Interesting Article Segment I Found Regarding Disabling of AFM

[MaverickZ71]

On 2/11/2019 at 9:34 PM, TXGREEK said:

So, from what I’ve gathered here is there’s no proof it’s good to turn off your AFM or proof that it’s bad to leave it on?


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Like they say, it is what it is.  Unless it ain't.

[KARNUT]

Like they say, it is what it is.  Unless it ain't.

Actually there was in the pre 14 models. Some of the smokers stopped smoking, oil use went down when cylinder deactivation was turned off.


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[F4Gary]

1 hour ago, MaverickZ71 said:

1)  No risk whatsoever in turning AFM off.  2)  Many people on this website report no discernible difference in fuel economy with AFM turned off.  

I drove up to Kansas for the eclipse last year.  Going up with the Range device  vs coming back using AFM, I got 2 mpg better mileage using AFM.  Same speed both directions and it wasn't windy.

[Grumpy Bear]

5 minutes ago, F4Gary said:

I drove up to Kansas for the eclipse last year.  Going up with the Range device  vs coming back using AFM, I got 2 mpg better mileage using AFM.  Same speed both directions and it wasn't windy.

That's about right. Factory claim was 5-7% but I found it a big better than that. 

[SS502]

2 hours ago, MaverickZ71 said:

Like they say, it is what it is.  Unless it ain't.

HAHA...that's kin to "The more I know about what I know, the less I know"

[SS502]

29 minutes ago, F4Gary said:

I drove up to Kansas for the eclipse last year.  Going up with the Range device  vs coming back using AFM, I got 2 mpg better mileage using AFM.  Same speed both directions and it wasn't windy.

Nobody disputes that AFM does in fact help MPG numbers, it works as advertised. The problem is the whole system uses more moving parts. That introduces more things that can fail. I will say my old 2008 Avalanche had 186XXX miles when I sold it, never had a problem with AFM. But as GM keeps trimming down their warranty coverages the cost for repair falls on us. I personally don't really care about MPG but I know others do and they should care. If I did (again just me personally) I would have opted for the 5.3 or the 4.3 (both great engines) and run 87 octane.

23 minutes ago, Grumpy Bear said:

That's about right. Factory claim was 5-7% but I found it a big better than that. 

Grumpy...I don't think the GM engineers can replicate your MPG on a good day

[flyingfool]

try using V4 mode in tow haul, this increases power output by the 4 cylinders and stays in gear longer

[SS502]

21 minutes ago, flyingfool said:

try using V4 mode in tow haul, this increases power output by the 4 cylinders and stays in gear longer

I'm pretty sure you can't select V4 exclusively, the system identifies when there is the least amount of demand on the engine and transitions from V8 to V4 mode to save fuel, power does not increase in those 4 cylinders or in fact any of the cylinders. The shift mapping is altered in Tow/Haul mode to allow the engine to reach a higher torque band RPM (4100 rpm on the 6.2 is peak torque) to make towing easier on the entire drivetrain. Maximum horsepower (420) is attained when all 8 cylinders are working at 5600 rpm (again this is the 6.2). It is not possible (or shouldn’t be) to be in V4 mode during this operating environment.

[TXGREEK]

try using V4 mode in tow haul, this increases power output by the 4 cylinders and stays in gear longer

You can’t select just V4 mode


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[flyingfool]

6 hours ago, SS502 said:

I'm pretty sure you can't select V4 exclusively, the system identifies when there is the least amount of demand on the engine and transitions from V8 to V4 mode to save fuel, power does not increase in those 4 cylinders or in fact any of the cylinders. The shift mapping is altered in Tow/Haul mode to allow the engine to reach a higher torque band RPM (4100 rpm on the 6.2 is peak torque) to make towing easier on the entire drivetrain. Maximum horsepower (420) is attained when all 8 cylinders are working at 5600 rpm (again this is the 6.2). It is not possible (or shouldn’t be) to be in V4 mode during this operating environment.

i'm able to enter v4, and tow haul will also operate in v4 , it increases the rpm in v4, thus more power on 4 cylinders.. 

[SS502]

2 minutes ago, flyingfool said:

i'm able to enter v4, and tow haul will also operate in v4 , it increases the rpm in v4, thus more power on 4 cylinders.. 

How do you go into V4 with a load? Yes you can enter V4 while in tow/haul but unless you’re towing on a flat road or down hill with no load on the engine it should never go into V4 and it’s not selectable, it only (under NORMAL) transitions to V4 when there is no load if it does your truck is in need of repair

[flyingfool]

1 minute ago, SS502 said:

How do you go into V4 with a load? Yes you can enter V4 while in tow/haul but unless you’re towing on a flat road or down hill with no load on the engine it should never go into V4 and it’s not selectable, it only (under NORMAL) transitions to V4 when there is no load if it does your truck is in need of repair

i wasn't talking about towing in v4 not gonna happen, just mentioning v4 and towhaul improve the MPG  while on 4 cylinders

[SS502]

3 minutes ago, flyingfool said:

i wasn't talking about towing in v4 not gonna happen, just mentioning v4 and towhaul improve the MPG  while on 4 cylinders

Okay, I digress 

[Gagliano7]

Where i live there are no long stretches of flat roads and i do better mpg with the range than V4 mode. It switches way to much where i drive.

[Sierra Dan]

My '14 5.3 will often lock into V4 mode in what I call the sweet spot of around 40-45mph on flat, smooth roads which we have an abundance in the surrounding KC area.

More so than on the highway. Any slight throttle input will kick me back into V8.

Also, any slight headwind immediately kicks V4 back to V8