engine is running leaner than its already-lean normal operation. If I lose weight but am still overweight then I'm not skinny or lean. I'm just less fat. Reducing fat mixtures to reduce soot isn't the same as running leaner, and while "leaner mixture" isn't technically wrong the wording has implications that don't really fit what's being done to control soot.

[----lean----stoichiometric----rich----]

Less-rich/fat vs leaner...Semantics? Perhaps...but sometimes that makes all the difference in making sure your point is getting across clearly. :)
 
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Ah! I get you.

"If you try and make it run leaner than it normally would then you just lose power... you are not going to get a diesel to run even leaner while maintaining power/RPM" Completely agree. Making less power is absolutely an option though, and it's one GDE/GM select under certain circumstances. With that lower power comes cooler temps (which corresponds with lower NOx) and a cleaner/less sooty burn; both of these statements are qualified with "below a certain lambda". This must be kept in check in order to meet the emissions testing criteria, which is GDE's party trick, and the reason I'm personally taking them seriously. The opposite is also true, and goes back to the power gains with diminishing returns I mentioned above.

Based on the information available:

  • Both GDE and GM have a min lambda of 0.8
  • GM's max lambda is 1.44 to GDE's 1.125
  • GDE makes more peak power
  • GDE gets better fuel efficiency

Fueling maps are RPM on one axis, and load on the other. For the available information to all check out, in certain circumstances GDE is necessarily running more fuel for a given RPM/load condition (this is a certainty any time GM's tune has a lambda > 1.125). For GDE to get better fuel economy though, there must also be RPM/load intersects where GDE runs higher lambda than GM. For GDE to also make more power, they must be running more fuel than GM at whatever that rpm/load condition is. Based on this, it necessarily follows that a given RPM/load intersect can have more or less fuel, generate more or less power, and generate more or less emissions (soot and/or NOx). The hangup is that there's more to it all than just fuel, and we have no information about those parameters... or nearly no information. I think GDE said they run the EGR less, there's some massaging of the injection frequency and timing, and I'm sure there's some turbo speed control going on (though I don't think it's been mentioned aside from preventing too much speed) to control the air.

I guess bringing it back around, one of the tradeoffs between the OEM tune and GDE is that GDE's is more peaky and abrupt compared to the smoother, wider range of the OEM tune. This is in part, I'm sure, due to the creature comfort/refinement angle GM was going for. Personally, I have no trouble with that. Prefer it even. It's fun; character. It's how I usually tune my DD cars.
 

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Ah! I get you.

"If you try and make it run leaner than it normally would then you just lose power... you are not going to get a diesel to run even leaner while maintaining power/RPM" Completely agree. Making less power is absolutely an option though, and it's one GDE/GM select under certain circumstances. With that lower power comes cooler temps (which corresponds with lower NOx) and a cleaner/less sooty burn; both of these statements are qualified with "below a certain lambda". This must be kept in check in order to meet the emissions testing criteria, which is GDE's party trick, and the reason I'm personally taking them seriously. The opposite is also true, and goes back to the power gains with diminishing returns I mentioned above.

Based on the information available:

  • Both GDE and GM have a min lambda of 0.8
  • GM's max lambda is 1.44 to GDE's 1.125
  • GDE makes more peak power
  • GDE gets better fuel efficiency

Fueling maps are RPM on one axis, and load on the other. For the available information to all check out, in certain circumstances GDE is necessarily running more fuel for a given RPM/load condition (this is a certainty any time GM's tune has a lambda > 1.125). For GDE to get better fuel economy though, there must also be RPM/load intersects where GDE runs higher lambda than GM. For GDE to also make more power, they must be running more fuel than GM at whatever that rpm/load condition is. Based on this, it necessarily follows that a given RPM/load intersect can have more or less fuel, generate more or less power, and generate more or less emissions (soot and/or NOx). The hangup is that there's more to it all than just fuel, and we have no information about those parameters... or nearly no information. I think GDE said they run the EGR less, there's some massaging of the injection frequency and timing, and I'm sure there's some turbo speed control going on (though I don't think it's been mentioned aside from preventing too much speed) to control the air.

I guess bringing it back around, one of the tradeoffs between the OEM tune and GDE is that GDE's is more peaky and abrupt compared to the smoother, wider range of the OEM tune. This is in part, I'm sure, due to the creature comfort/refinement angle GM was going for. Personally,
All this talk about fueling and power and no talk about timing and the different injections?
 

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I ran through most of a full tank since tuning and the DIC was off by about 1.7mpg. Reported 22.8 on the trip meter, hand calculated it was 21.12. We'll see how subsequent tanks do, but so far I can't complain. Looking forward to seeing how it does towing the boat and on a long road trip.

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All this talk about fueling and power and no talk about timing and the different injections?
"The injection events (pilots and main) along with fuel pressure, boost and temps all can influence the pressure curve shape. Managing this pressure pulse impacts longevity. If the increase is too early, you will pound bearings and potentially destroy a connecting rod. We try to keep the peak pressure under control and widen the range where work is done."

The compromises (or lack of) that come from timing are all pretty much addressed there, and that's what we're after. The OP is asking what tradeoffs one signs on to when a tune is installed. So far, you're trading some transmission smoothness for better feel and transmission longevity, and a smoother, more even throttle for better fuel economy/power with a bit more peakiness (which is also kinda fun, so not really a compromise). I think I got it all...
 

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Dropping the pilot injection at wot should net more power without pounding the bearings?
Yes it can. We measured a 10 bar drop in cylinder pressure by going main only at WOT conditions. The calibration of injection events are where it is at. We have past experience working with GM on some export projects. It seems they put some younger, inexperienced engineers on this platform and thus the refinement is not the best. The GM calibration changed completely in 2019 and looks like the folks in Torino, IT did the cal work on the newer models. This job was even worse and some of the OEM mapping looks like it was completed on an engine dyno and not even in a vehicle. The consumer market might be giving too many kudos to GM engineering.
 

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Yes it can. We measured a 10 bar drop in cylinder pressure by going main only at WOT conditions. The calibration of injection events are where it is at. We have past experience working with GM on some export projects. It seems they put some younger, inexperienced engineers on this platform and thus the refinement is not the best. The GM calibration changed completely in 2019 and looks like the folks in Torino, IT did the cal work on the newer models. This job was even worse and some of the OEM mapping looks like it was completed on an engine dyno and not even in a vehicle. The consumer market might be giving too many kudos to GM engineering.
So are you saying that if you have a 2019 you might be in more "danger" to your engine or at least poorer fuel economy and less power than previous years? Or am I reading too much into it? How about the new injectors from 2019 on? How does that play into it?
 

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Injector part number for 2016-2019 - 55594509
Injector part number for a 2019+ - 55504598

Yes, I didn't mess that up. The 2019 model year shows that both part numbers fit, so perhaps it was a mid-year change? The new injectors do look a bit different and like they wouldn't be a drop-in replacement without at least changing the high-pressure lines from the rail to the injectors. Would be curious to know what else changed or why the change was done.
 
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Injector part number for 2016-2019 - 55594509
Injector part number for a 2019+ - 55504598

Yes, I didn't mess that up. The 2019 model year shows that both part numbers fit, so perhaps it was a mid-year change? The new injectors do look a bit different and like they wouldn't be a drop-in replacement without at least changing the high-pressure lines from the rail to the injectors. Would be curious to know what else changed or why the change was done.
As you mentioned, the fitting for the feed line is different, the electrical connection appears to be the same. Wondering too if, assuming one can update the feed line, if the new injectors can run off the old ECM, and if they can, if it would be a good "bulletproofing" move to update to the new injectors. I doubt the Denso ECM would play (at least not without changing it's settings) with a different brand of injectors even if the physical electrical connection is the same. Perhaps someone who actually knows this stuff can weigh in.

On to what I can control and do, also wondering if diligently using a good lube/cleaning additive and adding a 2 micron Racor marine filter after the OEM box (the add on filter continues to work perfectly by the way, no affect on the filter life screen, nothing visible in it to date) will help to protect me from the dreaded stuck injector and holed piston nightmare. Those steps can't hurt I suppose.

Old injector:

407330



New injector:

407331
 

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So are you saying that if you have a 2019 you might be in more "danger" to your engine or at least poorer fuel economy and less power than previous years? Or am I reading too much into it? How about the new injectors from 2019 on? How does that play into it?
Stock is safe. I am referring to the mapping for timing, boost, mass air setpoint. There are many non-linearities and discontinuity throughout the normal operating range. This is more typical for genset engine calibration. It is just not optimized from a BSFC standpoint. Most likely, the bench calibration met emissions in the vehicle and not much more effort was resourced for drive ability characteristics.
 

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My truck has emissions testing coming up soon and I still had GM's recall cards on my desk, so I finally relented and took my truck in for the recall work. Not sure about my state, but my research suggested that some states will deny registration renewal (CA for sure) if the DMV sees emissions related recall work not completed. To be honest, I also wanted to be on record as completing the recall and purchasing the EPA compliant tune.

After driving home from the dealer with the GM settings, I simply could not bear to drive the truck with the stock settings. I had forgotten just how soggy, numb and awful the stock settings are. The engine didn't even sound as good as it did before, the cool little intake hum at cruise was gone. Clearly my 2.8 was not nearly as happy as it was before I brought it in to the GM dealer.

Purchased and installed GDE's EPA compliant tune ($50 for prior customers, I elected to get the regen notification screen for another $25) and to be honest, I can tell no difference between it and their prior "Pre EPA" tune that I had before. All the same solid, immediate and linear response to any touch of the pedal is back, the quantity of power is back, even the intake hum. I would never be able to definitively tell the difference between pre EPA and EPA compliant settings. If anything, the latest settings seem a bit smoother at low RPM pulling a light load in a tall gear, but that is seriously nit picking. Any differences there may be on the dyno are not readily apparent in actual use.

Transmission settings were much the same, I was running the "09AC" file before, the latest approved settings are slightly more refined, but nothing drastic, a tiny bit smoother but in no way "mushy". I can't imagine a 6L50 trans working any better than this, as GDE can't do anything about turning our 6 speeds into an 8 or 10 speed.

So I have used GDE's pre EPA settings for 40,000 miles, the latest GM settings for 15 miles, and now GDE's compliant settings, so I can say from immediate experience what the differences are. At this point I dunno why GM does not pay GDE a bunch of money and simply use their EPA approved settings, as they are night and day better than the settings GM sends these engines out into the world with.

In their prior post GDE said "most likely, the bench calibration met emissions in the vehicle and not much more effort was resourced for drive ability characteristics". That is a nice way of saying that the stock settings are raw and unfinished, and no refinement or "fun" of any kind was baked into them.

For those who feel they "missed out" on the pre EPA settings, take heart, you really are not missing out. As far as the driving experience goes, all the goodness of the pre EPA settings is still there. I am shocked - really did not expect the compliant settings to be this good and yet they are just as refined and just as much of a kick in the pants too. Kudos GDE, well done :cool:
 

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I really want a GDE tune, or maybe the HD Diesel Supply tune, but with my luck I'd end up with a stuck injector and wreck my engine. Probably going to wait until the engine warranty is up.
 
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@Duken4evr Not sure if you've noticed or knew, but pre-tune did you ever shift the transmission to L with Tow/Haul/EB enabled to prevent the aggressive automatic downshifts? I did this countless times when stock to avoid having it automatically downshift and rev up to 5,000 RPM because it thought that was necessary for more effect grade and exhaust braking. GDE's trans tune has enabled automatic downshifts in L mode, which is unfortunate. I reached out to them about this and they insist I'm mistaken, that the automatic downshifts happen in L mode as well and always have, even stock. Even the manual for 2017 states that automatic downshifts will not happen in L (Range Selection) mode. I've sent them my stock trans tune so they can look at it, but so far they are refusing to accept that I know how my truck operated when stock. ;) The automatic downshift in L with their trans tune was immediately noticeable last weekend since my sole purpose of using L downhill is to control when it downshifts. That control is now gone.

Hopefully they'll see what I'm talking about in the stock trans tune, I haven't recorded a video yet showing how it works when stock but I know multiple owners here know exactly what I'm talking about and can confirm what I and the diesel supplement from GM say is true.
 
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Why not just take it out of towhaul if you don’t want the grade braking
I think you misunderstand. I use the exhaust brake when going down long, non-freeway grades and to help maintain speed so I'm not constantly tapping the brakes. Exhaust brake + L mode worked wonderful for this because I could keep the RPMs around 2,500-3,000 and maintain speed without the engine screaming. Since the GDE trans tune has enabled automatic downshifting/grade braking while the transmission is in L mode this ability is gone.
 

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@Duken4evr Not sure if you've noticed or knew, but pre-tune did you ever shift the transmission to L with Tow/Haul/EB enabled to prevent the aggressive automatic downshifts? I did this countless times when stock to avoid having it automatically downshift and rev up to 5,000 RPM because it thought that was necessary for more effect grade and exhaust braking. GDE's trans tune has enabled automatic downshifts in L mode, which is unfortunate. I reached out to them about this and they insist I'm mistaken, that the automatic downshifts happen in L mode as well and always have, even stock. Even the manual for 2017 states that automatic downshifts will not happen in L (Range Selection) mode. I've sent them my stock trans tune so they can look at it, but so far they are refusing to accept that I know how my truck operated when stock. ;) The automatic downshift in L with their trans tune was immediately noticeable last weekend since my sole purpose of using L downhill is to control when it downshifts. That control is now gone.

Hopefully they'll see what I'm talking about in the stock trans tune, I haven't recorded a video yet showing how it works when stock but I know multiple owners here know exactly what I'm talking about and can confirm what I and the diesel supplement from GM say is true.
My recall is that grade braking is definitely disabled in "D" with GDE's trans tune. I believe it is also disabled in "L" but activating tow/haul in either D or L turns grade braking back on again, and it aggressively downshifts if you touch the brakes on a big downhill. I was running the 09AC trans tune. Have not been on the big hills with the EPA trans tune, which I like slightly better than 09 AC as it is ever so slightly smoother, and the 1st to 2nd shift is slightly better.

I like to "game" the system on big downhills by dropping it into "L" at the top of the hill, which downshifts it to 5th, then I upshift to 6th, and then hit the EB button, which puts it back to 5th again. Usually using the button to select the gear in "L" mode from that point forward generates enough engine braking, running up to 3K RPM creates what feels like a parachute. If I need to use the brakes to further control my speed, I turn off the EB first so the engine does not rev to the moon. This is the whole "procedure" I follow to get the transmission to do what I want it to do on the famous "Ike Gauntlet" and Vail Pass on I-70 :LOL:

Have not had trouble that I can recall with it grade braking and revving excessively in "L" with the EB off that I can recall. I have not been in any situations where I was doing my "procedure" on a downhill and had to urgently brake though. I probably thumb it up a gear just before initiating braking because I too have had the engine rev higher than I would like on big downhills. It is all muscle memory at this point, and I don't want my engine doing that again.

I would love to have grade braking turned off completely in all circumstances. No doubt it is fine with the free revving V6, but grade braking feels super clumsy with the 6 speed transmission's gappy gear spacing, and the narrow comfortable rev range diesel engine.
 

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My recall is that grade braking is definitely disabled in "D" with GDE's trans tune. I believe it is also disabled in "L" but activating tow/haul in either D or L turns grade braking back on again, and it aggressively downshifts if you touch the brakes on a big downhill.

I "game" the system on big downhills by dropping it into "L", which downshifts a gear, then I upshift to 6th, and then hit the EB button, which puts it back to 5th again. Usually using the button in "L" mode generates enough engine braking, 3K RPM is quite a parachute. If I need to use the brakes to control my speed, I turn off the EB first so the engine does not rev to the moon.

This is the whole "procedure" I follow on the famous "Ike Gauntlet" and Vail Pass on I-70
Yeah, that dance is something I never had to do when stock. EB on, shift to L, set the highest gear, and head down the grade. It would hold the highest gear selected in L with no aggressive downshifting no matter how many times I hit the brakes. If it were in D with the EB enabled then it would downshift as much as possible when going downhill or even coming off the freeway to a stop. I used L for the sole purpose of stopping that stupid downshifting when using the exhaust brake.

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For the emissions compliant tunes such as from GDE, that bump the power up by a significant margin plus reduce the EGR usage; if such an improvement was possible, why didn't Chevy/GM do this from the factory? There must be a logical reason and corresponding trade-off. Was Chevy just being sure they pass emissions by a fat margin? Or maybe the power was turned down so the user could pretty well run it at 100% without worry of breaking any hard parts? Does the new tune increase EGT possibly shortening the life of the emissions parts (DPF, SCR)?

Everything in life has trade-offs, I'm just trying to understand this one to help me make a decision on buying the tune when my warranty is up. Truth be told, I would personally prefer a reduced-EGR tune that kept the stock power numbers, though I do understand that might not sell as well to the general public as a power boosting tune.
This may not be your ticket.. It woke up my 2021 ZR2 Diesel though !! Literally unplug your peddle and add this...POW ! Has Eco settings too.. simply changes the throttle signal.
 
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