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2014+ AFM (Active Fuel Management)

Ron.s

By Ron.s
in Engines & Drivetrain

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Canary59 Enthusiast

Canary59

Posted
Posted

I to am not to sure about its consistency but think I need to reserve judgment till the weather warms up. Sometimes when at operating temp it's in v4 mode most of the time. Next day at the same temp I can't see any v4 at all. Maybe it knows something I don't.

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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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gone_fishing Enthusiast

gone_fishing

Posted
Posted

I too have noticed a definate pattern between outside temp and V4 mode. When its -20F it won't go into V4 even at 55MPH. The warmer it gets the more V4 mode operation I see (along with better MPG).

seamonster Enthusiast

seamonster

Posted
Posted (edited)

I think if they did away with the indicator most of the problems would be gone.

Just drive the truck and let the computer decide what gear to be in and how many cyclinders are

active. I know this is not easy I am anal about my vehicles and worry about everything.

If it doesnt make a difference in MPG I wonder why they would put it in there. It has to

cost them money to build it in there and definately makes some people unhappy so if it doesnt

increase MPG why are they doing it?

Government MPG regulations maybe?

Edited by seamonster
TxTruckMan Senior Enthusiast

TxTruckMan

Posted
Posted

I did read someplace that when coasting the injectors cut off completely and the engine is turned by the drive train. This might explain some of what people are experiencing.

  • Like 1
losky79 Enthusiast

losky79

Posted
Posted

On my 4.3 I feel a quick vibration throughout the entire truck when switching from V4 to V6 mode driving in the city, although I never feel it while on the highway or interstate. It only happens when I am driving between 30-40 mph at about 1000-1500 RPM.

 

Is there a way to just deactivate AFM completely?

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

Im surprised how long it stays in at slow speeds foot off gas. Then it feels like a downshift then the trans downshifts, sometimes jerky. I just put it m5 in town smooth as glass no change in fuel mileage. After 45mph I go to m6 or drive. I wonder if the mile or two per gallon you get with it is worth some of the oil problems some people have had with it. I get no change in town.

8KCAB Enthusiast

8KCAB

Posted
Posted

Mine will vary from completely seamless to feeling like the truck is shifting down (still pretty smooth), just depends on the load required.

 

I have also noticed the amount of time in V4 changes with the weather. Got up in the 50's for a day last week, and the truck spent alot more time in V4 than it does in single digit temps. Brought my average mpg up nearly two miles that day.

pm26 Senior Enthusiast

pm26

Posted
Posted

We have a 2013 crew cab 4x4 Silverado with the 5.3 engine and 6 speed auto transmission at work. It does not have the DIC display as it is an LS model. I cannot tell when the AFM is activating/deactivating when driving the truck.

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

I got one for you, my sister in law was driving her Hemi car thru Dallas and it quit. They haul it to the dealer, timing chain at 40,000 miles. They told my brother to put a tune in so it wouldnt go to v4 that's why the chain broke. He told to put that in writing. See where that goes. The are fixing it under warranty.

mike94silverado Senior Enthusiast

mike94silverado

Posted
Posted

I've driven two trucks with t and they both act noticeably different and I drive the same.... Not going I worry about it on my current one it's a truck and every little bit helps

 

 

Sent from my iPhone using Tapatalk

kurtg2020 Enthusiast

kurtg2020

Posted
Posted

With a few more miles on peoples truck, I wanted to see if anyone else can feel the transition for V8 to V4 or the other way around. I assume that this is what I am feeling, if I have my cruise set for 60, I can feel the truck and watch the tac and know when the transition is taking place. No matter if it goes from 4 to 8 or 8 to 4, my RPM's increase slightly, I mean slightly, makes the needle jump and there is a slight "jerk" I would call it. Do others have a slight increase in there RPM's, again it does not jump 500, I would say maybe 100 RPM's but enough to notice the needle jump. I know its not a transmission shift, because it can be on a flat road, and I can watch the indicator light switch. Didn't know if anyone else's truck acted this way?

pm26 Senior Enthusiast

pm26

Posted
Posted (edited)

On my 4.3 I feel a quick vibration throughout the entire truck when switching from V4 to V6 mode driving in the city, although I never feel it while on the highway or interstate. It only happens when I am driving between 30-40 mph at about 1000-1500 RPM.

 

Is there a way to just deactivate AFM completely?

I hope a V6 switches to the V3 mode, not V4 mode. Gm installed the AFM system on a 2007 V6 3.9 liter engine used in Impalas but after one year they removed the system. I wonder why.

Edited by pm26
  • Like 1
kurtg2020 Enthusiast

kurtg2020

Posted
Posted

^ no. that is not your AFM. Let us know what dealer says.

Thanks, you are a bearer of good news! :) My seat is popping also, so when I get my oil changed I will tell them, At first I thought it was something with my cruise because when I don't use it, it is not as pronounced, but the good thing I guess I can reproduce over and over so the dealer doesn't think I am bat $hit crazy.

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