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2014+ AFM (Active Fuel Management)

Ron.s

By Ron.s
in Engines & Drivetrain

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Grumpy Bear Senior Enthusiast

Grumpy Bear

Posted
Posted
14 hours ago, truckguy82 said:

When justin from blackbear tuned my truck in person (i was driving he was tuning in passenger seat)

 

he said some trucks have a noticeable issue with it and some are smooth as butter. I would imagine not many people on earth have been in a larger number of trucks and paid attention to the switching action.

 

Since I never notice mine, before he told me that I thought everybody complaining about afm switchover were whining grade school girls.

 

 

I'll buy that even without knowing what Justin means by 'noticeable'. :thumbs:

 

Now at 111,000 miles and for the majority of those miles having the Scan Gauge II monitor running I can finally notice the AFM in/out. So can I notice it? Well...sometimes :) It took allot of training though and it is by no means consistent.  So...yea, it's noticeable in the narrowest  sense of the word. Enough to drive me to distraction? Herky-Jerky? No. That given I will concede that we all have different sensitivities and tolerances for such things. I can't hear as well as my grandchildren nor can I drink a cup of coffee as hot as my father. I'd say, if you can feel it like the 'bump' of a factory TH-350 2-3 shift, it needs to be looked at. 

 

Pepper has enough miles the exhaust has more 'tone' to it than it did new as is the case with factory exhaust and I can finally hear with my not so good ears a mild change in pitch when in DOD IF the wind is behind me so as to cancel out wind noise over the cabin. Vastly different than a helicopter or drone. More like the sound difference of one fret lower on the same string. My wife on the other hand can hear a flea fart in a hurricane and she doesn't hear the difference at all. Go figure. I honestly think I notice it like one notices a 1960 yellow VW. Ya never do until you've owned one. Then there everywhere. 

 

I've thought at times that perhaps final drive gearing that is lower than her 3.23 just might make it more noticeable. That would make an interesting pole. 

 

 

 

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oldmann
oldmann

Why are people so concerned about this topic. I do not understand it. Just drive it. End of story. And yes, even if you can't figure out why the truck has it, it is to save fuel.

pm26
pm26

No, it does not. Not even close. The only Cadillacs that possibly exceeded the weight of 2014 GM crew cab 1500 4x4 pickups were the old land yachts (1976 and older) models. I believe that a 1976 Ca

seamonster
seamonster

Whats up with the name calling?   Cant you see we agree----the AFM feels like a gear shift!   Many people want 6 and 8 speed tranny and then complain they can feel AFM. That is what I dont unders

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KARNUT Senior Enthusiast

KARNUT

Posted
Posted
When justin from blackbear tuned my truck in person (i was driving he was tuning in passenger seat)
 
he said some trucks have a noticeable issue with it and some are smooth as butter. I would imagine not many people on earth have been in a larger number of trucks and paid attention to the switching action.
 
Since I never notice mine, before he told me that I thought everybody complaining about afm switchover were whining grade school girls.
 
 

I’m a must be one of those girls. I can tell in any vehicle that I been in when it does it. Honda, Ram, GM. Being a long turn amateur drag race driver, builder I’m in tune with my vehicles. I feel everything. I will not buy a Frankenstein V-8 or V-6. When I buy an engine, I want it all, all the time. I go cry in the corner now.[emoji22][emoji22][emoji22][emoji22][emoji22]


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truckguy82 Senior Enthusiast

truckguy82

Posted
Posted
58 minutes ago, KARNUT said:


I’m a must be one of those girls. I can tell in any vehicle that I been in when it does it. Honda, Ram, GM. Being a long turn amateur drag race driver, builder I’m in tune with my vehicles. I feel everything. I will not buy a Frankenstein V-8 or V-6. When I buy an engine, I want it all, all the time. I go cry in the corner now.emoji22.pngemoji22.pngemoji22.pngemoji22.pngemoji22.png


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You wouldnt notice mine, no way.

 

might notice the exhaust note, but that’s not what im talking about

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KARNUT Senior Enthusiast

KARNUT

Posted
Posted
You wouldnt notice mine, no way.
 
might notice the exhaust note, but that’s not what im talking about

That’s where I noticed in the several Rams I’ve been in. My 14 GMC I noticed both. The couple Honda’s with feel. If you have noisy over sized tires you probably wouldn’t notice. Prior to my 14 I had exhaust to cover wind noise. My 14 was silent. I’ve not been in anything before or since as quiet. I put my exhaust back to quiet because of that. But no matter feel or noise I don’t want it. To much extra BS to support it. If I want 27MPG I’ll drive my wife’s car. My 20MPG HWY 02 4 speed Avalanche is only 2-3 MPG off my 14 GMC. My engine, transmission, would be 1/2 as much to replace. I’m confident it can go up to 300K. My brother in law has had two in those years model. Working on two more with 200K plus. I know several more working on that. These new Frankenstein trucks I doubt it in those type of numbers. Grumpy probably, he’s what they call an outlier I believe.


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WilliamBos Senior Enthusiast

WilliamBos

Posted
Posted
On 1/7/2014 at 2:47 PM, RyanbabZ71 said:

On our Tahoe (08) only knew when it kicked inbuilt watching the dash. It was seamless. Camaro had :) AFM it was seemless except for the audible noise through the exhaust.

 

 

Ryan

Like a ‘Hemi fart’? 

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  • 2 weeks later...
Outdoors_Guy_88 Enthusiast

Outdoors_Guy_88

Posted
Posted

Probably been covered, but I can't find it.  - How can I tell AFM is in 4 vs. 8 mode (while driving) in a 2015 Sierra 1500 5.3L with the basic display.  I see everyone talking about it with the better display, but I can find no indication on the simple displays.

3tspapat Enthusiast

3tspapat

Posted
Posted

It's in your dash display setting. A few of them will show V4 or V8 mode on the bottom. The fuel economy and trip meter ones will show it. 

  • 1 month later...
lryfer Enthusiast

lryfer

Posted
Posted (edited)

I just purchased a 2018 Silverado. Saw a orange V4 for an instance and wonder what that is all about.  Reading these posts my engine is to go to a 4 cylinder? WTF.

 

Runs down the highway like something is holding it back, hesitation as well when going on level ground or in cruise going uphill or downhill. Truck does not run as smooth as my 2006 Silverado.

 

With this said the engine per the RPO codes is a L83 Engine,  5.3 V8, ECOTEC3. So is there a button that i don't know about to make this function correctly to work with killing cylinders or  it does the killing itself. Took to dealer as concerned and they told me drives correct and nothing wrong with it. Said they did software update.

Edited by lryfer
lryfer Enthusiast

lryfer

Posted
Posted
On 1/8/2014 at 2:10 PM, bboyce536 said:

First time poster, but long time browser...

 

I definitely notice the switching between modes and unlike others, I seem to notice it more as the speed increases. It almost seems like my truck is trying to stay in V4 mode longer then it should..for example, on a small uphill I will start to put my foot in the throttle to keep my speed and it will stay in V4 so I keep pressing the gas and then it feels like it downshifts as it finally switches into V8 mode. Not sure if that's normal or not but it does bug me. This is my first GM with AFM...Kinda makes me miss my old 2011.

Agree my 2006 Silverado runs smooth compared to my newly acquired 2018.

 

CamGTP Senior Enthusiast

CamGTP

Posted
Posted (edited)

The V8 to V4 is done automatically, there is no input from the driver. When certain situations call for V4 mode, it will make the switch for fuel economy reasons. This stuff came out in 2005 in the 5.3 in the smaller SUV's like the trailblazer/envoy and 2007+ GMT-900 trucks. How you haven't heard about in the past 15 years is kinda crazy.

 

Either learn to live with it and let it do it's thing or buy a device to turn it off. There about 80 gajillion threads about the AFM disable devices.

Edited by CamGTP
lryfer Enthusiast

lryfer

Posted
Posted
16 minutes ago, CamGTP said:

The V8 to V4 is done automatically, there is no input from the driver. When certain situations call for V4 mode, it will make the switch for fuel economy reasons. This stuff came out in 2005 in the 5.3 in the smaller SUV's like the trailblazer/envoy and 2007+ GMT-900 trucks. How you haven't heard about in the past 15 years is kinda crazy.

 

Either learn to live with it and let it do it's thing or buy a device to turn it off. There about 80 gajillion threads about the AFM disable devices.

you forgot an option get rid of truck and get one without as i would hope they all aren't like this.  Only one time i have seen the V4 and i drive like an old man very conservative and don't get into the gas pedal. So why the V4 doesn't come on more then if driving like an old man is the question for me.

  • 2 weeks later...
lryfer Enthusiast

lryfer

Posted
Posted
On 3/13/2020 at 5:45 PM, j-ten-ner said:

Reason #1 for disabling AFM was for my own comfort.

Couldn't stand the transition between V4 and V8. Especially in combination with the 6 speed.

 

so long

j-ten-ner

What are the typical symptoms of this AFM issue? Just got a 2018 Silverado and it is terrible. Went into V4 once that i saw. Truck hesitates like crazy like something is holding it back from running smooth.b What is best AFM on market or is it worth it. Only got 6500 miles on the truck

  • 1 month later...
  • 2 months later...
flyingfool Senior Enthusiast

flyingfool

Posted
Posted (edited)

http://www.prestonmoore.com/2018_Sierra_L83/Melling-tech-bulletin-on-GM-LS-Deactivation-Lifter-Issues-3.1.18-1.pdf

 

most failures are pointing towards the solenoids in the VLOM , could be caused by cheap oils  causing sludge and conjestion of flow, blocking the vlom filter, or those super long extended oil drain intervals filling them with junk, or just poor manufactuering

Edited by flyingfool
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BigT2014 New Member

BigT2014

Posted
Posted

I used my hp tuner and for $100 for 2 credits it is now disabled and all is good.

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