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Discussion Starter · #1 ·
Just curious if I am the only one on here with AFM still active. :shock: If still active have you experienced any issues? Details?
2011 5.3 LC9
Here is mine so far: 95K miles. Never had a misfire. Still have original plugs wires etc. Still clean. Never had any engine issues or stored a trouble code.
Problems so far related to AFM: Slight oil consumption a while back through crankcase vent. I posted the fix for mine a while back. No problems since.

Unrelated... Vibration issue.. tires.

Oil
OCI-5k
Castrol GTX Magnatec
MMO
AC Delco PF63e
 

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My old truck (2008) made it 75000mi until i owned it and disabled it. The truck had no problems that were related to the AFM, I just disabled it for piece of mind. Disabled it on my current truck (2017) for the same reason. Just don't feel like having possible problems in the future.
 

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LOL the engineering background experience shows in a thread again. And it always works flawlessly until it fails.

OP- Judging by the amount of your AFM posts, you seem pretty worried about it, maybe youre one of the lucky ones that never has an issue and never will. My 08 started to tick when bought it with 50k on it. I turned AFM off and was never ticked after that 60k later. Roll of the dice. I personally rather be safe than sorry, especially since AFM has zero effect on real world MPG.
 

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GR2017 said:
I have no intention of ever disabling the AFM on my 2017 WT V6. It works flawlessly. I have an engineering background so I am not taken in by internet silliness.
LoL

Thanks, I needed a chuckle to start my day. I have friends who are engineers, that also happen to work for GM (I live in metro Detroit). They might disagree with your statement.
 

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Mine was off n my 08 GMC but was still having the oil consumption issues. I reset all back to stock and took it in to the dealer and they did the service tag stuff on it. I would have to check if i ever turned it back off after that or not but so far oil issues are gone and my truck does not get babied. That was at about 80K and it has 110K on it now. As to the gas mileage it does not seem to change that much with it on or off but i think it was slightly better with it off. I need to check and see how i have it set again i guess.
 

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GR2017 said:
I have no intention of ever disabling the AFM on my 2017 WT V6. It works flawlessly. I have an engineering background so I am not taken in by internet silliness.
 

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Funny how thousands of trucks have the same issues with AFM since it is only internet silliness. As an engineer you should understand that no matter what you do. You can not make up for a rotating assembly that is not firing. Dead cylinders are inefficient. Without all of the steps of a running engine your oiling systems will not operate properly. GM even has gone as far as to have Tech Service Bulletin #10-06-01-008G: to address issues along with valve cover redesign and an AFM oil deflector. It's not even just GM that has had issues with cylinder deactivation. Every manufacturer who has tried it has issues. Chrysler-Dodge have issues with MDS, Mercedes stopped using ACC because of issues. Honda settled a class action lawsuit over oil burning issues on their VCM system. Maybe you'll be one of the lucky ones. Does not mean that AFM is not a fundamentally flawed system.
 

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The only one I've owned that I did not disable AFM, gave me problems, 08' Z71 Avalanche. At 90k went in to dealer for loud tick that just showed up out of nowhere. Warranty covered it, but they had to replace, cam, lifters, oil pump, etc. Was told by the mechanic that it was AFM that caused issue, and suggested that I disable it. Said they had fixed many with the same issues, that I was lucky that mine was still under warranty. From then on, no AFM for me on any more of my trucks. Not going to take the chance, and have not had any more issues.
 

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Road Transport Engineer = Truck driver
Sanitation Engineer = Garbage man
Mechanical Engineer = actual engineer
 

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Discussion Starter · #19 ·
ferraiolo1 said:
LOL the engineering background experience shows in a thread again. And it always works flawlessly until it fails.

OP- Judging by the amount of your AFM posts, you seem pretty worried about it, maybe youre one of the lucky ones that never has an issue and never will. My 08 started to tick when bought it with 50k on it. I turned AFM off and was never ticked after that 60k later. Roll of the dice. I personally rather be safe than sorry, especially since AFM has zero effect on real world MPG.
I'm somewhat concerned. But so far my own evidence seem to prove my theories. Although there is always the possibility other issues, maybe with the lifters. The problem I see getting info is that that there isn't a lot out there. Most just turn it off as you did with doing any counter measures other than just turning off the AFM. Most of these issue also don't just go away even turning off AFM. Seems more of a guessing game than finding what the actual problem is with the system. That's completely understandable but at the same time is exactly what it is. No data no info just popular concept.

Another idea that everyone seems to have is that cylinder deactivation is just impossible to achieve. Its really not and not that complicated. It almost seems that some of this is either intentional or just blatantly overlooked. GM could correct this but just don't care to or do not want to. The key also could be in oil. Even though no one wants to believe or admit this with the high OCI synthetics revolution and popular concepts. Some things are always better on paper until proven otherwise in the field. And some still may be unwilling to see the issues then. I don't think deactivation is the answer and really sidestepping the problem but that's what I have and I feel like it can be properly maintained to work without catastrophic failure. Maybe not. Time will tell. It is interesting even for everyone on the AFM deactivate side.

Some suggestions elude to my engine just being a lucky one. But I did start to see consumption. Some of the issues did start showing there head, but I have done something about the issue, not just turning it off. If I had only turned off AFM Id probably be right there with the majority. I have seen it where someone's engine continues to loose oil etc even with the AFM off because the affected parts or issues were not corrected. In truth in most cases the user doesn't really know what the issue was. If things get any better its just said that its better because AFM is off. Maybe it is maybe it isn't. I don't feel anything is going to flip a switch turning it off unless more is done at the same time.
 

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I think the lifter issue is one of the bigger concerns. They can fail and take out the cam with them. Sometimes they just fall apart and others just fail to lock or unlock. It's a crap shoot. Did I blindly turn it off ? I just made a decision based on the information I gathered from actual people posting their actual nightmares from AFM failures. My truck had none of the symptoms and I turned AFM off in the hopes of preventing problems in the future. I'm not telling anyone else to do it but I am strongly suggesting it.
 
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