Black Bear Tune, Afm Off?

fast86gn · July 27, 2009

Im going on vacation so a good time to send Justin my ecm, tcm. I'm still on the fence about the afm being on or off. Please advise, my truck does see some highway, less than 50%. My work commute has a lot of hills. Not a true daily driver, rather drive Grand National in good weather. My wife does drive highway to work, she drives 30 miles each way to work on level highway, maybe 8 times a month. Total milage for a year maybe 8000 at most. Truck is nbs 07 crew ltz, 5.3. Any other notes I should send him in my notes about preferences. PM are ok if you dont want to put out there for everyone.

Thank you, Tom

66nova · July 27, 2009

Im going on vacation so a good time to send Justin my ecm, tcm. I'm still on the fence about the afm being on or off. Please advise, my truck does see some highway, less than 50%. My work commute has a lot of hills. Not a true daily driver, rather drive Grand National in good weather. My wife does drive highway to work, she drives 30 miles each way to work on level highway, maybe 8 times a month. Total milage for a year maybe 8000 at most. Truck is nbs 07 crew ltz, 5.3. Any other notes I should send him in my notes about preferences. PM are ok if you dont want to put out there for everyone.
Thank you, Tom

Does it bother you? If not then I say leave it. If it does then turn it off. Most that have turned it off see very little change in mpg. It really all depends on your driving style and environment.

cujo8 · July 27, 2009

From what I've read for others with AFM. they say it isn't very useful for a truck of this size, they say it spends more time in V8 mode or rather it is always switching to V8 mode, so they are really not getting the advantage of the AFM. If you do a lot of level highway driving I would say keep it active, otherwise turn it off and enjoy the V8 power and if you are conservative you can still enjoy good fuel economy. I have 5.3 HO V8 w/ a blackbear tune and I routinely get 20 MPG driving back and forth to work.

music · July 27, 2009

My recollection is that GM estimates AFM improving mpg by about 5%, which I'm assuming is for their "EPA test conditions". I doubt that anyone would notice that much difference--except in a controlled experiment--but I wouldn't disengage it unless it causes other problems. The improvement would be higher for mostly highway driving.

VMax2007 · July 27, 2009

AFM sucks, turn it off!

LawmanSS · July 27, 2009

AFM sucks, turn it off!

Couldn't have said it better myself!

Stex · July 27, 2009

AFM sucks, turn it off!

Couldn't have said it better myself!

Help me here, what did you not like about AFM? I may be missing something...

LawmanSS · July 27, 2009

After replacing the exhaust with an aftermarket system, the truck would drone, shake, and rattle when in V4 mode. It sounded and felt terrible. Not to mention that I don't do much highway driving with my truck, so whatever benefits can be reaped from the AFM system were lost on me. I really question the effectiveness of the system. I subscribe to the theory that it is a gimmick designed to make the EPA happy...at least when we're talking about trucks. I had mine disabled, I don't miss it, and my fuel economy hasn't changed.

georgecdisc · July 27, 2009

I feel highway driving is not a good reason to base you decision on. Driving cross country I periodically go into V4, but not for very long. This is at speeds of 75+ mph. It works better in the 45-55mph IMO, that is where the benefits will shine more. If you do a lot of highway driving, removing it will probably have little/no impact on mileage.

miande · July 27, 2009

My AFM works best at 50 mph. I have a 5 mile stretch of state highway that I drive several times a day and my AFM is active for the majority of that drive. At interstate speeds, it doesn't produce enough power to remain engaged for any significant time, - unless I tuck behind a semi and take advantage of their draft.

brims · July 27, 2009

AFM worked fine on my truck (as in no problems) before I got it tuned. After the tune I could feel AFM jamming in and out of V4 mode. A lot of people have had that before and/or after a tune. If you have anything like that, turn it off. If not, it's completely up to you. It does nothing on a truck.