Poll.how Bad Really Is Afm

[jrbartholomew]

well this is my first poll i hope it works

[asilverblazer]

"rattles on start up" This is not because of AFM.

 

"exhaust sound with different exhaust" Well duh. (joking )

 

I voted works fine.

[jrbartholomew]

well question #4 was worded wrong. i meant did it sound bad in 4cyl mode and does it bother you

[Stevens03]

It works fine, just just doesn't make that much if any of a difference. In a car, it would probably do better but in a heavy truck, it just doesn't stay in v4 mode long enough.

[RyanbabZ71]

why o why

[jrbartholomew]

Well Ryan I was just curious. ive been visiting here for a few years and read alot and gain a lot of info.i have read on the AFM and was wondering if i have to worry about it on our Tahoe. dont want to start anything

thanks jeff

[Eddie 70]

At this point I think mine is working like it should. I have found when on the road if I use cruise AFM is more likely to come on than if I am using the gas pedal myself. I am happy with that. So far so good with my truck and AFM. I wish it would stay engaged longer and come on earlier just for the mileage benefits.

[seamonster]

Mine works great 6.0 with 4:10's, I can feel the cylinders kick in and out but I would expect that

so that is not a concern. Mine stays engaged for long periods. This is the amazin part---

I have a 17 ft aluminum boat that weighs about 2500 lbs on the trailer. If I push the tow Haul Mode

it will stay in 3 rd gear and then will go to 4 cyl mode and get 18 MPG on the hwy. I think the 4:10's

with the 6.0 allow it to work like it should because it has enough torque. Not knocking the 5.3 or

3:73's I have had them and liked them but this combination works for me..

Now I hope its not junk like some of the guys on here are saying, I do have a tuner and could

turn off the AFM but havent

[fbachman]

It works fine, just just doesn't make that much if any of a difference. In a car, it would probably do better but in a heavy truck, it just doesn't stay in v4 mode long enough.

 

From the consumers perspective, you are correct (I observe the same as well, no noticable difference) --- HOWEVER....

 

Don't know if this is related to AFM or not, but I recently rented a 4.8 Silvy EC, and drove a 600 mile round trip, almost all highway. Cruising at about 75-80mph, the 4.8 (no AFM) got, at best, based on my calculations, about 17.5 mpg, which kinda shocked me.

 

My 5.3, on the identical trip some years ago, averaged 19.5 mpg. It has AFM. This was in the dead of winter with an average amb temp of 35-40F. The 4.8 truck trip was a few weeks ago with outside temps in the 75-90F range.

 

Could be due to the different gear ratios, or a whole host of other things... but, my 5.3 did a heck of a lot better on the HWY than the 4.8 truck. AS said, no clue if AFM gets the credit, but just an observation.

 

I can almost GUARANTEE you that the AFM makes a significant difference on the EPA and MPG certification cycles than without --- otherwise it wouldn't be there and GM wouldn't have thrown a boat load of money into this intricate technology.

 

Not sure about today, but if you ever had the opportunity to see the mocked up mules they use for the mileage and EPA cycles (no where NEAR a road worthy vehicle (funcitonally or visually) 10 years ago..... I am sure there was a good reason for it from a cert perspective, whether the consumer would ever see the benefit or not....

 

Just my $0.05.

[Daryl LBZ]

I just don't like it because it seems to do nothing, seems to cut power at certain speeds and RPM's, and it made my exaust sound like crap in V4 Mode (Which was obviously going to happen). I had my tuned out, and havent looked back. My average gas mileage hasn't gone down either.

[2016 Sierra Owner]

I voted that it works just fine. I guess I am doomed now. I am having mine turned off with my tune though.

[Ryloth]

I was thinking about starting a poll on this too.

 

We are always more likely to post complaining about something not working than posting about something that is working just fine. After reading all the problems that might be related to AFM and all the other negative reviews about it, I was upset with my recent purchase.

 

However, it looks like those problems and negative AFM posts are hopefully not the norm.

[music]

Great poll. Too many negative comments on the forum about AFM, with little basis. Yes, some have had issues, and the forum focused on it heavily... but not many individuals from what I can tell. Mine is fine, and I'm certain it helps hwy economy. I get about the same in the 4wd w/ AT tires as in my previous 2wd ext cab 5.3 w/ a 3.42 rear and street tires.

 

Edit: I may be wrong, but I bet that AFM helps less w/ the 6-spds than the 4-spds. Mine pulls high enough rpms when cruising to see AFM enable *a lot*. I bet 6th gear rpms are too low to make good use of it.

[RyanbabZ71]

As of this moment (11:25am est 9/2/10) 69.8% have no problem

[music]

As of this moment (11:25am est 9/2/10) 69.8% have no problem

 

Only 6% have have indicated oil consumption issues (so far). Has anyone verified "start-up rattling" as being due to AFM? The "other issues" is subjective and the exhaust sound relates to aftermarket mods (not GM's design).