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How To Increase Your MPG?

Discussion in 'Performance & Fuel' started by ippielb, Jul 12, 2009.

  1. stchman

    stchman New Member 1000 Posts

    I know other forum members will blast me, but don't disable AFM on the engine. AFM does actually increase gas mileage. I don't get why people on here dislike AFM, it is almost imperceptable when the engine switches from V8 to V4. I can hear an exhaust note change with my aftermarket Flowmaster muffler, but that and the DIC is the only way I even know the engine has switched.

    A lot of engineers that are a lot smarter than any of us designed AFM, and it works.

    On road trips, I routinely got 20-22 MPG in my 2008 Silverado with 20" tires. I only have ~1400 on my 2013 5.3L Silverado, but I am getting ~17 with combo city/hwy driving.

    I also do notice better MPG with K&N air filters and less restrictive exhaust.
  2. Pikey

    Pikey Moderator Staff Member ROTM Winner 1000 Posts

    I think that the issue is that some members amf systems are not working correctly. They complain of clunky shifting and very noticeable and frequent deactivation/reactivation of cylinders. There is a thread somewhere on this site with a few of those members commenting on their issues. A few have gotten in a new truck (same year/model) at the dealership and say that the amf is completely different then theirs and works seamlessly.
  3. stchman

    stchman New Member 1000 Posts

    The AFM in my 2008 works the same as the AFM in my 2013. I notice the same behavior.

    Some people are just more sensitive to slight differences than others.

    Hypertech MaxEnergy modules have an option to de-activate AFM if the user wants.
  4. dobey

    dobey Member


    And some people do actually have problems. Just because your truck didn't doesn't mean others don't either. DoD/AFM has been available in various production GM cars and trucks for almost 8 years now. A lot has changed over those 8 years. There have been plenty of documented problems, and many service bulletins and updates, to help deal with them.

    Yes it works for most people, but it's by no means perfect.
  5. Thank you for sharing your information on this, stchman.

    Michelle, GM Customer Service assisting Evan
  6. stchman

    stchman New Member 1000 Posts

    Problems with AFM must be few and far between, I know several people that have 5.3L engines (Tahoe, Yukon, Sierra), and they have remarked at how well the AFM works.
  7. dobey

    dobey Member

    For one, it's probably a fair bit better on the Gen IV engines (07+) than on the Gen III engines. Though I have seen several complaints about both. It is probably also significantly less noticeable in the large and heavy trucks than in the cars which weigh half as much, and make more power.

    And while I'm sure you do know several people with such 5.3 equipped trucks, I'm also sure it's probably less than 100, and even if not, surely less than the probably 10-15 million (I can't find hard sales numbers, so this is a rough guesstimate, and US-only, so likely a bit low as well) AFM equipped vehicles that have left the assembly line over the last 8 years. :)

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