2014+ AFM (Active Fuel Management)

Dj0nes · February 7, 2014

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.

It's highly unlikely the dealership will recommend a tune for a vehicle still under manufacture warranty.. Let alone a tune in general. Do you know what tune the dealer said to install?

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KARNUT · February 7, 2014

It's almost out of warranty, any that keeps it going on all 8. Some dealers don't care if you have a tune.

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KARNUT · February 8, 2014

I can't see how that caused it, any car with a stick would be hard on the timing chain. But that the reason they gave him.

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gmc1 · February 8, 2014

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?

I have noticed the same thing, or so I think. It's always out of the corner of my eye but I see the needle move slightly.

Edited February 8, 2014 by gmc1

kurtg2020 · February 10, 2014

So I was reading though the GM Techlink monthly newsletter I would call it, and I found this under the three new Silverado/Sierra engines and though it was interesting especially what the last sentence:

Active Fuel Management

Cylinder deactivation, also known as Active Fuel Management, is now standard on all three engines.The system uses oil pressure, controlled by the Powertrain Control Module, to deactivate the lifters on selected cylinders, closing the valves for those cylinders.It deactivates four of the cylinders on the V8 engines and two cylinders on the V6 under light load conditions — operating the engines as a V4 — and seamlessly reactivates the cylinders when the driver demands greater power.The transition takes less than 20 milliseconds and is imperceptible

Mine is defiantly not imperceptible, but talking with the dealer he said that I will more than likely have to wait for GM to acknowledge this issue and come up with a fix. But I have not officially taken the truck in yet, so maybe once they drive it, maybe they can reflash it or something to help with the transition.

brewguy101 · February 10, 2014

^^^ same here, we have a 2012 5.3 work truck with 2000 miles and i never can feel the transition. On our 2014 it is very noticeable, almost feels like a shift.

Edited February 10, 2014 by brewguy101

Dnt · February 13, 2014

^^^ same here, we have a 2012 5.3 work truck with 2000 miles and i never can feel the transition. On our 2014 it is very noticeable, almost feels like a shift.

My 2014 5.3 occasionally has a slight jerk going from V4 back to V8 mainly at low speeds I believe it only happens when the trans also downshifts at the same time but have not really checked that out just yet (now I am curious).. Does not bother me as it is identical to what my 2009 5.3 did (87k miles). I just thought it was NORMAL? I am not sure what their definition of seamless? I know that I can typically feel the 6 spd shifting gears I wonder if a 6spd transmission shift is supposed to be seamless? What was it Bill Clinton said it is according to what your definition of is IS LOL

Dnt · February 13, 2014

I think I have it figured out now. GM has developed a updated version of the mood ring (some people on here may not be old enough to know what a mood ring is they can do a google search if needed) and your new 2014 truck senses your mood. If you are a crabby old fart today you get very little V4 , if you are kind to young children and pet the dog instead of kicking it the truck senses that and gives you lots of V4 and better gas mileage. Watch your MOOD swings bichs. LOL

Silver space ship · February 13, 2014

Most of the time I get a jerk but I have had everything from smooth as silk, to so hard I looked I the rear view mirror because I thought I just got rear ended. It seemed the worst in the fall when it started to get cold out, now that it's winter it doesn't go into v4 but every so often like going down hill. Gas milage went from 19 to low 13's too but part of that is just winter gas and cold.

cobrajet84 · February 13, 2014

never notice the switch unless I'm looking at the dash.

KARNUT · February 13, 2014

Christine lives!

VMaxtastic · February 14, 2014

Mine literally clunks in and out of it. It almost sounds like its gearing down. So brutal

Dnt · February 15, 2014

losky79, on 03 Feb 2014 - 04:47 AM, said:

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.

I bet that ole 3.9 engine did go to V3 which would not run very well at all, that is probably why they burned it and probably why the new 4.3 V6 only drop 2 cylinders in AFM. These GM engineers are always learning very impressive.

AW22 · February 17, 2014

http://www.rangetechnology.com/pages/v8

I installed the Range Technology V8 AFM disabler, yesterday and so far so good. I did not buy the 6.2 to worry about modest mpg gain while running only 4 cylinders. Since Range is still in beta test mode for the 6.2 plug-in I was able to get it for $179 or -$20 off msrp, and it shipped it arrived Sat. Takes all of 15 seconds to plug into the OBD port under the dash, and that's it...No more cyclinder de-activation. I've only driven like 40miles so far but it works seamlessly, and I have not gotten any engine warning light triggered. No more lugging down the highway in 4 cyclinder mode. Range said all ECU's are different, and the reason for the beta test is to make sure they have the widest range of potential ECU timing in order to release a product that will work with highest percentage of 6.2 engines. They estimated aprox 5% of the ECU's will never be able to work with their disabler (something about timing the electronic pulses), so it's nice to be the "other" 95% as my truck so far has been as advirtised. I am driving 6hrs each way on Wed for a 4 day family trip, so will let you know if anything changes. Fot those who never want their 6.2 V8 to be half the motor you paid for this Range Technology disabler seems like the perfect answer for $199.

anthony2558 · February 17, 2014

I installed one on my '14 5.3L. No more senseless downshifting to correct lose of speed after going into V4. MPG's seem to be the same if not better for me. In my area of NJ with tons of rolling hills, AFM is more of a nuisance then benefit. Great product.

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