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Problem with AFM On A 2008" GMC Sierra W/5.3 Liter

Discussion in 'Performance & Fuel' started by Wesley, May 24, 2014.

  1. Wesley

    Wesley New Member

    I just bought a 2008 gmc 1500 4x4 with 5.3 litre and was driving it home (440kms), not knowing the truck had AFM, I heard a sound like a solenoid turning on, then a noise from engine like clicking or knocking. Then noticed low oil pressure. I pulled over and turned it off and checked oil level and it was ok. started back up and pressure was normal and sound was gone till I got up to 100km/h and sound came back. I shifted from drive to 3rd and sound disappeared. is this the lifters or what. is this cause by the AFM?
  2. JimmyA

    JimmyA Member 1 Year 100 Posts

    If the sound went away when in V8 mode. Just purchase a tuner to turn off!
  3. squatchy

    squatchy Member 100 Posts

    More than likely its another afm victim, and you discovered on the ride home the reason it was gotten rid of. I hope you bought it from a dealer and not private party?
  4. Dctackett10

    Dctackett10 Member

    If I was you. I would get rid of the AFM before it causes you much problems. I have mine off in my 07 avalanche. Might of lost 1 mpg. But IMO. It's well worth it
  5. JimmyA

    JimmyA Member 1 Year 100 Posts

    I have a tuner for sale that can turn it off, plus a few more options! Send me a PM, we can make a good deal for you.
  6. dobey

    dobey Rockstar 3 Years 100 Posts

    Gotten rid of?

    - - - Updated - - -

    Are you certain it's the AFM that's the problem? Typically, it will not activate at that speed, as the air resistance and RPM at that speed in top gear mean the load is too high for the AFM to work reliably.

    Did you buy it from a dealer, or a private seller? Did the seller mention any problem with the AFM? If I were you, I'd return to the seller and have them repair it or give you your money back immediately, unless you bought the truck already aware of the issue. It sounds like you might be in Canada, as you are using kilometers. Do you have lemon laws to protect you there?

    Don't just turn it off with a tuner. If it's behaving as you said, you may already have mechanical damage anyway, and disabling it with a tuner won't fix the problem. It will just hide the issue until you have an unexpected critical failure down the road. The issue needs to be properly examined and repaired (and if you really want to get rid of AFM, properly removed).
  7. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    I think your right, he probably is in Canada. And, 100km/hr is around 65 mph, that is the speed that AFM will kick in.

    To the OP, I would try an oil change. One thing that AFM does not like is dirty oil. I would try two, or three short mileage oil changes and then go with a good quality synthetic.
  8. squatchy

    squatchy Member 100 Posts

    Yes [MENTION=40835]dobey[/MENTION], gotten rid of. What is there to question there?
  9. dobey

    dobey Rockstar 3 Years 100 Posts

    GM has not gotten rid of it at all. All Gen V SBC engines have AFM, as well as VVT and Direct Injection now. Even the manual transmission Corvette with the LT1 has it. Even the Z06 coming out soon has it. All the Ecotec3 trucks and SUVs have it.

    What you stated had implied that GM stopped implementing it in any engines, when they have in fact done the exact opposite, and making it more widely used, as they have been doing over the last 10 years.

    - - - Updated - - -

    Above about 40 MPH it seems to never kick in for me. With the DIC set to current MPG display, I've only ever seen it display V4 on local roads at lower speeds. On the highway, I've never seen it turn on in my truck.
  10. squatchy

    squatchy Member 100 Posts

    No, what I said implied that the truck he bought is an afm victim, and instead of having it fixed (probably outside of warranty) thats why the owner of that truck got rid of the truck. Idk how that could be misinterpreted the way you did.

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