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Posted
2 hours ago, dgstarr63 said:

I copied this from the 2020 Silverado Service Manual.  I is not entirely clear what they mean by "low gear ranges".

 

I read that to mean the Low Gear ranges in the 2-speed transfer case. 4-low, for example.

 

Posted (edited)
On 7/24/2021 at 7:20 PM, M1ck3y said:

 

Wtf is tip in bump acceleration, and oil aeration mode. Anyone who knows next to nothing about engines and oil, knows you don't want oil aeration, EVER. Did you write that?

 

Cylinder deactivation has been around for ever and no one has heard of failing lifters? It doesn't matter what generation its in. Lifters that are designed to collapse and stop doing their intended job will always fail. Why? Because your asking the part to do something it really shouldn't be doing (unless you've tuned it out)

 

But its ok. Soon GM will stop having to design engines (if they haven't already). Vehicle Development cost's will drop dramatically, the number of humans needed to make the vehicles will drop dramatically, Material cost for vehicles will rise slightly. They'll charge way more money, the people will pay way more money, no more cylinder deactivation, everyone's happy.

 

Until people realize batteries suck. The used ICE vehicle market will sky rocket. Gasoline will skyrocket. But everyone's happy because they have an ice powered vehicle. Until lifters start failing because of cylinder deactivation... 

 

But its ok because gasoline will no longer be affordable for most people. And electric vehicles wont be afforable for most people. Anyone see where this is going?

I believe either Melling automotive group did a nice explanation of the issue on lifter collapse. it would help extend the lifter life by increasing the activation speed to around 55-60 mph instead of the stock software over cycling the system in stop and go traffic.  who needs v4 at 25-30 mph when your coming up on a red light 

Edited by pokismoki
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Posted
On 7/24/2021 at 9:20 PM, M1ck3y said:

 

Wtf is tip in bump acceleration, and oil aeration mode. Anyone who knows next to nothing about engines and oil, knows you don't want oil aeration, EVER. Did you write that?

 

Cylinder deactivation has been around for ever and no one has heard of failing lifters? It doesn't matter what generation its in. Lifters that are designed to collapse and stop doing their intended job will always fail. Why? Because your asking the part to do something it really shouldn't be doing (unless you've tuned it out)

 

 

 

I would expect tip in bump acceleration mode to mean the ECU TPS response when in cruise control to a bump in the road that alters speed. Just a guess. Oil aeration mode is a set of conditions the ECU sees as likely to foam the oil. Also a guess. 

 

That particular lifter IS designed to collapse. So it IS doing something it should. 

 

Anybody remember hydraulic flat tappet lifters? How about Rhoads Lifters? Automatic lift/duration compensation and around for decades. When did they fail? Oil aeration and exceeding the bleed down rate by over speeding. Beat the retainers right out of them. ANY device will fail when not in the mode it was designed to operate under. 

 

That does not excuse GM from general poor design or manufacturing failures but the owner/operator has a hand in this pie too. Clean oil is one. 

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Posted
On 7/22/2021 at 2:45 PM, dgstarr63 said:

These issues are most likely due to computer issues which get the timing off on when to collapse and re energize the lifters. 

 

So it does every other function with computer like perfection EXCEPT the timing of the switching? Everything else is flawless? Yea.....we timing and fueling down to the hair on a gnat's but-t but can't time a DFM/AFM/DOD. Sorry...not buying that. 

 

What I am buying the the Melling explanation. Dirty oil, aerated oil. Leaking VLOM's...and yes a good old round of junk parts that made it into the final assembly. Still a fraction of production. A fraction of a fraction.  

Posted
1 hour ago, Grumpy Bear said:

 

I would expect tip in bump acceleration mode to mean the ECU TPS response when in cruise control to a bump in the road that alters speed. Just a guess. Oil aeration mode is a set of conditions the ECU sees as likely to foam the oil. Also a guess. 

 

That particular lifter IS designed to collapse. So it IS doing something it should. 

 

Anybody remember hydraulic flat tappet lifters? How about Rhoads Lifters? Automatic lift/duration compensation and around for decades. When did they fail? Oil aeration and exceeding the bleed down rate by over speeding. Beat the retainers right out of them. ANY device will fail when not in the mode it was designed to operate under. 

 

That does not excuse GM from general poor design or manufacturing failures but the owner/operator has a hand in this pie too. Clean oil is one. 

 

Yeah, they are designed to collapse. But in my mind it's just over complicating things and opening it up to failure. Just too many parts, too many points of potential failure... It's gotta be under an enormous amount of stress when it re-activates the lifter?

 

I went a bit overboard with my earlier post 🙄

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Posted
3 hours ago, M1ck3y said:

 

Yeah, they are designed to collapse. But in my mind it's just over complicating things and opening it up to failure. Just too many parts, too many points of potential failure... It's gotta be under an enormous amount of stress when it re-activates the lifter?

 

I went a bit overboard with my earlier post 🙄

 

All good. It IS complicated and simple IS better. But complicated can work and work well. 

 

I have this 'thing' for 40's and 50's Brit singles. Big one lung British motorcycles. Up to a few years ago Royal Enfield still made the Bullet 350 and 500 cc types. Awesome machines that put smiles on faces just starting them. Thing is you can't treat them like a 2020 Honda. Stone axe simple machines anyone can work on. To an Enfield lover the Honda is 'overly complicated' and yet it IS one of the most reliable machines ever to be built. They will both have their followers just like Ford VS Chevy. :P They just need to be treated for what they are. Simple. Right? 

  • Like 1
Posted
On 7/18/2021 at 4:32 PM, Mandalorian said:

 

I don't know where you're getting your legal advice, but as a former Alabamian I can tell you there absolutely ARE Lemon Laws in Alabama as there are in all 50 states. 

I have always been taught this but glad you mentioned that. Sure enough, there is. Thanks! 

Posted (edited)

Has anyone got their truck fixed after having this problem?  Did the fix hold or was it back in the shop again?  My truck has been waiting for parts for two weeks now. 

Edited by msween313
Posted

So just to confirm, these lifters won’t fail if we disable DFM? And the only way to do that is via aftermarket tuners? 

Posted
4 hours ago, msween313 said:

Has anyone got their truck fixed after having this problem?  Did the fix hold or was it back in the shop again?  My truck has been waiting for parts for two weeks now. 

Mine is sitting at the dealer still for "back ordered" parts. Isn't awesome owning a 50k dollar paperweight.

  • Like 1
Posted (edited)

All I can say ....  there's federal lemon laws too. 

 

Use them.  GM needs to feel it in the wallet so they resume quality over max profit.

Edited by steve841
Posted (edited)

 

 

Good explanation on what's happening with these bent pushrods.

 

I guarantee GM deleted the AFM/DFM due to this and not because of a "chip shortage." 

Edited by 20Denali21
Posted

 

Or could it be........

 

Listen carefully to the 'cause' of mistiming

ALL of them

Listen carefully to the required repair parts

Especially the ALL word

And cleaning routine

How many fail AGAIN due to poor or incomplete repair

How many to under or over full

AERATION, STARVATION and VARNSIH/SLUDGE

 

 

 

Posted

While some fail due to bad parts I believe OCI's are a big factor. I know this. My 12's motor is quieter than when I bought it used. A few short OCI's and then 3 K miles OCI's. At first the oil would get dirty quick. 

My guess the pervious owner did OCI's by the OLM. I cleaned it out IMO.

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