GM Active Fuel Management Woes
April 3rd, 2013, 9:20 PM
#13
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Judging by the comment from stingray300, he didn't understand what happens when you keep both valves closed w/o fuel and spark in an engine.
I don't understand what the failure mode is that's caused by AFM. Since the lifter is collapsed, it's just sliding up and down unloaded in the bore. There is a ten minute limit on AFM operation to allow the engine temp. to equalize. I've never seen V4 mode for more than about 30 seconds tho.
I don't understand what the failure mode is that's caused by AFM. Since the lifter is collapsed, it's just sliding up and down unloaded in the bore. There is a ten minute limit on AFM operation to allow the engine temp. to equalize. I've never seen V4 mode for more than about 30 seconds tho.
July 16th, 2013, 8:49 PM
#14
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My personal research on the internet has observed "excessive oil consumption" in the 5.3 V8's from 2007-2011, and a hint of it in the 2012 5.3 V8. I do not trust GM to do what is right, but only to act in their own personal self interest as it "hits the bottom line". This will eventually result in a loss of market share...once everyone starts talking about it, and the news spreads across the USA and other countries.
What "new" vehicle would I buy? Definitely not a Chevy truck, although they look good! Unlikely a Ford truck, although most other people are buying them. Possibly a Dodge truck, but owning a 1977 Dodge Aspen "turned my stomach" against Chrysler products for life. My conscience would object to a foreign truck.
I don't really know!
August 18th, 2013, 9:38 PM
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AFM can be turned off via Tuner software like HPTuners. I had similar issue with an 09 1500 at 103k miles. I ended up swapping in a 6.0 from a 2500HD (no AFM, and added benefit of VVT).
August 19th, 2013, 9:50 AM
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Glad I'm not the only one having issues with the AFM. Here's my story. I bought a new 07 LTZ in June of 06, the first one that my local dealer got in. Nothing but beautiful, spectacular everything for 34,000 miles. Took my family to Florida once and Myrtle Beach several times, camping, pulling my 27 ft tagalong. Then one day, WHAM! The transmission breaks a sprag gear pulling away from a stop sign. No worries, GM towed it and my dealer had the tranny out, rebuilt, and back in three days later. Great service out of it for several years and a lot of miles. Religiously serviced, as it would always let me know when it wanted its oil changed. (I'll come back to that later!)
One day, about 130,000 miles in, it starts to rattle, bad, like broken valve spring bad. Needless to say, I am a little frustrated as now I am out of warranty. Long story short, number one intake lifter, an AFM lifter, was collapsed and stuck. Call the service writer for advice, and for a mere 2 grand they will be happy to replace the lifters and the camshaft. I say thank you, no, and go to town to get the parts to do it myself. On my way, I pray for help. I ask the man upstairs to fix my truck, but if he decides not to, I thank him for gifting me the ability to do it myself. So I stop by the dealer... Lifter, Head gaskets, intake gaskets, lifter cup, antifreeze, oil and filter, somewhere in the neighborhood of $400. Leave there, stop by NAPA for some cheap oil and filter, as I'm gonna try that first. An Agel of a man, dear old Mike behind the counter hears my sad story and advises me to try a can of seafoam first. So ifigure hey, what's another 11 bucks and take it home. Change the oil, put in fresh oil with the can of seafoam and let it run and rattle for an hour. Drain the oil, install my new GM filter and 6 fresh quarts.......rattle, rattle rattle. Frustrated, I shut it off and go inside for a drink of water and to let my wife know that I will be tearing into her Sub. Ten or so minutes later, I figure the best way is to go ahead and remove the hood so I will have plenty of room and light. I start the truck to move it to the center of my shop, and it is running just as smooth as when it was new. Needless to say, I was having me a hallelujah breakdown right there in the driveway. Since then, I no longer wait for the truck to email me with regard to oil life. It is changed every 3,000 miles, regardless of the oil life indicator. That rig is now approaching 170,000 miles and is still plugging right along. It has plenty of other issues, like right now it needs front shocks. Dealer says $1330.00, Headache Ball says Thank you, no. I will convert to Arnott's and buy the spring compressor myself.
One day, about 130,000 miles in, it starts to rattle, bad, like broken valve spring bad. Needless to say, I am a little frustrated as now I am out of warranty. Long story short, number one intake lifter, an AFM lifter, was collapsed and stuck. Call the service writer for advice, and for a mere 2 grand they will be happy to replace the lifters and the camshaft. I say thank you, no, and go to town to get the parts to do it myself. On my way, I pray for help. I ask the man upstairs to fix my truck, but if he decides not to, I thank him for gifting me the ability to do it myself. So I stop by the dealer... Lifter, Head gaskets, intake gaskets, lifter cup, antifreeze, oil and filter, somewhere in the neighborhood of $400. Leave there, stop by NAPA for some cheap oil and filter, as I'm gonna try that first. An Agel of a man, dear old Mike behind the counter hears my sad story and advises me to try a can of seafoam first. So ifigure hey, what's another 11 bucks and take it home. Change the oil, put in fresh oil with the can of seafoam and let it run and rattle for an hour. Drain the oil, install my new GM filter and 6 fresh quarts.......rattle, rattle rattle. Frustrated, I shut it off and go inside for a drink of water and to let my wife know that I will be tearing into her Sub. Ten or so minutes later, I figure the best way is to go ahead and remove the hood so I will have plenty of room and light. I start the truck to move it to the center of my shop, and it is running just as smooth as when it was new. Needless to say, I was having me a hallelujah breakdown right there in the driveway. Since then, I no longer wait for the truck to email me with regard to oil life. It is changed every 3,000 miles, regardless of the oil life indicator. That rig is now approaching 170,000 miles and is still plugging right along. It has plenty of other issues, like right now it needs front shocks. Dealer says $1330.00, Headache Ball says Thank you, no. I will convert to Arnott's and buy the spring compressor myself.
August 19th, 2013, 9:56 AM
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Nice to hear that positive story!
I'm curious, is there seeming to be any relation between the AFM lifter problems and type of oil used? I'm not trying to start a "what type do you use" thread, just wondering if more are found to have problems with conventional or synthetic oil.
As someone that just bought a 50,000 mile 2010 Tahoe LTZ, I'd like to hopefully get ahead of the curve on preventing AFM related problems if at all possible.
I'm curious, is there seeming to be any relation between the AFM lifter problems and type of oil used? I'm not trying to start a "what type do you use" thread, just wondering if more are found to have problems with conventional or synthetic oil.
As someone that just bought a 50,000 mile 2010 Tahoe LTZ, I'd like to hopefully get ahead of the curve on preventing AFM related problems if at all possible.
August 20th, 2013, 4:29 AM
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Dave, I too never like to get into the "my oil is better than your oil" discussion, but I have learned a few things over the years. Based on the evidence I saw in my truck's engine, I would lean more toward the oil change interval than type of oil. I have always used conventional 5w30, nut I always waited for the oil life indicator to tell me when to change it. Engine oil doesn't really break down or go bad, it gets contaminated. I think that waiting for the message to change the oil allowed the contaminant levels to build and form the crud that stopped up the oil passages in my lifter. Looking back, I probably should have converted it to synthetic oil from the beginning. I did that with my cavalier in 03, and I know have over 232,000 miles on it and it still runs like a champ.
Another thing I will add, is that I do not like GM's design for the PCV in that 5.3. It's built into the valve cover, and over $100 to replace. I don't think it allows enough ventilation, as I often find condensation in my oil cap and dipstick, to the point of it even being a bit rusty.
Another thing I will add, is that I do not like GM's design for the PCV in that 5.3. It's built into the valve cover, and over $100 to replace. I don't think it allows enough ventilation, as I often find condensation in my oil cap and dipstick, to the point of it even being a bit rusty.
August 20th, 2013, 7:34 AM
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So you are running synthetic and changing it every 3,000 mi? That's pretty extreme if that's what's required! As someone who drives 30,000 miles/year I'm used to either changing conventional in 4,000 miles or synthetic in 6,000, depending on vehicle.
You may be on to something though. If the oil passages in those collapsible lifters are really tiny, not only would crud possibly plug them up, but you might need an easier flowing, more persistent oil film to keep it lubricated. I'm just guessing, but your experience might make me think that way.
I've found over the years that most manufacturers problems get figured out by the owners and aftermarket that search for answers. I'm surprised there isn't a definitive "fix" for this problem given it's been talked about for 4-5 years now.
You may be on to something though. If the oil passages in those collapsible lifters are really tiny, not only would crud possibly plug them up, but you might need an easier flowing, more persistent oil film to keep it lubricated. I'm just guessing, but your experience might make me think that way.
I've found over the years that most manufacturers problems get figured out by the owners and aftermarket that search for answers. I'm surprised there isn't a definitive "fix" for this problem given it's been talked about for 4-5 years now.
August 21st, 2013, 5:08 AM
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No, sorry for the confusion. I run synthetic in my Cavalier, and change it every 10,000. (Crazy I know, but true) I run conventional in the Suburban because I am afraid of leaks on the 5.3. Synthetic oil is awesome, but it will find a leak in no time. But yeah, I am content to change the oil more often if it will prevent me from having to pull the head and replace a lifter. I can change a lot of oil for 2 grand.