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Cracked Piston

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Cracked piston along the con-rod
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Still trying to confirm correct Rod bearings. Local dealer was useless. There is a G on the Rod and the bearings have a green color to them so I’m thinking they are Green. Options are Blue Green or Red.
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terryjm1
Cutterman said:
They direct ship from Exergy.
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I suppose after spending $$$$ to rebuild an engine, $1600 for injectors doesn’t feel too bad.
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Total cost with the new injectors will be around 4k.
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SFLTruck
Cutterman said:
Total cost with the new injectors will be around 4k.
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Is that with pistons, injectors, gaskets and so on?
Have you got it apart enough to determine if the cylinder wall got damaged?
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Cutterman said:
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.
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I reached out directly to Exergy, their stock injectors are 100% stock. They've made no changes or improvements to them over the OEMs that you can get from GM/Denso.
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DieselDrax said:
I had to do the same, basically any slight hill/incline between 45-55MPH lugged the engine and caused excessive vibrations so I'd have to shift to L and make sure to run at higher RPMs.

Haven't had to do that since going back to the stock engine tune with the GDE trans tune...
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Interesting ...mine does that too but I never suspected that my GDE tune might have anything to do with it . I did bring it up with them and they blamed the weak torque converter on these trucks . I live in Texas so don't have do deal with this issue much, fortunately. but it would drive me nuts if I lived in the hills.

Apart from that , it's better than stock in every way imaginable .
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tex2018 said:
Interesting ...mine does that too but I never suspected that my GDE tune might have anything to do with it . I did bring it up with them and they blamed the weak torque converter on these trucks . I live in Texas so don't have do deal with this issue much, fortunately. but it would drive me nuts if I lived in the hills.
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My biggest complaint about GDE is they think their $#1+ doesn't stink and nothing is their fault. It makes it impossible to get them to consider fixing anything, and even if they were to admit they could do something better they won't because any changes to the emissions-compliant tune will cost them $12,000 to have it re-certified as EPA-compliant. Their arrogance gets in the way of making a better product. Very Apple-like in that regard.

I know a lot of people have been happy with their GDE tune so my goal isn't to get people to not buy their tunes, I just want people to be aware that their experience may be less than perfect and to consider that before shelling out the money.
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I wanted to follow up on this thread in regard to my posts about GDE, I suspect they saw my posts here as they reached out the other day here and via email wanting to spend some time trying to diagnose my complaints/issues. They've been very responsive and we've been having a good dialog, it's after I went to reproduce my issues with their tunes that things got weird. As part of going back to the stock engine tune I installed a Hypertech inline speedo calibration module due to my tire size. So today I installed the GDE tune that was configured for stock tire sizes as I didn't want to take the time to remove the Hypertech module and then took the truck for a drive. It's running completely different with the stock tire tune compared to the tune that had been adjusted for my tires. It now runs with OEM-quality refinement with a nice boost in throttle response and power/torque. The excessive vibrations are completely gone and it honestly feels as good as OEM in terms of refinement. I'm likely going to keep these tunes installed as I no longer feel like I'm hammering the engine to death. Try as I might, even letting the trans upshift so the engine was running at 1,250RPM at part throttle didn't produce anything weird or make me feel like I needed to manually downshift. I rolled into the throttle all the way to the point that it downshifted on its own and it was totally smooth.

I've relayed all of this (and more) to GDE and am waiting to see what they have to say, I can't help but think something got messed up with the tire-size-adjusted tune(s) that didn't happen to the stock-tire-size tune. I never ran the stock-tire-size tune before today.

@tex2018 is your tune configured for stock tire size or are you running a GDE tune that compensates for non-stock tire size? Trying to see if there's any commonality between our excessive vibration conditions.
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DieselDrax said:
I wanted to follow up on this thread in regard to my posts about GDE, I suspect they saw my posts here as they reached out the other day here and via email wanting to spend some time trying to diagnose my complaints/issues. They've been very responsive and we've been having a good dialog, it's after I went to reproduce my issues with their tunes that things got weird. As part of going back to the stock engine tune I installed a Hypertech inline speedo calibration module due to my tire size. So today I installed the GDE tune that was configured for stock tire sizes as I didn't want to take the time to remove the Hypertech module and then took the truck for a drive. It's running completely different with the stock tire tune compared to the tune that had been adjusted for my tires. It now runs with OEM-quality refinement with a nice boost in throttle response and power/torque. The excessive vibrations are completely gone and it honestly feels as good as OEM in terms of refinement. I'm likely going to keep these tunes installed as I no longer feel like I'm hammering the engine to death. Try as I might, even letting the trans upshift so the engine was running at 1,250RPM at part throttle didn't produce anything weird or make me feel like I needed to manually downshift. I rolled into the throttle all the way to the point that it downshifted on its own and it was totally smooth.

I've relayed all of this (and more) to GDE and am waiting to see what they have to say, I can't help but think something got messed up with the tire-size-adjusted tune(s) that didn't happen to the stock-tire-size tune. I never ran the stock-tire-size tune before today.

@tex2018 is your tune configured for stock tire size or are you running a GDE tune that compensates for non-stock tire size? Trying to see if there's any commonality between our excessive vibration conditions.
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Well, my ECU tune is configured for stock tire size - 255 / 65 / R17 (like yours, I assume).

My latest TCU tune is configured for an updated tire size (but as I understand , the TCU tune is not really affected by tire size) .

I don't want to upgrade to the latest ECU tune for reasons that will remain unspoken of.

It may be possible that we have experienced the same symptoms.

Good news though is that I've just got a RC speedo calibrator (as I've very recently upsized from 265 / 65 / R17 to 265 / 70 / R17) that I will be installing in the next few days .. and essentially replicating your configuration. Will report back with results .


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tex2018 said:
Well, my ECU tune is configured for stock tire size - 255 / 65 / R17 (like yours, I assume).

My latest TCU tune is configured for an updated tire size (but as I understand , the TCU tune is not really affected by tire size).

I don't want to upgrade to the latest ECU tune for reasons that will remain unspoken.

It may be possible that we have experienced the same symptoms.

Good news though is that I've just got a RC speedo calibrator (as I've very recently upsized from 265 / 65 / R17 to 265 / 70 / R17) that I will be installing in the next few days .. and essentially replicating your configuration. Will report back with results .


View attachment 9707
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Nice looking truck!

I was hoping maybe you were running an engine tune programmed for a non-factory tire size as that would at least be something common with our symptoms. I was running 275/55R20 when I ordered the tune and have since gone to 265/70R17 tires on ZR2 wheels. Effectively the same diameter/circumference as I didn't have to make any adjustments to the inline calibration module, speedo and GPS still match.

At this point I don't want to mess with a good thing if I don't have to and will keep the current GDE tunes in place. It'll be interesting to see if GDE finds anything majorly different between the 2 engine tune files they gave me.

This is my current setup...

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Duken4evr
Interesting! In the old days engines used to run a bit poorly and we would wait for them to "clean out". Now when they run a bit poorly it means it needs immediate attention :LOL:
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terryjm1
I just completed my first long distance drive towing a trailer since installing the tune. I went 1100 miles pulling what I estimate to be 3500-4000 pounds (uhaul 6x12 enclosed with a full load inside). No complaints at all with how it performed. i forgot to record the mpg but believe it was right at 18mpg. Most of it was at 65 mpg with the last 200ish miles at 45 to 60 mph. I did run into a lot of head and side winds for at least half of that as well as an overall 7500 feet elevation gain with a lot of of up and down hills. On the way there (no trailer) I reached a new high “last 450 miles” of 36.6 mpg. And that was about half at 60-65 mph and half 70-75 mph. But, again, there was a decrease in elevation overall of about 7500 feet. This is all with the intact tune. I run stock tires, still have the air dam, and have a 2 inch Autospring lift.

Again, the the only thing I don’t like about the tune is I think (I am not an automotive engineer) it should stay in a lower gear longer at 45-55 so the rpms stay a little higher. I live where 55 mph is 90% of my driving and it is on mountain highways. For the first 12 miles of every trip it is uphill. It may not be needed but I switch to tow/haul when I take that drive (if I remember) and that makes the engine rev a little higher and makes me feel better although I am unsure it really matters.
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DieselDrax said:
I wanted to follow up on this thread in regard to my posts about GDE, I suspect they saw my posts here as they reached out the other day here and via email wanting to spend some time trying to diagnose my complaints/issues. They've been very responsive and we've been having a good dialog, it's after I went to reproduce my issues with their tunes that things got weird. As part of going back to the stock engine tune I installed a Hypertech inline speedo calibration module due to my tire size. So today I installed the GDE tune that was configured for stock tire sizes as I didn't want to take the time to remove the Hypertech module and then took the truck for a drive. It's running completely different with the stock tire tune compared to the tune that had been adjusted for my tires. It now runs with OEM-quality refinement with a nice boost in throttle response and power/torque. The excessive vibrations are completely gone and it honestly feels as good as OEM in terms of refinement. I'm likely going to keep these tunes installed as I no longer feel like I'm hammering the engine to death. Try as I might, even letting the trans upshift so the engine was running at 1,250RPM at part throttle didn't produce anything weird or make me feel like I needed to manually downshift. I rolled into the throttle all the way to the point that it downshifted on its own and it was totally smooth.

I've relayed all of this (and more) to GDE and am waiting to see what they have to say, I can't help but think something got messed up with the tire-size-adjusted tune(s) that didn't happen to the stock-tire-size tune. I never ran the stock-tire-size tune before today.

@tex2018 is your tune configured for stock tire size or are you running a GDE tune that compensates for non-stock tire size? Trying to see if there's any commonality between our excessive vibration conditions.
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I am glad to hear this because I respect your opinion and I was bewildered why my GDE experience was so different from yours. I don't find the lugging an issue when truck is solo and if it were I'd just use manual and ensure rpms stayed above 1500 if there were any load. When I tow, I typically put it in manual tow mode and there is no issue at all with lugging. I'm super happy with the tune but, of course, the long term reliability and effects on the engine remain to be seen.
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terryjm1
DieselDrax said:
I reached out directly to Exergy, their stock injectors are 100% stock. They've made no changes or improvements to them over the OEMs that you can get from GM/Denso.
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I still think I will do a preventive injector change at 100,000 miles. Injectors, even ones that don’t have the concerns associated with ours, wear out. Waste of money? Maybe a little at 100,000 miles, but…
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Duken4evr
terryjm1 said:
I still think I will do a preventive injector change at 100,000 miles. Injectors, even ones that don’t have the concerns associated with ours, wear out. Waste of money? Maybe a little at 100,000 miles, but…
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If not for the darn #4 injector access hassle this would be an easy do it at home job as far as physically getting the injectors installed. The cowl can be removed, but it it is glued in there good and getting it off is reportedly a major PITA. Evidently each injector has a unique code; this has to be entered into the ECU also. There is more to swapping injectors than just slapping them in there it seems.
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terryjm1
Duken4evr said:
If not for the darn #4 injector access hassle this would be an easy do it at home job as far as physically getting the injectors installed. The cowl can be removed, but it it is glued in there good and getting it off is reportedly a major PITA. Evidently each injector has a unique code; this has to be entered into the ECU also. There is more to swapping injectors than just slapping them in there it seems.
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I know the #4 injector is going to be a real issue. I haven’t even really looked at it yet. I wonder if an access hole could be made? With coding, I also wonder if that has to be done by the dealer?

I did ask the folks at GDE if the factory tune had to be installed to code the injectors and they said it doesn’t have to have the factory tune to code the injectors. That was via email so I didn’t get a chance to expand on the question.
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Duken4evr
Interesting idea about making an access hole. I have a Sawzall and am not afraid to use it. Maybe I should be :LOL:
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terryjm1
Duken4evr said:
Interesting idea about making an access hole. I have a Sawzall and am not afraid to use it. Maybe I should be :LOL:
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I was thinking maybe a round hole that a plug could be installed. Again, I haven’t even looked to assess it. Frankly, it seems like something GM should have planned for injector replacement. Prying off a glued on panel is hardly a plan.
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All four rod bearing upper half’s look like this. More wear than I would like with only 60k on truck.
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Makes me wonder if the cracked piston and that wear are due to a lubrication problem. Any signs of sludge in the oil pan or blockages forming in the piston cooling jets or crankshaft oil passage openings? Based on what I've seen with failed EcoDiesel engines that were running the initial ACEA C3 5w30 oil spec (same oil spec our engine calls for) it makes me wonder if something similar is happening to some of the 2.8s. I know there's speculation that the holes in pistons are being caused by broken injector tips, but your piston does not look like it was damaged by a cracked or stuck injector. It looks like it cracked due to high temps and/or increased friction due to insufficient lubrication. Some EcoDiesels showed carbon/polymer blockages in the crankshaft that was blocking oil flow which lead to spun bearings.

Had you ever done UOA on your truck?
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