[stchman]

I used my Hypertech to disable AFM on my truck as an experiment. SO many folks are constantly talking about oil consumption, AFM makes for WORSE MPGs, etc., that I thought I would give it a try.

With AFM I get between 17.8-18.3 MPG Monday through Friday back and forth to work.

I disabled AFM last night and topped off the tank this morning for the drive.

I got 20.1 MPG driving to work, which is surprisingly slightly better than what I get with AFM on. Now I know weather, fuel blends, etc., have an impact on fuel economy as well, my driving back and forth to work at least takes the terrain out of the equation.

I will keep the forum posted.

At the very least, I don't have to hear the AFM turn on and off and hear it on my exhaust.

 

[ChevyBoy2009]

So were we right?

 

[stchman]

So were we right?

I'm not going to declare anything after only 25 miles. So far it looks promising.

 

[Sierraowner5.3]

something to bear in mind is the fact that the ECM relearns things as you drive, so as you get more miles on it should only get better.

at least for me, the sweet spot if running 60-65 with the cruise on. flat ground the truck returns 23 on the instant econ display, and lots of interstate driving seems to support that.

Alex

 

[stchman]

The absolute best I ever got on my route to work for the week was 18.8MPG. Not bad for a heavy truck, but if it can do better with disabling AFM, then I'll do it.

 

[ChevyBoy2009]

I cant wait to get my Diablo and see what kind of numbers my truck will get :glasses:

 

[ChevyFan]

You should chart it. Do a daily log and include the total miles, the MPG shown, weather conditions, etc.

 

[McClintoc]

For the most accurate results, go through several whole tanks with AFM off and then get back to us. Good luck with the experiment!

 

[mfleetwood]

Good thread topic...thanks for starting it!

 

[stchman]

Update, day 2.

I arrived at work with the DIC reporting AVG MPG of 19.1. I will report back tomorrow.

 

[GuyGene]

Sounds good. I've read good things about that Range thingamajig on other forums. It's not a tune, but just cuts AFM mess off.

 

[bazar01]

On my 2011, I get 20mpg on the highway on actual mileage and gas consumption based on full tank going 70 mph.
City, I just put it on M5 and get 18mpg going from 35-45 mph speed.

You think the Range programmer will give me additional benefit on mpg?

 

[phoebeisis]

You have no oil consumption problem-right?
Anyone disable it who has the oil consumption problem?

Why would it get better mpg with the AFM disabled?

 

[bazar01]

You have no oil consumption problem-right?
Anyone disable it who has the oil consumption problem?

Why would it get better mpg with the AFM disabled?

I don't have oil consumption or oil burning issues at all. I change my oil every 7500 miles and still on top mark.
My mpg seems right on line as advertized. For me I don't see any benefit to disable it unless the 4-cyl mode puts some strain on the engine or causes uneven wear when in 4-cyl mode. Time will tell.

 

[RayVoy]

I just returned from a trip of 1,000 miles, did some experimenting.

I found (and this is using the DIC, resetting for each test) that if I drove at 40 mph on a 2 lane, I averaged 24.6 mpg (about 100 miles). If I increased to 55 mph, I averaged 20.2 mpg (again, about 100 miles). Interstate driving at 70 -75 mph, I averaged 18.2 mph. AFM was on.

This was in Maine, a lot of hills.

 

[ChevyBoy2009]

Alot of things come to mind and thats why im going to disable it...

1.Oil consumption issue(rather have my oil in my motor and not in my intake/anywhere else)
2.Crappy exhaust sound when AFM is on(sounds like a 4 cylinder on steriods with it on)
3.Better MPG(suppose to get better with it off)
4.Trucks have 8 cylinders-rather use them all(if you want better MPG-GET A PRIUS!)
5.Who knows what stress AFM causes to the motor(heat issues,carbon build-up,etc)

So im going to delete it and see how it goes once my tuner arrives...:great:

 

[phoebeisis]

Chevyboy
Yeah I buy all that-except the MPG.
GM engineers too clever to do the AFM for nothing-

Hey-I do have a 2006 PRIUS-+ a 1998 Suburban-perfect combination really.
The suburban was just supposed to be a hurricane evacuation vehicle (1,2 tall dogs 4 cats )-new orleans suburb-didn't expect long trip reliability from 195,000 mile vehicle-I wanted get me 100 miles N reliability.
But it became obvious it was very reliable-with 20 mpg hy mpg.Yeah pleasant surprise.

the 96-99 Suburbans get 20 mpg hy-and are dirt cheap-$3000 or less
very reliable drivetrains easy to DIY repair replace parts
Maybe the last 5.7s were slightly more reliable than the 5.3s-
but the 5.3s rarely actually break-leave folks stranded.A qt per 500 miles would be annoying-but it wouldn't really inconvenience me-piss me off if I had spent $30,000-
I expect GM probably has solved the problem on current models-and offers retro fits that work-but they probably try the cheaper retro fits 1st-SOP for car corps.

If I had a 2007 2008 that had the problem-was out of warranty-I would do the AFM delete-worth a shot.

The AFM-doesn't really kick in in city driving, right? It is mainly used in low load hy-maybe under 65mph level hy-no head wind?
Yeah when does AFM kick in? Careful driving-you won't lose much mpg wise.

 

[bazar01]

The AFM-doesn't really kick in in city driving, right? It is mainly used in low load hy-maybe under 65mph level hy-no head wind?
Yeah when does AFM kick in? Careful driving-you won't lose much mpg wise.

NO.

On my 2011, on "D" or M6, when you are going 35-45 mph, AFM kicks in and out and very annoying. So I just put it on M5 and it stays on V8.

But when going >65mph, you won't even notice when the AFM kicks in and out on "D" or M6.

 

[phoebeisis]

So it kicks in at under 40 mph??

What is the annoying aspect-the sudden "ricer" sound- or does it give a rough shift feel-little shudder etc?
I could see how changing from a nice low V-8 grumble-to a 4 cylinder sound-would take some getting used to
"what happened to my motor"

 

[bazar01]

So it kicks in at under 40 mph??

What is the annoying aspect-the sudden "ricer" sound- or does it give a rough shift feel-little shudder etc?
I could see how changing from a nice low V-8 grumble-to a 4 cylinder sound-would take some getting used to
"what happened to my motor"

I really do not care about the exhaust note. It is when it changes from V4 to V8 when you feel the rpm jumps up because of the increased torque of the V8 it could be causing the torque converter to slip a little. Or maybe the TC goes out of lock up mode and the rpm jumps up. Sometimes, the tranny gets hanged up on a certain gear and it does not know here it is at and you can feel the jolt when it shifts. So I just put it on M5 gear and it stays on V8 mode on city driving with a lot of stop and go and slow speeds.