AFM Delete - how to tell if it was done?

[Centauri]

I bought my 2012 2SS used from a Chevy dealer. Love everything about the car, but the gas mileage is the same highway or street - right around 16MPG. Now, I know what I was buying when I bought it, and am not overly worried, but it would be nice to know if the AFM is in place. I have nothing to compare it to, but the MPG's do seem low for highway driving.

[SSEssence]

Listen to the exhaust while you're sitting in traffic, you should be able to hear it turning on or off.

[rshelar]

If you have the gigantic stock mufflers it is hard to hear but you can hear it. Once you get up to speed and lift off the throttle it will drop into AFM. Give it slight throttle and you will hear it kick out.
What makes you think it’s not there? It can be deleted with some tuning programs or the lifters replaced with engine work. I have the Range Module that plugs into the ECU. I have Magnaflow muffs and you can really tell. It drives me crazy when just driving around town. The MPG savings on the highway is only 5%. You’re still pushing a vehicle that weighs 4000 lbs.


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[Welker2]

As other have said, you should be able to hear the AFM kick in and out.

In my experience the AFM doesn't make that big of a difference in MPG. I make frequent trips to Northern California to visit family; 99% of the trip is interstate. On a trip just before installing the Range device to disable the AFM I reset the AMPG on the DIC; 1,300 mile round trip averaged 22 MPG. On the next trip, after installing the Range Device, averaged 21 MPG .. a difference of only 1 MPG. Both trips were almost identical, drove through the night to avoid traffic, cruised at 80+ MPG most of the way, temps were within 5 degrees between trips. As far as city driving, it has zero impact on MPG.

[TheFlyingBananaSS]

You will know.......trust me lol.

[Centauri]

Y'all say there is a sound - care to eleborate on what I should be listening for?

And if it's not the AFM - why the ultra-low MPG? I use the accelerator some, but not always. The car is low miles and was described when sold to me as 100% stock.

[JerTM]

I can't remember what mine got when it was stock, but it was around there unless I babied it then I could manage 19 with the manual trans. Utah isn't exactly the ideal terrain for perfect world mpg.

[rshelar]

Originally Posted by SSEssence

Listen to the exhaust while you're sitting in traffic, you should be able to hear it turning on or off.

Hey there SSEssence

We have the same car except I have the vert


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[Moto-Mojo]

There’s no mistaking how it FEELS! At light throttle, on LEVEL ground, you can feel the surge and how it might feel like if you were going 25 in 6th gear - with AFM on. (which it will try to do on a stock auto anyway which is annoying on 8 cylinders)

When it lights off the 4 dead cylinders, there is a small surge in power...unless you put your foot in it.

[qcman]

Originally Posted by Moto-Mojo

There’s no mistaking how it FEELS! At light throttle, on LEVEL ground, you can feel the surge and how it might feel like if you were going 25 in 6th gear - with AFM on. (which it will try to do on a stock auto anyway which is annoying on 8 cylinders)

When it lights off the 4 dead cylinders, there is a small surge in power...unless you put your foot in it.

This 100% and it will kind of fart when it lights those other 4 cylinders back up. As to gas mileage OP AFM sucks for that in general. Its a gimmick and nothing more.

My tuned auto is way better on gas running on all 8 all of the time. It doesn't do quite as well on a highway trip as AFM did but it was close. I drove my car to Quebec City a couple weeks ago and got 26 mpg on that trip at 70-75 mph which I thought was damn good for a car like this. Around town with too many hard romps to count I'm 16-17 mpg. It will do better than that if I'm civilized with it.

Did you reset your DIC and monitor what it said or calculate it yourself?

[rontammy0]

Its mostly around town. There is a distinctive exhaust note change...it sounds like a lawn tractor. As others have said..you will know.

[Chris49066SS]

Originally Posted by Centauri

Y'all say there is a sound - care to eleborate on what I should be listening for

With stock exhaust, the transition in and out of AFM is a subtle sound, definitely noticeable. At first, you'll think you keep hearing something and can't figure out what it is, but its there. As you upgrade your exhaust, it becomes way more pronounced, and eventually, extremely annoying, as it causes drone inside the cab as well.

The way to disable it:

1. Delete DOD and AFM by upgrading your valvetrain with the necessary parts.

2. Get a tune and have AFM deactivated.

Or...without requiring modification:

3. Pull the shifter all the way back to M. You are now in Sport Mode. Next, hit the left paddle shifter, wait 2 seconds, hit the right paddle shifter, wait 2 seconds, and then hit the left paddle one more time. Left, right, left. Don't do it too fast or it won't work.

AFM will now be deactivated until you move your shifter to Reverse, Neutral, Drive, or Park. This is more like a quick band-aid rather than a solution. My advice is to cam it and have DOD and AFM gone altogether.

[rshelar]

Ditto... CAM IT.
Even a Stage 1 cam kit will include upgraded lifters, springs, and rods. You can retain VVT.
There is a Range module on eBay for $89


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[christianchevell]

Most noticeable for me when AFM kicked in was driving the l99 I owned; on the freeway when it switched over after acceleration to drive at a steady speed it made a noticeable sound change; it would also have after driving in 4 cylinder mode of DOD a delay when stepping on it in the surge of acceleration and a change in the sound of exhaust.

You can actively monitor the mileage its getting in real time with the DIC (drivers information center);and its not getting the average from great local short stop and go driving..... that's more like the good average of that, high way you should be in the 20's up; city...meh...... down to 12 ish mpg even at worst that's more of a built mileage though....all depends on how you keep out of the pedal.