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Chevy Silverado and GMC Sierra Active Fuel Management Problems



  • wildcat82wildcat82 Posts: 3
    Mine isn't a rough idle problem; just a plume of smoke that only happens when cruising on the highway and I start to accelerate. Like I said before, I get no smoke any other times and the only plugs that foul are cylinders 1,7,4,and 6 which are the ones that shut down during AFM.
  • bspinz9bspinz9 Posts: 2
  • bspinz9bspinz9 Posts: 2
    hey guys i got a 08 silverado crew 5.3L Z71 ltz w/ 10k on it
    & im just wondering if anyone is having this same problem when putting the vehicle in reverse (from drive only) there is a significant 3-5 sec. delay basically leaving me stranded in the middle of the road on a 3 pointer
    i've been to the dealer they updated the flashdrives for motor & tranny etc..
    & still does the same thing & as usual its within the GM tolerance haha.
    tranny fluid levels are normal & i was just thinking if & i know this sounds out of this world ridiculous the afm has anything to do with it i wanna shut the afm off i think it just effects the total performance of the motor. I've been a long time gm owner & the 04' 5.3L is a monster thats why i stuck with the 5.3
    & besides that ticking noise after 60mph the truck is a great truck

    oh 1 more thing can the afm be shut off by a tuner & is the hypertech tuner worth it
    thanks in advance guys

    "i just think afm shouldn't be a option when buying a truck a truck is a truck for power & balls fuel management is for the 4bangers & buy american we gotta keep this country alive & trucks is the reason why "
  • obyoneobyone Posts: 8,054
    Save your money with the Hypertech. There are better tuners out there for the same price.
  • dyma82dyma82 Posts: 4
    Hi hunter9296, have you find anything new about this condition?

    I am having exactly the same issue with my 2007 Silverado 5.3 (Not Flex-Fuel).

    Thanks for your time.
  • Have the inside windshield piller trim replaced,The tck will go away for a while.It'l come back after a while.There should be tec service bulletine for this problem.
  • Soft lifters and valve springs is where the rough idle problem is,I bought a stethascope to find that there was a faint tick on my right bank,cold starts the tick or miss is more audible hold the peddle to the floor it gets louder.Then take it to your highly educated mechanic,let him tell you its piston slap knock,argue with him till he actually goes out to hear the problem.It took me 45 minutes to get my point across.The lunge problem is when the computor is in relearn mode it has a glich,for sure.
  • dyma82dyma82 Posts: 4
    I agree. Soft lifters could actually explain this problem (shaky idle), and reinforcing the theory is the fact that additionally to the shaky idle, my truck has always been affected by another issue, which is definitely caused by soft lifters (since it was 54 miles old). The other issue being: If I left my truck unused for more than two days, when I start it on the morning of the third day the engine sounds like a very bad diesel. Then little by little the lifters recharge and the sound goes away. It does it 3 times out 5 times I leave it unused for more than two days.

    I am trying to gather as much info as possible about this issue, its cause, and the solution, so that by the time I take it to the dealer I can “try” to get something useful out of them.
  • My 5.3 ltr 2008 Silverado runs great, but just doesn't cool effectively. The AFM seems smooth to me, and it makes good power for a 5.3 ltr engine. But long grades on the Freeway cause the temp to keep rising. I have to turn on the heater full blast, and slow down, to keep the gauge from continuing on up. I have had a few puzzling electrical problems, including stabilitrac system errors that are intermittent - wondering if the computer controls the electric fans ? and maybe that is the common root cause of my problem ? But the AFM works good - just not good gas mileage (around 12.6 to 13.2 mpg). Any hints from anyone ? Anyone else have cooling issues and low mileage ? (I have about 8000 miles on the truck now)
  • littlemaclittlemac Posts: 1
    dont know if you solved your problem or not but i had a similar problem with my 01 and it turned out to be the fan clutch. very easy to replace.
  • does anyone know if there is a way to disconnect the afm? I have 50,000 miles on my 07 with a 5.3ltr and have never gotten above 17 mpg. i got that in my 01 with a 5.3. id just as soon not have it if its not gonna help. at least i wouldnt have to listen to my exhaust go from a deep v8 growl to a 5 hp briggs and stratton.
  • Yep...No Problem. Said that in the title too. Jeeze...Get used to it cause it IS the future. Mine is a 2009 Z71 4x4 Crew Cab LTZ Silverado 5.3 with 6 speed auto and runs just fine but reading post on the internet will scare anybody. No Throttle problems, no Tranny problems, No engine problems, No paint problems, No electrical problems, No issue with shift points, No issue with AFM. Owned it 3 Months 9from new) and have about 13,000 miles on it now

    The Cons are:
    1. It's so quiet that I try to fall asleep on the highway.

    The Pros are:
    1. I could list at least 200 Pro's over my 2007 Silverado Classic 5.3 (non AFM) and more than half would be technical.

    So now you know. This truck is not lacking in any way. I don't really understand why so many people would buy a truck they didn't like or want, ya know? with AFM? Sell it and get a Ford. This truck is my Cadillac and I seriously doubt anybody is gonna improve on what GM has built here with a hack saw underneath it in the back yard.

    Just a clue how AFM works...very simple. The cyl's that de act have special lifters. What's so special? They have a locking pin, that's it. Those cyl are de act mode with less than 6% throttle or load...this is decided by several process in less than 20 milliseconds...they are pressurized in de act mode (4 cyl) controlled by solenoids in the oil galley under the intake manifold. If that system was to fail (de-pressurize) it would default to a V-8. It's simple and it works. On a 80 mile drive thru the hills and curves I was able to attain a high average once of 24.4mpg I get 23 often and have got 21 driving 70 mph.

    There are alot of parts in this motor that will fail before AFM does...Jeezes. I'm going to put 300,000 on mine then recheck it and see how it's doing then. I have bought 4 new GM vehicles in the last 3 years or so...1 of them had a minor quality control issue that was probably done by the transport driver. 1 was traded on this truck, the 2007 Silverado. It had 86,000 miles on it and zero parts replaced. just tires and oil.

    This won't be fun if we didn't get a little OT and throw in something about oil...I do have to admit I did develop the dreaded tick at start-up. I don't know what factory fill was and you don't either unless you put it in. That's why I drained that stuff the same week I bought it. Well I went with Mobil1 I have been running for years no problem and then after say 3000 miles, tick for 2 seconds at start-up every time...then started it sometimes even when warm which raised my brow. And NO it's NOT THE AFM...remember, the lifters have to be pressurized in order to collapse. Anyways, left that crap in there too long but switched out to The Castrol Edge USA made 5w-30 and about 1000 miles later presto! no more tick, at all. none. Mobil1 filter. I don't care what bobtheoilguy says this stuff works and it meets all current GM specs.
  • mp12mp12 Posts: 2
    "Those cyl are de act mode with less than 6% throttle or load..." 6%??? WOW! Thats seems a little sensitive in my book. No wonder my '09 is almost constantly changing "in & out" while in cruise on level highway. It was mentioned earlier that this feature can be deactivated. Anyone know where in the south Louisiana area this can be done? Just looking at my options.
  • garyj2garyj2 Posts: 2
    I have a 2007 sierra with the 5.3 afm. Bought new has 16400 miles. At 16000 miles one lifter has a cold start tick that last till almost complete warm up approx 5 minutes. After break in i used mobil one syn. With a mobil one filter. Took to the dealer they stated to add a additive i refused as no additive should be needed at 16000 miles. They said to change the oil filter to a gm filter which makes no sinse. So my question could synthetic oil be causing the problem even though i used it for 12000 miles changed every 5k or is it a lifter problem. Truck is embrassing to drive as it ticks really loud. Tick never began till i did the 16000 mile oil change, so i changed it again still with no results
  • obyoneobyone Posts: 8,054
    CSK is a known issue with these trucks. GM claims no long term harm will come of it. It is caused by one of two things. First is carbon build up on top of the cylinders, second is loose fitting pistons till they warm up.

    Do a search on CSK, cold start knock, and you'll find a ton of info out there.
  • garyj2garyj2 Posts: 2
    its not piston slap or carbon. its definetly a lifter. is anyone else having lifter noise.
  • I have a 2008 Avalanche 5.3ltr with active fuel management. Switched to Castrol Syntec oil. Bought the truck brand new off the lot, with a "shimmy", thought it was a characteristic of that kind of motor. Well 12,000 miles later check engine light and stabilitrac and traction control service messages started to display. Brought her in, and found a cracked spark plug in cyl 1. Seemed to running great until another 10,000 miles passed. Truck had same symptoms. Come to find out another cracked plug in cyl 1. Now 1 year later (jan 20, 2010) and an additional 10,000 miles from the first time it went in, Having check engine lights and stabilitrac and traction control service messages displayed, Truck is being looked at by the regional engineer, as the dealership has no idea what is wrong with this motor and "never seen these problems".... As others have stated if it is not run for a day or 2, truck has a nasty tic until it warms up. GM will be contacting me Tuesday with a verdict on the engine, if its a faulty block or top-end... Either way truck has 36000 miles on it and shouldn't be having these issues with cracking plugs.... Never did i hear of that happening... I think it may be a lemon :lemon: ...
  • My 2008 Silverado had issues with it jerking while going between 50 to 65MPH, had cyl #1 plug changed in January (it was cracked). Back in the shop today for the same problem. This time they are also replacing the plug wire also
  • My 2008 Silverado had issues with it jerking while going between 50 to 65MPH, had cyl #1 plug changed in January (it was cracked). Back in the shop today for the same problem. This time they are also replacing the plug wire also. Anyone else have this going on? Truck has 40K miles.
  • tafidtafid Posts: 12
    This is a problem I discussed some time ago. I have been round and round on this concern and no one (Dealer, Chevy Service, which is a joke, nor BBB Autoline).
    The last attempt three weeks ago, Chevy Service stopped responding. They say they investigated the concern thoroughly. Right.
    See what you think. They still call this normal.
    Add to this concern is that the truck feels like it shifts while I am stopped (about 25 seconds). :mad:

    The engine speed increases while coming to or at an idle. The last time the vehicle was in to the dealer, Ed Rinke, the service manager looked into the problem and saw the issue that I am having first hand. He contacted Chevy Tech Service who asked the Rinke Chevy service manager to try the same test on other Silverado’s. The result was the same, increased engine speed. The Tech Service explained that it is a known problem with on calibration fix at this time
    I contacted customer service (case #71-566-017-460) where Andrew Okkema tried to assist me. He contacted Rinke Chevy who told Andrew there was nothing to do. Tech Assistance says it is normal. I do not think customers expect their vehicle to continue going when they step on the brake to stop. :mad:
  • obyoneobyone Posts: 8,054
    Is your truck under factory warranty? Have you documented all of your service attempts to repair this problem? Since it seems you're pretty much tried all the avenues avaiable for free perhaps it's time to look up a lemon law attorney.
  • trophy950trophy950 Posts: 1
    This is a problem with my 5.3 AFM. It started at 38000. Lucky for me (or not ) the dealer told me this was a common problem and the lifters would have to be changed out. Perhaps they were truthful with me since they know me and what I do for a living. I have ben a diesel and auto mechanic for over 20 yrs. The first service writer tried to blow off the noise but the service manager quickly took over. Bottom line is GM dealers know of the problem and I was told that GM is paying the claims quick,fast and in a hurry to try to keep this under wraps
  • 2008 Silverado 5.3L - 35,000 miles. Damaged Camshaft and bad lifters. Why? Also door locks not working, tire pressure sensors gone nuts, stabilitrak and traction control issues, and of course rough running due to bad lifters and damaged camshaft. the lifter issue started out at about 34,800 miles with a noisy lifter tapping at startup that would go away after a few minutes. Oh yeah, it shifts rough too.
  • obyoneobyone Posts: 8,054
    Time to trade it for a 2011 model before it loses it's value.
  • gmcustsvcgmcustsvc Posts: 4,252
    Hello Pookadog,
    I apologize that you are having concerns with your vehicle. Are you currently working with your dealership to resolve the issues? Thank you,
    Mariah GM Customer Service
  • tafidtafid Posts: 12
    It is great to see GM actually reading and responding to concerns on this forum.
    I must say, however, I have issues that are now falling on deaf ears that GM Customer Service calls normal. I have been to the dealer multiple times, just recently last week, with the same result. So, to ask if he has been working with the dealer to resolve the issue means nothing.
    I will post my concerns again as a continued update to a posting awhile ago.
    See '2007 Silverado Engine Surge'
  • tafidtafid Posts: 12
    I am back to report on this on-going issue. The description below will inform you of the basic compliant. The Dealer contacted Chevy Techs and they say it is normal. Get this, it is normal for a vehicle to accelerate with your foot on the brake. It is OK for your vehicle's engine to surge up to 1000 rpm when you ease your foot off the brake.
    And last week when I asked for a more technical answer, they said the Chevy Techs says the AFM is shifting from 4 to 8 cylinder, even with the vehicle at 1 mph or after it stops. Now what? I tried "Chevy Customer Service" but because I will not settle they have simply ignored me. I have copies of the emails as well as all attempts to address this issue.

    RPM/Engine Surge:
    When easing to a stop or after stopping and slowly rolling (by easing off brake, no throttle apply) into my garage, the engine speed will increase surging the vehicle forward. It does not matter if the engine is cold or warm, nor driving for one minute or one hour. The engine speed will increase up to ~1000 rpm or more. The engine speed will surge and slowly come down to ~600 rpm in less than 15 seconds. This problem does not occur all the time, but I can bet on it happening each time I drive.
  • gmcustsvcgmcustsvc Posts: 4,252
    Hello Tafid,
    I apologize that you have a concern with your vehicle. Have you tried going to another dealership for a second opinion? Thank you,
    Mariah GM Customer Service
  • tafidtafid Posts: 12
    No, I will see if that works.
    Now, if another dealership see the problem, just as the original dealership, they will call customer service tech and get the same response. But, I will see if it does not cost me.
  • I posted back when I owned a 07 new body style silverado.That the afm was not working for 17,000,bad economy and performance.Truck started knocking and had to argue with world class gm mechanic for 45 min. Then he went out and listened to the lifter tapping as I explained to him before.After he replaced the lifters,plug wires and reprogrammed the computor,I began getting 20 to 24 mpg.BUT then the truck began its lunge problem,same issue as other posts.I put up with it long enough to trade it off.IMO the lifters are soft and need to be replaced with an after market brand.The lunge problem is more than likely a computer relearn glitch.The next oil change have the garage hit it with the relearn mode.see if it helps.
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