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Looking to buy first Silverado and afm is making it hard


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It is the internet, people come here to complain and can say what ever it is they want to make their statement seem true even though it isn't. Case in point, those that say AFM never activates and they get the same MPG in V8 as V4 mode, or those that say AFM is the root cause of most every major engine failure or issue; or my favorite that GM made these engines take 8 quarts because of AFM issues...

 

Fact is what you are hearing is a few people who are stuck in old ways with out actual large volume first hand experience, all they do is regurgitate what they hear from a few regular offenders online. Kind of like what you are doing OP with this thread about AFM issues, what you mention mostly pertains to first gen systems and being adapted (this is the same thing going on with DI that people get their panties in a wad for no reason and spout off catch can every chance they get because of what they hear on 1st gen DI cars adapted to DI); the last decade or so have been mostly trouble free.

 

Sure there are some rogue failures as with anything (Ram air suspension, Ford turbo's, Toyota cam shafts, ect) but I promise if you look around you will see it is such a small percentage (think less than one tenth of one percent range) that it is nothing to worry about. Are you going to not purchase anything because of a .05% failure rate? If that is the case you better get used to walking, either way that is what a warranty is for.

 

Buy what you enjoy, do your homework, if you are that scared go buy another brand and take their risk. You just have to be able to read through all the BS to get the answer you want and that takes time reading and studying. For what it is worth AFM has been out for 15 years on GM V8's and it does work to save fuel (GM wouldn't waste hundreds of millions if it didn't), even more so with this new gen specifically designed for it. We have had 4 trucks with AFM, longest going to 140k, none eating oil and we do regular maintenance. One of my best friends just got rid of his Tahoe for a new Sierra, he is in sales and drove a ton and had just over 210k on the clock, no issues or oil consumption and he had it regularly maintained. That is the key, maintenance. Good luck on your search.

 

Tyler

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3 hours ago, SierraHD17 said:

I wont argue if it works for you at whatever speed you drive with a 6 cylinder truck but I question you this on the first part.  How many afm equipped engines have you ever torn down?  Any?  I have and it's not a coincidence how the 4 cylinders that cycle are full of enough carbon that the rings are stuck in the ring lands.  It's enough of an issue GM has tsbs out for the dealers for piston and ring replacement.  It is what it is.

Okay we are half way there. The AFM is 'load' sensitive and the biggest drag at steady state is wind resistance. It isn't the AFM's fault your choices deprive it of benefiting you so a blanket statement about it's function from someone that chooses to operate outside it's limits to hinder others not so inclined? Really? To what end? 

 

Your statement hinges on the word COKE. I'm tell you flat out you can't coke rings by deactivating a cylinder to produce less heat than it would if active. That is what it is. Coking temperatures are in excess of 900F when a catalyst is in play and much higher when not. I have allot of seat time at an FCC. So what things can cause temperatures high enough to produce COKE.

 

There are things that can happen that will generate enough heat to coke motor oil and I've seen that plenty of times in non AFM motors. Detonation. Loss of lubrication. Loss of coolant. Ultra lean operation. Excessive load. Ultra tight clearances. Improperly prepared surfaces. Use of garbage lubricants and filters. Extended intervals of same crap oils. I've seen it get a motor so hot it blues cast iron blocks and steel main caps. It isn't a AFM thing. 

 

Those rings in deactivated cylinders are flooded with cooler oil from the spray jets. My 'guess' would be those ring sets are several hundred degrees cooler than active cylinders. Something stinks here. 

 

 

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To be clear, exactly nothing in my response had anything to do with "old generation" AFM systems.  That's how the current system operates.  The failures I was speaking of were only from this 2014+ section, where dozens (maybe more if you count them all) of users have needed their valvetrains to be rebuilt and more than a few have needed entire engine replaced due to failure of the AFM system.  To not acknowledge the risk posed by the system, even if small, is to bury your head in the sand.

 

It also had exactly nothing to do with "being stuck in old ways."  As an Engineer, I'm a huge fan of new technology in all things mechanical.  However, I believe the consumer is always better off when the changes are consumer driven, not driven by politicians (CAFE standards).  If people are willing to accept the added cost and reduced durability of a particular system in order to save a little gas, they will pay for it and companies will build it.  When activists (who frankly don't like cars in the first place unless they're electric) force manufacturers to incorporate these changes, whether the consumer wants them or not, whether the consumer is better off for them or not, that hurts the consumer with reduced choice and products they are less happy with (not just AFM, how about all the 3.08 geared trucks?  How many people with 5.3's would love 6.2's instead, but couldn't get them because GM has to limit their numbers?).

 

For example, I'm a huge fan of Direct Injection as it does offer an increased power potential and efficiency of gas engines.  However, I'm not going to bury my head in the sand and try to argue that it was "ready for primetime" on these and many other engines--that there are no adverse consequences to the system.  There simply are.  I have yet to see any evidence offered by those who claim it has caused no issues in 100K+, 200K, etc, miles.  Try taking your truck to a dyno at 150K and seeing how much power it's actually putting out compared with new.  Then dyno it again with a set of new heads where the airflow isn't significantly reduced by carbon buildup on the valves.  That would be evidence.   Luckily in this case, the manufacturers are solving this issue (dual injection including port injection that helps keep the valves clean) so DI issues may not be anything to worry about anymore for future engines.  But if you don't acknowledge there are issues to begin with, it's hard to also be a fan of the new technology that will solve them.

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51 minutes ago, Grumpy Bear said:

Okay we are half way there. The AFM is 'load' sensitive and the biggest drag at steady state is wind resistance. It isn't the AFM's fault your choices deprive it of benefiting you so a blanket statement about it's function from someone that chooses to operate outside it's limits to hinder others not so inclined? Really? To what end? 

 

Your statement hinges on the word COKE. I'm tell you flat out you can't coke rings by deactivating a cylinder to produce less heat than it would if active. That is what it is. Coking temperatures are in excess of 900F when a catalyst is in play and much higher when not. I have allot of seat time at an FCC. So what things can cause temperatures high enough to produce COKE.

 

There are things that can happen that will generate enough heat to coke motor oil and I've seen that plenty of times in non AFM motors. Detonation. Loss of lubrication. Loss of coolant. Ultra lean operation. Excessive load. Ultra tight clearances. Improperly prepared surfaces. Use of garbage lubricants and filters. Extended intervals of same crap oils. I've seen it get a motor so hot it blues cast iron blocks and steel main caps. It isn't a AFM thing. 

 

Those rings in deactivated cylinders are flooded with cooler oil from the spray jets. My 'guess' would be those ring sets are several hundred degrees cooler than active cylinders. Something stinks here. 

 

 

And exactly as I thought.  You have never taken any modern LS apart ever.  Fair enough.  That said I am calling the black carbon build up in the ring lands what it looks like and what GM calls it.  You can correct me if you like but it is what it is..... like everything else here.  I can go on for days for the failures I have seen from lubrication or lack there of but it's not relevant to the discussion at hand.  You do understand thermal expansion correct?  That's what you are dealing with causing the issues on the cylinders seeing active heat and cool cycles.  

 

Outside of operating limits?  Really?  It's called driving the speed limit like the rest of the planet.  If you choose to drive slower than the posted limit thats on you.  And since I don't live on any freeways its 100 km/hr... slower than your 75 mph interstates by a good margin.

 

Good talk though, I am out!

Edited by SierraHD17
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8 hours ago, Brummie99 said:

I've had my Silverado 1500 LT for 6 months now and just passed the 8,000 mile mark. At first I found AFM to be a bit of a novelty but find it clunky. I can definitely feel when it kicks in or out although it's not too intrusive.

If you are experiencing a clunky transition between V4 and V8 then you should take your truck in for warranty work.  I know that  after reading some of the negative perceptions of the design and function of AFM  your expectations may be lowered.  However, it was designed to operate properly and not to impede the life expectancy of other engine components.  Defeating this function  is a waste, imo.

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I bought my '17 5.3l new and have had it for almost 15 months and 11,000 miles now and I still hate the AFM.

I haven't had an issues this far, but I'll get a tune one of these days.

 

I can feel it EVERY time it cycles on or off, while my wife couldn't at first.

 

We (and by we, I mean I) used to play the "AFM game" where I call out "4" or "8" and she has to look at the DIC and tell me if I'm right or not.

(I'm really good at that game so it's just annoying to her now, haha)

 

I get some gnarly twangs and bangs sometimes but we've got alot of gradually inclining and declining roads and I think they help "confuse" my truck.

Edited by TheBlackPearl
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10 hours ago, SierraHD17 said:

My own truck... 2015 6.2 double cab.  Sitting stock with the 1" block removed out of the back of the truck on stock rims and tires.  I turned off the afm and did nothing else tune wise with it.  The truck got the same economy average on a 65 mph on cruise highway trip as it did prior.  The system never activated at that speed in the first place unless coasting downhill in which case the deceleration fuel cutoff negates the afm anyway.  I'm not the only one.

 

Did you have to get new u-bolts when you removed the rear block?

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11 hours ago, Donstar said:

The idea of running cylinders as necessary is brilliant, imo.  There may be some "growing pains" but the idea is sound.  I remember when engines were introduced that burned "unleaded fuel only"  were wrought with criticism.  I'm sure the introduction of EFI (electronic fuel injection) had haters as well.  Reduced fuel consumption is a good thing whether it is mandated or not as it leaves more money in my pocket..  Being easier on the environment is a bonus!

Yeah....the new DFM is probably gonna be sweet as honey!  It's the least of my worries....even the 900's I drove that ALL HAD AFM issues I never found 1qty?  Yes, they sucked up oil 1qt to 1qt&1/2 every 5,000-6,000 miles but never had mechanical issues with those?  So if the 900's all had lifters fail due to AFM than I guess the K-2's are fractionally better if you go by reading these forums?  Hmmmmmm I bought an ECOTEC3 for simplicity sake folks and AFM is the least worry of mine 

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5 hours ago, SierraHD17 said:

And exactly as I thought.  You have never taken any modern LS apart ever.  Fair enough.  That said I am calling the black carbon build up in the ring lands what it looks like and what GM calls it.  You can correct me if you like but it is what it is..... like everything else here.  I can go on for days for the failures I have seen from lubrication or lack there of but it's not relevant to the discussion at hand.  You do understand thermal expansion correct?  That's what you are dealing with causing the issues on the cylinders seeing active heat and cool cycles.  

 

Outside of operating limits?  Really?  It's called driving the speed limit like the rest of the planet.  If you choose to drive slower than the posted limit thats on you.  And since I don't live on any freeways its 100 km/hr... slower than your 75 mph interstates by a good margin.

 

Good talk though, I am out!

I haven't opened one because I haven had the need. I'm not having an issue nor do I expect I will. When I do I'll let you know. That said would you have preferred I lied? Your experience is the only one relevant? Get a grip. 

 

Speed limit here is 55 mph. 70 Interstate. Highway is good enough for me. I choose it. 

 

I care little what GM calls it. Coke ain't happen at NORMAL operating temperatures. Simple 8th grade chemistry. 

 

Now we pass my limits. Those of sensibility. You all have a nice day. 

Edited by Grumpy Bear
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To the op, I too was leery when I purchased my 2014 crewcab with 6.2 and 3.73 max tow package. The then new DI engine with AFM was an unknown deal and I had intended to have it disabled if it gave me any problems. It never did. Truck now has 60K and it still runs and operates as smoothly with the AFM active as the day the truck so new. And that includes pulling a 7K trailer on occasion. The switching between 4-8 cylinders is seamless and has never drew attention. Engine runs strong as ever, doesn't use oil, and gives me an actual 17 MPG average. Now, maybe I'm one of the lucky ones, but I wouldn't hesitate to buy another one.     

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If the simplest system were the best system then the 3.3L Ford Flathead model A power plant would still be the best powerplant ever built. Maybe it was. Plenty of those still ticking. Or maybe an old hit and miss engine? How about that for simple?

 

If complexity were an automatic death sentence the D16 series Honda should have dropped like flies at a Raid festival and yet there are plenty of 350K + motors still ticking and taking a licking. D***  few motors have a better reputation for reliability or economy both in fuel and in thrift of maintenance. 

 

Absolutely no one I've ever asked on this forum (or any other) has ever provided the failure rate in units per hundred thousand (standard measure for such things) to me when I ask for it but insist that without verification of this sort that I and the forum public drink their Kool-Aid. What absolute rubbish.  Give me a number that can be verified that supports the dooms day claims and I'll shut up. Until you can you got nothin but a statement that says, "It's so because I say it's so". I don't care how many anyone has 'personally seen" or rebuilt.  Without that number it just mud in the water. Didn't buy that crap when I was five from my mother and you guys ain't THAT special.

 

If the OP was getting replies framed as OPINION what could I say? Not a thing. But the replies are being presented as facts. Facts NO ONE has been able to statistically verify. Stated as facts that defy logic, chemistry and physics. What did he do to deserve that sort of cruelty? 

 

It's one thing to say "it happens" it's quite another to scream Fire in a theater when the fire is a BIC lighting a smoke in the boys room of some ignorant sixteen year old. 

 

My Michelin Defenders went flat. Ergo ALL Michelin tires are crap. Oh boy!  Stay away from Michelin!! To complex. See it my shop every day. Good grief Charlie Brown. D'oh, nail! :loser: 

 

Ridicule me all you like. Make fun of my methods and ideas. I'm not the one breaking stuff am I? 

 

 

    

Edited by Grumpy Bear
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I bought a 2017 w a V6 and have had absolutely no problems w AFM.  With that being said, once my powertrain warranty expires, I'll get a tune and turn it off.  Why take even a small risk when you can eliminate the risk by spending a little more on gas and a tune?  With that being said, I've only driven the truck 2320 miles in 10 months.  Hoping it can last 20 years!

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37 minutes ago, Grumpy Bear said:

Facts NO ONE has been able to statistically verify.    

I disagree.  What failure rate are you looking for, failure rate of what compared with what?  One single AFM lifter failing and causing damage to one single engine in the fleet provides an infinitely higher failure rate than an otherwise identical engine that has no AFM lifters making that mode of failure impossible.  It's like arguing the odds of cutting yourself while juggling knives is very low if you are good at it.  Just one cut makes your rate of cuttage from juggling knives infinitely higher than somebody who does not attempt to juggle knives.  This line of reasoning would only work if you believed that no AFM lifter had ever failed and caused damage.  We all know that isn't true.

 

45 minutes ago, Grumpy Bear said:

Absolutely no one I've ever asked on this forum (or any other) has ever provided the failure rate in units per hundred thousand (standard measure for such things) to me when I ask for it

 

That's probably because information like that would be Proprietary (or ranked higher) GM information.  Anybody with access to it who released it would not only be fired for it, but held legally liable [just as it says in the Protecting Proprietary Information Agreement (or whatever GM calls it) that they likely make their employees with access to such information sign once a year].  Asking for information that is impossible to obtain is not a reasonable argument.

 

All we can do is read the tea leaves:

 

https://static.nhtsa.gov/odi/tsbs/2016/SB-10078567-7690.pdf

 

Note, there is no equivalent TSB for standard lifters spontaneously failing.  Note to amxGuy1970, that TSB is not for old engines.  Note they acknowledge a chance this has caused the lifter to be stuck or spun in its bore.  When that happens it's very likely to ruin the camshaft, and a ruined camshaft (if bad enough, if the condition existed long enough) can easily turn the engine into a large paperweight as metal filings in the oil have caused damage throughout.

 

Note they identify the most likely cause as a failure of the locking pin in the AFM lifter.  A standard lifter will never fail due to failure of the internal locking pin because standard lifters do not have internal locking pins.  Standard lifters don't juggle those knives.  No cuts ever for them.

 

I think we can agree, the mere existence of this TSB is proof that this mode of failure does, in fact, happen. 

 

I agree that the failure rate data would be nice to have, it's hard to make an informed choice without it.  But consumers must do that every day with virtually every product we buy.  All we can do is read the tea leaves and make a choice based upon how we read the leaves and what is most important to us.

 

For me, reliability is important.  I go on 2,000 mile roadtrips with the family and spend time out in the boonies, miles from pavement where there is no cell coverage and an engine issue would mean walking back to civilization (or riding a horse if I was lucky enough to have brought one).  Even the thought the damage would be covered under warranty (if lucky enough to have it happen in the next 7 months before my warranty runs out) is nice but little solace compared with the thought of the truck being stuck in some dealership 1000 miles from home for a month or two.  That goes so far beyond an inconvenience, I'll do anything I can to reduce the odds of it happening.

 

And since the speed limit across most of Montana is 80 MPH, I would not likely realize much gas savings from the system anyway, even if the truck was stock.

 

Others, for whom saving gas may be highly important, can choose to keep the system active.  And that's a reasonable choice for them.  But doing so without acknowledging they are even making a choice, believing there is ZERO chance of a failure because of that choice is naive.

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Poor Op.  His plea for advice has probably exacerbated his dilemma!  What I have summarized from this thread that as long as we acknowledge that the chance of failure of your AFM is greater than ZERO then you are not naive and good to go ahead and purchase a Chevy!  

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In conclusion, if you are that worried about it buy the dealer backed extended warranty. Or lease. If don’t drive lots of miles and pay it off, keep paying the payment to a savings account for repairs. Stay on this website people are pretty good about keeping readers updated on service bulletins.


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