Active Fuel Management - Page 3

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Thread: Active Fuel Management

  1. #31
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    Re: Active Fuel Management

    I've checked a few aftermarket products but they run from $250 - $500 and will void the warranty. I AM ON A CRUSADE FOR GM TO FIX!

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  3. #32
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    Re: Active Fuel Management

    Superchips my friend Superchips.
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    Re: Active Fuel Management

    Will superchips de-activate the AFM??? or just give the AFM better performance? I want the AFM GOOOOOOONE!

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    Re: Active Fuel Management

    I have a 2008 sierra 5.3 with afm and I havn't had any problems but I did chang my exaust to magnaflow duals and it sound fine in v8 mode, but when cruising for awhile and v4 mode kicks in it sound very poopy basically like a four banger with duals. It can be kind of annoying on a long trip

  6. #35
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    Re: Active Fuel Management

    I have a 2008 Impala 2LT with the AFM 3900. It idles and runs perfectly. But I can instantly tell when it is in AFM mode. The engine has a slight shuddering sound that can be heard and felt almost as if something was out of balance. My car has 44K miles and I have driven other 07-08 Impalas with this same engine with lower miles that are hard to tell when in 3 cylinder mode. I'm wondering if normal engine wear, degredation of the plugs/wires, carbon etc will affect the operation of 3 cylinder mode because it would seem to me that this engine would have to be in tip top tune to get away with running smooth in 3 cylinder operation. I also notice that when caught up in 3 cylinder mode if I need a sudden burst of power there is a slight hesitation before the power comes on. I have yet to determine if this is caused by AFM or a faulty drive by wire unit. My buddy is going to hook up his scanner that monitors every function and see if there is something that can be traced.

  7. #36
    4.4 Liter Supercharged Northstar Wolfman01's Avatar
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    Re: Active Fuel Management

    I have the AFM engine, and love it. I've had no issues with it at all. Like Ponchoman, I can also tell when it is in V3 mode at lower speeds. It sounds like it's lugging a bit with just a tiny little bit of a sensation of the individual cylinders firing. It's not annoying to me, just noticeable. I can return crazy fuel economy numbers on pump gas on the highway. Just look at my sig.
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  8. #37
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    Thumbs up Re: Active Fuel Management

    Quote Originally Posted by ZZ71 View Post
    I got a 2008 GMC Sierra SLT E. Cab Z71 with 11,000 miles and have an ongoing problem with AFM for the last few months. My truck vibrates/shudders when its in V4 mode. Dealer people and I both drove an identical truck and it did not do what mine is doing.

    They found NO codes set or anything wrong. A search found a TSB relating to a check ball in the trans that sticks and will cause a harsh TCC lockup and vibration when in A4 mode is so equipped (2005-2008 trans).

    Whenever the V4 mode engages at lower speeds (whenever you let of gas at less than 40mph) and you have to maintain constant speed, the engine vibrates (or shudders as I call it) it does not switch to V8 mode right away, you have to give it more gas to make it switch and then you risk the chance of rear ending someone in close traffic. Kind of like with a carb where the accelerator pump was faulty and you stepped on the gas and nothing happened but then suddenly it went.

    The SM is calling in to GM tech line today tp see if they can find a solution.

    Dealer will not disable AFM but Wester's will for $595.

    Btw - All the talk about AFM being good for mpg, I am only getting in the mid 16's with this, best on the highway is 18.1. I never speed or hotrod, rarely drive over 65mph. My 2004 got this mpg so all those who claim over 20, I don't see it with my truck. My truck was built in June of 2007.



    I feel like you took the words right out of my mouth. I have been describing this crappy system exactly the same as you have with the vibrating and shuddering as if it is a carb with a bad accelerater pump. What more have you found out on this problem, if anything, since you posted this? What is the deal with "Websters" that you mentioned above for $595? I am to the point where I will pay just about anything to get this faulty system turned off/de-activated. Let me know if you have more---Please.

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    Re: Active Fuel Management

    I am with you-----------Every time I take my vehicle into the shop for any type of warranty repair I make it a point to have them try and repair this crappy AFM system. It sucks.

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    Re: Active Fuel Management

    Quote Originally Posted by ggcurtis View Post
    I can not believe what I'm hearing, I have a 2007 silverado that has been in the shop 3 times due to what feels like a misfire but no check engine light. Had the service manager drive and he said we had a problem but when the head mechanic connected to the ECM and drove it down the road with me he showed me that tremendous jerk I was feeling was the cylinder activating. They have had several complants on this and have contacted GM engineers on this one due to all the vehicles having the updated software loaded.
    I have a 2009 with the 6.0 and 6 speed tow package and I have had this problem since day one, it now has about 4k mi. Even when hot, the engine sometimes shakes when stopped at a light. The dealer put injection cleaner in it because they couldn't find any other TSB, but it did not help. There's alot on the web on this and apparently GM can't/won't fix it. Apparently A PCM tune will but it voids your warranty, I'm told. It adds stress to the driveline by shutting down when letting off the throttle and stepping on it again...feels as if there's driveline slop but it's just poor engine performance. Sometimes causes bad shifts as well. Don't know what to do...this is my 5th new silverado since '99; I love 'em but this might end it. Any good techs out there with a solution?

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    Re: Active Fuel Management

    Armydude... get a diablosport Predator (model U7194) and be done with the AFM/DOD for good! You can turn it off/disable it completely - plus, you'll gain 15-20hp/tq with their performance tune to boot! (even more giddy-up once you get your fueling dialed in, or even get a custom tune!!)

    I've had it turned off/disabled in my monte for over 3 year now, and no issues since...

    AND, my mileage actually went UP without it....
    Last edited by 06MonteSS; 11-03-2009 at 03:23 PM.

  12. #41
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    Re: Active Fuel Management

    I have a 2008 Grand Prix GXP with the 5.3 v8 and I it's great. It gets better fuel economy on the highway than the old supercharged 3800 I had in my previous grand prix. If you like to use the pedal in town you will feel in in your wallet. When you put it to the floor you get all 8 cylinders right now and it's a blast. Of course when you're using all that power you're using more gas, which is a fair trade in my opinion.
    It has not given any problems the 6 months I've owned it. My brother is also a certified GM mechanic and he says the active fuel management is a good system.
    I would definitely recommend buying one of these 5.3 equipped vehicles. I would make sure the car you're looking at has no signs of abuse however. Some people push these vehicles too hard and overheat them. Look at the engine and see if it's discolored like it was overheated. If it looks oxidized on a newer vehicle it's a sign it being overheated. Also look at the tires and brake rotors and make sure they're not burned off. If it has 20000 and has or needs new tires it's been beat. Keep in mind whoever owned it wanted the power, but make sure they didn't over abuse it. 18" tires on my grand prix run over a grand and rotors and brakes will run you $500, I'm sure the Montie uses the same sizes as the gran prix. It's normal to need replacements at the mid 30 to 40 thousand mile range. Anything earlier is abnormal.

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    Re: Active Fuel Management

    I have a 2008 silverado with AFM, getting a vibration when going from 4-8 cylinders, seems like a hesitation/vibration. VERY annoying when on the highway and the throttle opens up, especially when in cruise control! had a dealer say "it is normal", but I really think something is not tuned right here, going to another dealer tomorrow. I will keep you updated, BTW has anyone else known of this problem?

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    Unhappy Re: Active Fuel Management

    I just bought a 2010 Silverado with the 5.3L and a 6 spd automatic trans. My AFM won't stay in 4 cyl for any length of time. Its as if the truck doesn't have the power on 4 cyl to maintain the 63 mph I set the cruise control on. At this point, I'm getting worse mileage on this 2010 Silverado than I did on my 2006 Silverado that was the same truck, motor, etc. just a different year. Its really frustrating that they can't seem to get this stuff right. Any ideas from anyone on this or the 5 other issues I'm having would be greatly appreciated. I have posted at two other places about my issues with this thing if you want to check them out.

    2010 Silverado with numerous drivetrain complaints

    2010 Silverado has Rattles in both front doors when radio is in use.

  15. #44
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    Re: Active Fuel Management

    I just bought a 2011 Suburban with the AFM system and I don't like it. When it switches from V8 to V4 it sounds like and gives the feeling similar to a fuel filter stopping up. When it switches from V4 to V8 you can definitely tell the instant increase in power. To answer your question I have had no issues and no problems but don't like the feeling of it switching back and forth. If the dealer can deactivate the AFM system I will have it done.

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    Re: Active Fuel Management

    I was already to go out and buy a new Yukon when Active Fuel Management turned its ugly head. I love my 2005 Yukon that does not have Active Fuel Management. I cannot believe GM did not give buyers a choice.

    When I first heard about it, I went out to the web and researched active fuel management -- I was surprised that there are so many people having problems with it.

    I asked a few friends that bought new GM vehicles and it only got worse. Two different ones lost their engines due to Active Fuel Management. One at 30,000 miles and one at just over 50,000 miles. Both had trouble getting GM to fix the engines. On the one, he finally took it to a non-GM mechanic and was told that when Active Fuel Management is on, it releases the compression on the cylinders, but that compression is required for proper oil flow. The result was damage to the cylinders.

    After a lot of research I have yet to find anyone that is happy with Active Fuel Management. Their statements are all similar. It works good at first, but within a few thousand miles problems start showing up.

    I buy a new truck to not have problems.

    The only people to speak positive about it is the GM service department and they are basically part of marketing -- so it is there job to sell the positive.

    GM look around and give customers a choice.

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