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The ECU is what actually commands the TCM to the selected gear.
Huh?

The trans tune is what determines the shift points based on various parameters, the ECM doesn't tell the TCM when to shift. If it did then the trans tunes would be pointless. GDE even states this.

Transmission flash information

  • Improved usage of torque converter lock-up
  • Optimized shift points in normal “D” for part throttle fuel economy, WOT performance, and responsiveness
  • Tow/haul shift strategy optimized for operation in peak torque band engine speed range and better engine braking performance
 
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Cracked pistons seem to be less common than hole burned through pistons, but both can be caused by injector issues. Have them checked and make sure the injectors are OK during the repairs because you certainly don't want that to happen again.

My experience with the GDE tune (pre and post compliant) is that the engine runs turbine baby's butt smooth vs. the somewhat "agricultural" OEM settings. I love the earlier and firmer shifts that trans tune provides, but also don't like loading the engine below 1.5K RPM. If traffic dictages going 50 to 55 MPH or so, I drop it into manual mode and 5th gear. The one thing I would change with the trans tune is to not have it shift so early into 6th gear.

One thing that really affects engine smoothness is the fuel's cetane level. I buy nothing but high volume but bargain basement and I presume low cetane fuel. I figure it is fresh and I can treat it to make it work well. I dose it with 5 ounces of Optilube "Summer +" with each fillup which is generally around 19.5 gallons and over double the "premium" dose rate. Cold starts are much smoother as is general running with the cetane boosted fuel. It definitely runs a lot more "diesely," particularly during cold starting, if the fuel is not treated or minimally treated.

America's diesel fuel generally sucks ass - the exception I have found is Sinclair, that stuff is quite good. Alas Sinclair stations are not near me, and my attached to Kroger grocery "fuel points" driven station, which has diesel at the end of each of it's 12 aisles, is a lot cheaper and busier than the other stations, so that is where I go.
 
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I bought all new GM pistons which are Mahl now and new injectors (Exergy stock) as they supposedly corrected the injector issue as I don’t care to do this again.
Would like to hear more about Exergy fixing the injector issue, either details or something official that says how they are different than stock Denso injectors. I hope I don't have to deal with a failed injector, but at the same time replacing the injectors with updated ones could end up saving money. Just a hard pill to swallow for something that may never happen to me.
 
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“Would like to hear more about Exergy fixing the injector issue,”

Me too! I have been strongly considering replacing my injectors as a preventive measure. Even if they don’t fail because of a defect, they will wear out.

Also, while I am not expert, I believe most of the engine failures are injector related. I haven’t seen reports of engine failures for trucks built after they changed injectors to the new type.
 

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“Would like to hear more about Exergy fixing the injector issue,”

Me too! I have been strongly considering replacing my injectors as a preventive measure. Even if they don’t fail because of a defect, they will wear out.

Also, while I am not expert, I believe most of the engine failures are injector related. I haven’t seen reports of engine failures for trucks built after they changed injectors to the new type.
But the problem is, unless I'm mistaken, is you have to change the head as the new injectors mount differently they're not a drop in replacement.
 

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But the problem is, unless I'm mistaken, is you have to change the head as the new injectors mount differently they're not a drop in replacement.
Correct, but if Exergy has been able to make the first-gen injectors "bulletproof" then that becomes a non-issue. They're just saying there haven't been any known failures since the injector change in 2019/2020. Apparently the pistons were also upgraded/improved, if that's the case then there's not really any way to know if the lack of failures was due to the injectors or pistons.
 

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Cutterman’s is a 2016. So, if the injectors he is installing have been improved, they are for the 2016 head.

Would too much fuel cause a cracked piston?

The only experience I have with broken pistons (ring beds) was decades ago and it was due to running too low octane after I built an engine with very high compression. I was 17 yo… tough and expensive lesson.
 

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Huh?

The trans tune is what determines the shift points based on various parameters, the ECM doesn't tell the TCM when to shift. If it did then the trans tunes would be pointless. GDE even states this.
If I watch my iDash I can see where the trans gets "commanded" (their wording) to a particular gear and then there is a field for "Actual gear". There is about 1/16 to 1/8 second between commanded and when "Actual" happens, obviously you can confirm the actual by the seat of your pants shift.

There is a rhythm between actual engine loading % and throttle pedal % seen on the iDash before a shift actually gets "commanded" and actually happens. Same goes for a down shift and IMO I liken this to kick down linkage from the old days. I may be wrong but IMO the ECM is the ultimate decision maker, it seems it Commands the Gear and the TCM does the actual work of changing to the respective gear requested and reports back (Actual Gear) when the work is actually accomplished.


Correct, but if Exergy has been able to make the first-gen injectors "bulletproof" then that becomes a non-issue. They're just saying there haven't been any known failures since the injector change in 2019/2020. Apparently the pistons were also upgraded/improved, if that's the case then there's not really any way to know if the lack of failures was due to the injectors or pistons.
So here is the big question if Energy can supply a better injector then at what mileage do you think we take the plunge?
 

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“So here is the big question if Energy can supply a better injector then at what mileage do you think we take the plunge?”

I am at 76,000 now. I was thinking 100,000 would be good time to change them. But… seems failures are more common at lower mileage than that.
 

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If I watch my iDash I can see where the trans gets "commanded" (their wording) to a particular gear and then there is a field for "Actual gear". There is about 1/16 to 1/8 second between commanded and when "Actual" happens, obviously you can confirm the actual by the seat of your pants shift.

There is a rhythm between actual engine loading % and throttle pedal % seen on the iDash before a shift actually gets "commanded" and actually happens. Same goes for a down shift and IMO I liken this to kick down linkage from the old days. I may be wrong but IMO the ECM is the ultimate decision maker, it seems it Commands the Gear and the TCM does the actual work of changing to the respective gear requested and reports back (Actual Gear) when the work is actually accomplished.
You're confusing what is doing the commanding and what is "saying" actual. The TCM is commanding the transmission to shift and "actual" is coming from the transmission so that the TCM knows what gear it's actually in, if it did what it was told, etc. The ECM isn't commanding the TCM to shift. The TCM is external to the transmission and anything related to transmission shifting and shift points comes from the TCM, not ECM. The TCM will monitor things like APPS and engine load to shift based on programmed shift points, but the ECM doesn't command the TCM to tell the trans to shift. If the TCM commanded the transmission to shift and it didn't then it would trigger a DTC.

Similarly, if you were to try and shift into too low of a gear for the speed you're going you'd see a "shift denied" (or similar) message as the TCM won't allow the transmission to downshift if it would cause an engine overrev.

For our trucks, the ECM and TCM are part of the same PCM part (mounted to the passenger firewall under the hood) rather than physically separate modules.

So here is the big question if Energy can supply a better injector then at what mileage do you think we take the plunge?
I mean, if you're going to take the plunge then I would say the sooner the better. There's no way to know when an injector may fail. I'm not even sure monitoring balance rates would help here, I haven't heard one way or the other if anyone has seen the balance rate for a failed injector go wild before the damaging the engine.
 
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