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Another 5.3 with AFM bites the dust ~ Chevrolet Active Fuel Management Problems

Discussion in 'GM Powertrain' started by hblock72, Jan 19, 2013.

  1. ChevyBoy2009

    ChevyBoy2009 Rockstar 4 Years 500 Posts

    On the highway im getting 18-20 with what i have done...pulling my 30 foot camper im getting 13ish...so that i think is pretty good for pulling a 5500lb camper...i love chevy and i will always stick with GM
  2. JimmyA

    JimmyA Member 1 Year 100 Posts

    I think that they had 3 and mine was one! Lifter bleed, mine clattered after sitting over-nite! A new lifter kit, solved my issue.
  3. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    Right-forgot about that
  4. tigerwitha88

    tigerwitha88 New Member


    Was told in person by the service director and service tech at my dealership when I had the same procedure done on my truck that you just had done.
    Only fix is new pistons and rings, lower end rebuild pretty much. Feel free to search the internet and find someone that only had to do the new valve cover, pan baffle and cylinder cleaning and it fixed the problem.
  5. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    I'm still not sure of the WHY
    Why does this happen with the AFM motors?
    Oil only can get in the combustion chamber in 3 ways I think(assuming no intake manifold gasket oil leak to intake side)

    1) Rings not working right
    2)Valve guide seals not sealing
    3)Maybe PCV valve letting too much oil mist into intake-not sure that can happen

    So what is it??
    And if the "easy fix" doesn't work-why would new rings pistons etc work
    IF they are the same as the original rings pistons etc?

    I'm wondering if perhaps when a cylinder isn't combusting- you don't get a good ring seal- because combustion pressure usually pushes the rings outward-and forces a better seal-and scrapes the oil off better too??

    So WHY AFM?
    What do the mechanics service managers who have done the "BIG FIX" say is the problem??
    Tigerwith a88'S info seem to imply they are putting in rings with more outward spring.
  6. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Charlie: A lot of the issue with the AFM system losing oil has to do with individual cylinder and piston cooling, when a cylinder is shut down even for a few seconds it begins to cool, the piston and rings also cool but at different rates than the cylinder being the neighboring cylinders are still producing heat and transfering it via the block.
    GM engineers believe via this method the rings are allowing excessive oil loss due to the differing cooling rates.
    Under normal circumstances a cylinder, piston, and rings would cool at a much closer rate being that all cylinders would be not running/building heat, which in turn wouldnt be transferred to the non-running cylinder.
    Something engineers seemed to over look or just didnt care about was the old NorthStar 1st gen engines (late 70's and early 80's) were terrible about oil fouling the plugs. GM had a recall for them around 81/82 to put an anti fouling extension in the block for the plugs and to swap the factory plugs for a hotter version. A friends mom went through 2 engines on her 80 Sedan Deville before the vehicle was bought back by Caddilac. Those engines used the same cylinder shutdown theory being used now, technology has gotten better but obviously it has developed enough to defeat all the old gremlins.
  7. eaglesdis222

    eaglesdis222 New Member

    2009 chevy avalanche engine issues

    I have 2009 Avalanche LTZ with 90,000 miles on the vehicle and have lifters that just collapse. The dealer denied my warranty and said it had poor maintenance. I cant believe that they would do this when this is happening all over. I filed a complaint with GM and have not got any results. I paid another well qualified Mechanic to fix the issue and I'm currently thinking about filing a complaint with the state attorney general office. This is ridiculous that this problem is happening to a lot of people and they are not fixing the issue. I spent a lot of money on this truck. I will never buy chevy again and they should of let this company fail since they care more about numbers then customers. Also it took the dealer 3 days to tell me they were not covering the repair. Maybe if enough of us get together we can get them to admit that there is an issue.
  8. j cat

    j cat Rockstar 4 Years 1000 Posts

    good answer on this. gm failed big with this in the 80's.
  9. Cowpie

    Cowpie Member 1 Year 100 Posts


    I can believe that. With the 3 full shot glasses of oil and other contaminates that my PCV oil catch can captured in 6000 miles, I am sure glad I put it on my 2013 5.3L. That would explain how your intake was soaked in oil. I capture it before it makes it to the intake. Imagine that stuff caking on the intake valves. And it is common knowledge, that oil in the combustion chamber will reduce the octane rating of the fuel and possibly cause the ECM to revert to other settings to compensate for knock and that would be a bad thing for fuel mileage.

    Not stopping a simple problem can lead to more difficult problems.

    As opposed to doing reactive maintenance, I chose the proactive route with my 2013. I really was not aware of these AFM issues when I actually bought it, it was in doing more reading and searching online about the ride before picking it up after the dealer final touches that I came across all of this stuff. So, right out of the gate when I brought the pickup home, new, from the dealer, I shut down the AFM function on the engine and installed an oil catch can. I dumped the factory fill oil at 1190 miles, and filled with full synthetic.
  10. Pat10

    Pat10 New Member

    Great I just bought a 2008 with 70k miles on it. Doesn't seem to have any problems as of yet and had a clean carfax report.
    It replaced my 1999 suburban.

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