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Username Post: Will the dealer turn off AFM?        (Topic#195593)
christopherlutz 
Contributor
Posts: 431

Loc: Flower Mound, Texas
Reg: 11-10-06
08-03-08 09:19 AM - Post#1491119    

Gang,

I know it's pretty easy to get rid of AFM aftermarket...just wondering if anyone has had the dealer turn theirs off?

I have a long 100k warranty that I don't want to void.
Lutzy

1965 C20 (completely dismantled)
2008 Chevy Silverado 1500 (5.3l V8)
2006 Honda Pilot EX


 
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BuckFeverZ71 
Newbie
Posts: 38
BuckFeverZ71
Age: 28
Loc: Wisconsin
Reg: 08-05-07
08-03-08 11:33 AM - Post#1491228    
    In response to christopherlutz

I can't imagine they'd disable it for ya.

Just give them a call if you want to know for sure...worst they'll do is say no.
'07 NNBS Silverado Z71

- 5.3L Vortec
- Custom Dual Exhaust
- Coverking Seat Covers
- Westin Sportsman Brush Guard
- 17x9 Helo Maxx 6's wrapped in Nitto TG's
- Diablo Predator w/ AFM Disabled


 
Bad Bowtie 
Valued Contributor
Posts: 4552
Bad Bowtie
Age: 42
Loc: TX
Reg: 07-04-03
08-04-08 08:29 AM - Post#1491922    
    In response to BuckFeverZ71

Then watch u like a hawk everytime u bring ur truck in for a warranty repair....
GMC. We are Professional Grade.

http://www.cardomain.com/id/2004VHO


 
stroker87 
Contributor
Posts: 798

Loc: Illinois
Reg: 05-01-07
08-04-08 10:39 AM - Post#1492019    
    In response to Bad Bowtie

christopherlutz, what would be the reason for turning it off?
87 Silverado SWB 1/2 ton 383 Stroker Holley Stealth, 950 Pro & Some Other Good Stuff Link


 
whiteZ 
Member
Posts: 196

Reg: 08-27-04
08-04-08 12:01 PM - Post#1492085    
    In response to stroker87

I can't see any reason for turning it off unless you have custom pipes that sound bad or you are an oil executive. The only thing it effects is your mpg at highway speeds. now if you are talking about torque management that is a whole nother ball of wax.

 
rbarrios 
Old as Dirt Member
Posts: 6223
rbarrios
Loc: West Covina,CA
Reg: 03-29-00
08-05-08 12:41 PM - Post#1492875    
    In response to whiteZ

curious to know too--- why turn it off?
2010 Traverse
2008 Buick Lucerne CXL
2007 Impala 3LT
2003 Trailblazer-152,500 miles
1970 Monte Carlo
1964 C20
1967 Nova


 
BuckFeverZ71 
Newbie
Posts: 38
BuckFeverZ71
Age: 28
Loc: Wisconsin
Reg: 08-05-07
08-05-08 03:10 PM - Post#1492983    
    In response to rbarrios

I turned mine off because I have aftermarket exhaust and it sounded like chit in V4 mode.

Plus, the truck is more enjoyable to drive since it doesn't cut in and out of V4 and V8 mode all the time...
'07 NNBS Silverado Z71

- 5.3L Vortec
- Custom Dual Exhaust
- Coverking Seat Covers
- Westin Sportsman Brush Guard
- 17x9 Helo Maxx 6's wrapped in Nitto TG's
- Diablo Predator w/ AFM Disabled


 
stroker87 
Contributor
Posts: 798

Loc: Illinois
Reg: 05-01-07
08-05-08 07:44 PM - Post#1493197    
    In response to BuckFeverZ71

how did you turn it off? gas milage go down?
87 Silverado SWB 1/2 ton 383 Stroker Holley Stealth, 950 Pro & Some Other Good Stuff Link


 
BuckFeverZ71 
Newbie
Posts: 38
BuckFeverZ71
Age: 28
Loc: Wisconsin
Reg: 08-05-07
08-06-08 03:12 PM - Post#1493723    
    In response to stroker87

Via the Predator

Gas mileage stayed virtually about the same. Nothing drastic enough to notice anyway.
'07 NNBS Silverado Z71

- 5.3L Vortec
- Custom Dual Exhaust
- Coverking Seat Covers
- Westin Sportsman Brush Guard
- 17x9 Helo Maxx 6's wrapped in Nitto TG's
- Diablo Predator w/ AFM Disabled


 
stroker87 
Contributor
Posts: 798

Loc: Illinois
Reg: 05-01-07
08-06-08 06:50 PM - Post#1493881    
    In response to BuckFeverZ71

O'well I just switched from the flaspaq to the edge I liked having always pluged in I town now and then and had the performance tune a few time when towing cause I forgot to bring the flashpaq

Edge dont have that option, but my suburban never sees v4 any ways, well I lied down hill if I lift my foot of the peddle it does
87 Silverado SWB 1/2 ton 383 Stroker Holley Stealth, 950 Pro & Some Other Good Stuff Link


 
BuckFeverZ71 
Newbie
Posts: 38
BuckFeverZ71
Age: 28
Loc: Wisconsin
Reg: 08-05-07
08-07-08 02:51 PM - Post#1494398    
    In response to stroker87

Yeah I was considering the Edge for awhile but after I received an email from them saying that they won't ever have the option to disable the AFM I got the Predator.

I would like having the dash display tho.

'07 NNBS Silverado Z71

- 5.3L Vortec
- Custom Dual Exhaust
- Coverking Seat Covers
- Westin Sportsman Brush Guard
- 17x9 Helo Maxx 6's wrapped in Nitto TG's
- Diablo Predator w/ AFM Disabled


 
christopherlutz 
Contributor
Posts: 431

Loc: Flower Mound, Texas
Reg: 11-10-06
08-15-08 11:14 AM - Post#1500088    
    In response to BuckFeverZ71

Hey Gang - I've been away a while....

As to the question: 'Why turn it off' - curiosity more than anything. My mileage is now about 16.5 - which is pretty crummy given the 20 highway rating and my relatively "grandpa" style driving.

I have friends that have all sorts of other trucks (chevy's w/ the smaller motor, toyota's, etc.) and they are gettign 18 mpg combined w/o AFM.

I have the 5.3AFM 3.42 gears and 20 inch wheels - if I can't get 18 with that combo there is something really wrong. I'm not even getting the same mileage as the guys with the smaller motor and 3.73 gears - so, I pay more and get less - big mistake in my book.

So - long story, longer....I was thinking that the 3.42s require more engine to move the truck forward and might be part of the reason I'm getting poor mileage - especially combined with the 20's.

I'll be back at the dealer in a week or two and will ask all sorts of questions.

As a final note (and to reinforce something I read above) - I really don't think it helps mileage...

Thoughts?

Lutzy

1965 C20 (completely dismantled)
2008 Chevy Silverado 1500 (5.3l V8)
2006 Honda Pilot EX


 
elcamino 
Valued Contributor
Posts: 4987
elcamino
Loc: Lake Superior-Michigan US...
Reg: 03-30-00
08-15-08 12:37 PM - Post#1500139    
    In response to christopherlutz

I think maybe the 20's are playing a part in the mpg.

They must be wider than the stock tires were, right? That would create more rolling resistance, friction and affect mpg. If they are heavier, that would burn more fuel. Wider tires always create drag.

I would take what others say about mpg with a grain of salt. Many will put a good spin on things to make it sound like its something it might not be. My 2008 has 9,200 miles and in those miles my avg. is 17.5 mpg, once I hit 19.7 on a 500 trip. I have changed nothing on the truck but different brand tires of the same size (1 oem tire went defective and I could get a new tire immediately) and changed the truck over to all synthetic lubricants. Maybe those lubes add up to 1.5 mpg but there is no way I can prove that. One thing I am sure of though, they don't detract from the mpg.

If you still have the oem tires, put them back on for some miles and then see if the tires are what is costing you mpg. I think they are myself.

A long time friend is a service advisor for a big local GM dealer. He told me the biggest complaint he gets is mpg. The salesmen, the advertising etc all hype 20 mpg and everyone expects to get that when in reality, few do. Driving conditions, weather, blending of fuel and driver habits all affect the mpg. If your mpg is within the range on the window sticker then thats normal. Also, I can't say for Texas but in Michigan they up the Ethanol blend in regular fuel from 10% to 15% and that means reduced mpg. State mandated 15% blend eff. May 2008 so all the liberals who invested in Ethanol have a market for their product.
Mike
2009 Cadillac CTS4 AWD Performance Sedan
2012 GMC Sierra AWD Denali 6.2L


 
whiteZ 
Member
Posts: 196

Reg: 08-27-04
08-20-08 06:35 AM - Post#1503475    
    In response to elcamino

that 20 mpg is for a 2WD reg cab with standard 245/65/16 tires.

all the silverado trucks get the same epa rating.

also if you changed your tire size and didn't recalibrate your speedo the calculations are off.

I'm getting about 16 average for a 4wd crew cab which is better than my 99 4wd ext cab got and I have close to 50 more HP better ride, quieter, etc etc

Far as I'm concerned these are awesome trucks-the only complaint I have is the thin sheet metal. i sold my 99 at 200K miles and I plan on passing my 07 down to my son when he turns 16 at about the same mileage.

 
whiteZ 
Member
Posts: 196

Reg: 08-27-04
08-20-08 06:37 AM - Post#1503477    
    In response to whiteZ

Oh yeah, i get 28-32 MPG hwy at 75 mpg in v4 drafting behind a fedex truck :)


 
wolfz23 
Forum Newbie
Posts: 95

Reg: 03-28-08
09-07-08 09:41 PM - Post#1517477    
    In response to whiteZ

the 20's are your problem... basic physics.

a larger wheel has more distance to travel to create 1 revoluton. resulting in your wheel will have to spin faster in order to accomplish the same as a smaller wheel

on the flip side, in linear transition, a smaller wheel will have to spin faster to cover the same distance in a straight line.

so.. drag, and resistance aside, the basic idea is the engin has to spin the wheel faster to creat 1 revolution. spinning the wheel faster means more RPM's which means more gas used.

The next concept is the gear ratio. The smaller the gear, the faster the engine has to spin in order to get same RPMs at the wheel.

so.. your small gears spinning faster, and your large wheel spinning faster BOTH force your engine to spin faster resutling in more gas being used.

more gas being used = less MPG.

Think like 10 speed bike, if the front gear is small, you have to pedal faster in order to make the back gear do 1 revolution. if you put a bigger tire on the back wheel, you will again have to increase pedal speed to make that wheel turn.

If you had a 4:11 rear end or ther 3.73, you would have more torque, resulting in your speed getting to say 45 mph faster than if you had the smaller gear.

somewhat confusing.. but the point is.. your big wheels are the first culprit, and the small gear is the 2nd.

Hope this helps

Matt



 
rbarrios 
Old as Dirt Member
Posts: 6223
rbarrios
Loc: West Covina,CA
Reg: 03-29-00
09-10-08 11:27 AM - Post#1519341    
    In response to wolfz23

also heard that the 3.42 will use slightly more gas in city driving.
but its great for highway.
2010 Traverse
2008 Buick Lucerne CXL
2007 Impala 3LT
2003 Trailblazer-152,500 miles
1970 Monte Carlo
1964 C20
1967 Nova


 
stricker76 
Frequent Contributor
Posts: 2370
stricker76
Loc: Ontario, Canada
Reg: 05-17-06
09-10-08 06:29 PM - Post#1519670    
    In response to wolfz23

  • elcamino Said:
I think maybe the 20's are playing a part in the mpg.

If you still have the oem tires, put them back on for some miles and then see if the tires are what is costing you mpg.



They could be factory 20's.


  • wolfz23 Said:
the 20's are your problem... basic physics.

a larger wheel has more distance to travel to create 1 revoluton. resulting in your wheel will have to spin faster in order to accomplish the same as a smaller wheel



The wheel has nothing to do with it, unless we are talking about the weight of the wheel. You could run a 15" rim and a 20" rim and get identical milage out of both as long as the tire height stays the same, and both combos weigh the same.

As long as the tire is the same height as the factory tires (if they arn't factory tires), i don't think the wheels are the problem. I have also seen arguments about the weight of the wheels and how 20" wheels move the weight further from the axle, but either way they arn't costing you 2.5 mpg. I went from 31x10.5x15's to 285/55/20's on my truck and never had enough difference to notice in mileage.

The gearing could have something to do with it, but i would more suspect driving habits. You'd be surprised how much it can affect mileage. My dad always gets over 20mpg in his suburban on roadtrips. I took it once, and in 5 tank fulls i never got over 18mpg and i don't think i was overly aggresive.

I also don't ever believe the factory rated mpg. Ever looked at the window stickers at a dealer. When my dad started looking last year i looked at a few pickups. The 4.8L regular cab long box and the 6.0L crewcab shortbox both showed the same exact ratings?!?! I'd like to see that!
2007 Avalanche LT
1998 C2500 Reg cab 6.5L
1973 Monte Carlo - On the chopping block
1995 C1500 - R.I.P

http://www.cardomain.com/id/stricker76


 
Bad Bowtie 
Valued Contributor
Posts: 4552
Bad Bowtie
Age: 42
Loc: TX
Reg: 07-04-03
09-11-08 09:38 AM - Post#1520097    
    In response to stricker76

Those MPG estimates on the window sticker are just that, an estimated MPG- AN AVERAGE MPG. If you look closer there is another set of MPG numbers below those two single MPG numbers. This is the RANGE of in town & on highway MPG one should expect from that particular vehicle.

GMC. We are Professional Grade.

http://www.cardomain.com/id/2004VHO


 
christopherlutz 
Contributor
Posts: 431

Loc: Flower Mound, Texas
Reg: 11-10-06
09-12-08 09:24 AM - Post#1520851    
    In response to Bad Bowtie

My 20's are indeed factory wheels and tires - part of the Texas Edition package I bought.

I wouldn't consider myself an aggressive driver either...but, I guess everything is relative. I never expected to get 20mpg...but was hoping for a 17mpg combined.

I'm not that far off from that. I saw a post in this thread about tuning - I may go that route. I don't think the computer is programmed specifically for this combo. My guess is - it's programmed for the far more common 3.73 combo.
Lutzy

1965 C20 (completely dismantled)
2008 Chevy Silverado 1500 (5.3l V8)
2006 Honda Pilot EX


 
BrianEsser 
BANNED
Posts: 7383

Age: 38
Loc: North Star, Ohio
Reg: 06-30-01
09-12-08 10:43 PM - Post#1521417    
    In response to christopherlutz

You can still get decent milage with 20" rims. I work for an aluminum wheel manufacturer and we are ramping up to make 19 and 20 inch wheels for Honda. We already make them for other manufacturers. Future plans call for 22" wheels for Honda.


 
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