My 2019 Tahoe developed an odd rattling noise from the engine bay. The issue was diagnosed as the engine making this noise when switching from 4 to 8 cylinders. I would hate to bypass what the vehicle is designed to do. Can the computer be reset so the AFM works properly??
IS AFM DISABLEMENT NECESSARY??
- Thread starter BigBee44
- Start date
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Marky Dissod
Full Access Member
To answer the title: technically, no, it is not NECESSARY.
(Although core / trunk exercises are not strictly necessary, my lower back regrets that line of thinking.)
There is no Engine Control Module 'reset' that can fix the mechanical problem you described.
To address the noise that your engine makes, requires physical / mechanical solutions.
The only way to do anything with your ECM to stop the mechanical noise your engine makes when half of it wants to take a break,
is to disable V4 mode in the pcm.
You ought to consider the possibility that there are good reasons why this forum has no negative reviews regarding competent engine / transmission tuning.
However, since you "would hate to bypass what the vehicle is designed to do"
maybe you would prefer pouring some Marvel Mystery Oil, or some other potential 'liquid solution' to your problem?
The mechanical solutions that would require changing parts will definitely cost more, and you will still be stuck with a bug that you think is a feature.
At least figure out how much money V4 mode saves you a week, and stash that away for when it fails,
or when it takes out your transmission.
(Although core / trunk exercises are not strictly necessary, my lower back regrets that line of thinking.)
There is no Engine Control Module 'reset' that can fix the mechanical problem you described.
To address the noise that your engine makes, requires physical / mechanical solutions.
The only way to do anything with your ECM to stop the mechanical noise your engine makes when half of it wants to take a break,
is to disable V4 mode in the pcm.
You ought to consider the possibility that there are good reasons why this forum has no negative reviews regarding competent engine / transmission tuning.
However, since you "would hate to bypass what the vehicle is designed to do"
maybe you would prefer pouring some Marvel Mystery Oil, or some other potential 'liquid solution' to your problem?
The mechanical solutions that would require changing parts will definitely cost more, and you will still be stuck with a bug that you think is a feature.
At least figure out how much money V4 mode saves you a week, and stash that away for when it fails,
or when it takes out your transmission.
Is it currently stock? If so, then any computer changes would make it run in V8 all the time.......much like most everyone here agrees with. They system you speak of is prone to issues with the lifters that fail on the V4 mode. Dirty oil seems to be the biggest culprit for failure. Keep it at 5k or less with a good filter and 5w-30 oil.......get rid of the 0w-20 garbage.
I thank you for your timely response to my issue. The information you provided is valuable to me and greatly appreciated. One more thing this was my first post in this forum and your obvious sarcasm was spot on. I laughed and re-read it several times.....
Thank you for the information. I will make sure that the oil changes continue to be timely with the proper oil.
Thanks again!!
Marky Dissod
Full Access Member
I don't think I'll ever be funny enough, but I'm funnier than what happens when V4 mode fails,
or when the TCC fails and takes out the transmission with it.
or when the TCC fails and takes out the transmission with it.
2015TahoePPV
Full Access Member
here's another vote for get rid of the AFM system, speaking from experience
i bought the afm disabler that plugs in the diagnostic port... way nicer to drive, negligible difference in fuel mileage ..
2015TahoePPV
Full Access Member
Its still going to have the weaker valvetrain components, but they will probably last longer.
fozzi58
Full Access Member
My AFM\DOD has been disabled since 18k miles with a tune (you don't need to go that route - just the disabler is fine). She's just flipped to 107k and a lot of hard miles on her. Factory valvetrain is still intact but I also change oil every 3k.
Gearz
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I have had Range Technology AFM delete for 10 years and I won't drive the truck without it especially having dual exhaust the sound is just terrible in V4 mode. V8 power all the way!
You have asked a question that many have asked before. I’ve decided after 8 years of owning vehicles with the AFM that the question is unanswerable because no one can predict the future. I sold our 2011 Suburban with 160k miles and bought a newer Escalade trying to avoid lifter failure due to the high mileage. Well, 6 months/12k miles into ownership I ended up with a stuck lifter and a bent push rod on the newer vehicle. I plan to write a post about it at some point. Lessons to be learned in the whole process.
Marky Dissod
Full Access Member
With 100% accuracy for each specific iteration? No, of course not.
But this is like saying, maybe I don't need to wear my seat belt, it might not save my life at anytime during this specific drive.
Frankly, the seat belt has NEVER protected me ... so far ...
Disabling Engine Half@$$ does not guarantee that the two mode lifters will not fail in the future.
Leaving Engine Half@$$ on does not guarantee that the two mode lifters MUST fail in the future.
HOWEVER
Disabling Engine Half@$$, even with just a plug-in, WILL extend the serviceable life of the TCC (can't tell you by how much, I'm not psychic),
and WILL improve the odds that your two-mode lifters will last longer.
Please note that changing motor oil sooner / more often than GM's OLM suggests also helps; how much sooner / more often is up to you.
Which brings me to my next point:
And you don't blame the previous owner at all, whatsoever?
PatDTN
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Here's my opinion (all of these responses are opinions.) I had a problem with my stock 5.3 when it suddenly started guzzling oil and got the same list of responses. I bought a junkyard 6.2 from a newer Yukon and went through the physical process of blocking off the oil passages to the odd lifters, buying all new lifters, an LS9 cam with all new valve springs and valve guide seals. I went through the engine while I was at it and replaced the oil pump pickup O-ring which was clearly failed cleaned up some stuff etc.
I dropped that engine in and after struggling through tuning for the new engine and loss of AFM experienced the same symptoms with the new engine. I came to find out both upper catalytic converters had failed, collapsed, and blocked the third cat downstream leaving nowhere to get the exhaust out. That pushed the oil up into my intake.
I replaced the Y pipe with new cats and things have been fine.
Based on the enormous number of engines on the road with AFM I think the number of failures must be a very low percentage. Keeping the oil changes up to date, using a quality oil (don't use diesel oil if you have cats because diesels use zinc in the oil that destroys cats) and generally keeping things clean will almost certainly keep your AFM alive and well.
When I had it working I never felt the change between 4 and 8 cylinders.
The 6.2 is a blast with the LS9 cam but uses premium fuel at an alarming rate. So much so that I'm probably going to sell the Tahoe soon. I love the truck, I hate the fuel cost.
I dropped that engine in and after struggling through tuning for the new engine and loss of AFM experienced the same symptoms with the new engine. I came to find out both upper catalytic converters had failed, collapsed, and blocked the third cat downstream leaving nowhere to get the exhaust out. That pushed the oil up into my intake.
I replaced the Y pipe with new cats and things have been fine.
Based on the enormous number of engines on the road with AFM I think the number of failures must be a very low percentage. Keeping the oil changes up to date, using a quality oil (don't use diesel oil if you have cats because diesels use zinc in the oil that destroys cats) and generally keeping things clean will almost certainly keep your AFM alive and well.
When I had it working I never felt the change between 4 and 8 cylinders.
The 6.2 is a blast with the LS9 cam but uses premium fuel at an alarming rate. So much so that I'm probably going to sell the Tahoe soon. I love the truck, I hate the fuel cost.
I don’t. He took great care of the vehicle, and it had good service records from the dealer. I believe it sat too much in the last year, and that resulted in the issue. The oil hadn’t been changed in almost a year when I bought it, but that was because it had only been driven 300 miles in the last year.
intergalactron
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I drove a 2013 Silverado for 3 years and about 75,000 miles with a disabler. Maybe more. Then when they lifter noise got too excessive, I did a full-on AMF delete with a new cam and lifters. Never missed the AFM either way.
Marky Dissod
Full Access Member
So, in AFM's OPINION, was it that the oil hadn't been changed in almost a year,
or
that it had only been driven 300 miles in the last year,
that was grounds for one of your lifters failing you?
... Or was it GM? ...
PatDTN
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If these things were a constant problem GM's beancounters wouldn't let GM continue adding an expensive piece of equipment when they'll fight over a 10 cent increase for a better part for any piece of a car. When you make enough of anything you're going to have some failures.
Nashoba
Full Access Member
And what brand and weight oil do you use every 3K miles for oil/filter changes?
I put 207,000 miles on my 2011 Yukon Denali XL V4/V8. I feel like I saved over $20,000 in fuel costs over the life of it. I suspect the auto stop/start on my 2023 could likely pick up 5 miles per gallon on the road, but I disabled it anyway.
Let's face it. If AFM is a problem it will cost a bunch of money to fix it, starting with new heads and some computer programing. But, you can mess around with some performance heads and maybe a camshaft at the same time. I would have done that had mine gone out.
On a more serious note I have a rigorous maintenance plan for all my cars. Filter every 5,000 miles, oil and filter every 10,000 miles. I run 5/30 Amsoil Signature and filters. Driving was mostly freeway so the oil was always warmed to operating temperature. I never heard a peep from AFM. It is the luck of the draw. On the last road trip I did some 90 mph multi-car passing on some two lane roads. Car used zero oil. Sold it to some friends. They love it, as did I.
One side note. I always ran 87 octane in my 2011. In the year I sold it I started putting premium in it on road trips. It made a significant difference difference in power. I could feel it. I was floored.
Bought a 2023 to put on the road. It too will get premium on the road. It is exceptionally comfortable and quiet. I figure we will be at 100,000 miles by 2027. Hope it does as well as my 2011.
Let's face it. If AFM is a problem it will cost a bunch of money to fix it, starting with new heads and some computer programing. But, you can mess around with some performance heads and maybe a camshaft at the same time. I would have done that had mine gone out.
On a more serious note I have a rigorous maintenance plan for all my cars. Filter every 5,000 miles, oil and filter every 10,000 miles. I run 5/30 Amsoil Signature and filters. Driving was mostly freeway so the oil was always warmed to operating temperature. I never heard a peep from AFM. It is the luck of the draw. On the last road trip I did some 90 mph multi-car passing on some two lane roads. Car used zero oil. Sold it to some friends. They love it, as did I.
One side note. I always ran 87 octane in my 2011. In the year I sold it I started putting premium in it on road trips. It made a significant difference difference in power. I could feel it. I was floored.
Bought a 2023 to put on the road. It too will get premium on the road. It is exceptionally comfortable and quiet. I figure we will be at 100,000 miles by 2027. Hope it does as well as my 2011.
