LS Engines / Tech Articles

How to Delete or Disable Active Fuel Management (AFM) on GM Engines

 
LS Corvette engine - What is Active Fuel Management (AFM)?

(Image/Lethal Garage)

Active Fuel Management (AFM) is a trademarked General Motors technology that improves gas mileage by shutting down half of the cylinders under light-load conditions to reduce fuel consumption. It is also known as Displacement on Demand (DoD) or cylinder deactivation.

How Does AFM Affect Performance?

AFM is good for gas mileage and can be 5-7 percent more fuel-efficient under certain conditions.

So Why Turn it Off?

There are a few reasons:

  1. Many people find the four-cylinder sound annoying if their vehicle is equipped with a louder aftermarket exhaust.
  2. Some drivers want V8 power under their foot at all times.
  3. AFM lifters have a history of failing and oil consumption can be a problem.

How to Delete or Disable AFM on GM/Chevy Engines

There are two ways to disable or delete Active Fuel Management on your GM or Chevy Gen IV LS or LS-based Vortec engine—one is to install an AFM Disabler, and the second is to install an AFM Delete Kit. Here’s what you need to know:

1. Install an AFM Delete Kit

An AFM Delete Kit is recommended when an AFM lifter fails or when doing performance upgrades. It replaces the AFM components with standard parts.

When installing an AFM delete kit:

  • You MUST upgrade to a non-AFM camshaft because the cam lobes in the four AFM cylinders are ground differently. The engine will have 25 less pounds of compression in those four cylinders which can result in a misfire code.
  • You will need to turn off the AFM system using a computer programmer or custom tuning.
  • It’s a little more work, but it’s recommended that you plug the pressure relief valve in the oil pan.
  • It is also recommended that you switch to a standard-volume oil pump.

2. Install an AFM Disabler

An AFM Disabler is an electronic device that plugs into the OBD-II port, under the dashboard. It prevents the computer from switching over to four-cylinder mode. It’s a simple and effective way to turn off the AFM system and provides the added bonus of improving exhaust sound.

NOTE: A disabler device should ONLY be used if the valvetrain is in good working order.

Engines with AFM use a high-volume oil pump. When you eliminate the AFM system, the extra oil is no longer needed. Excess oil will be pushed out of the pressure relief valve into the oil pan. This will spray oil on the bottom of the cylinder walls which can cause oil burning, especially in high-rpm engines.

Which Option is Best—a Disabler or Delete Kit?

As long as a lifter hasn’t started to fail, you can get by with a less-expensive disabler as preventative maintenance. If a lifter has already started to fail, an AFM delete kit and non-AFM components are the way to go.

NOTE: If you were in a situation where you’ve installed the AFM delete kit, but don’t have access to a programmera disabler can still be a viable option. To do this, you need to leave the AFM solenoid pack connected to ensure no codes are thrown. You can reuse the original valley cover OR use a non-AFM valley cover, leave the harness connected, and tuck the solenoid pack away.

GM/Chevy Engines Factory-Equipped with AFM

Engine DisplacementRPO Code
5.3LLY5LC9LH6LMGLS4
6.0LL76L77LFALZ1
6.2LL94L99

How to Identify AFM Engine Components

The AFM system can be identified by its components. Look for the following:

1. Valley Cover

The AFM cover is called the Lifter Oil Manifold Assembly (LOMA). It’s ribbed with solenoids on the underside. It also has an electrical connector on the back. (Non-AFM engines have a smooth cover.)

LS - Lifter Oil Manifold Assembly (LOMA)

2. Engine Block

All Gen IV engine blocks have AFM towers and oil passages cast in. However, they are only functional on engines that used AFM.

LS - AFM Towers

3. Lifters

AFM engines use special lifters for cylinders 1, 4, 6, and 7. They are taller and have special oil holes.

LS - AFM lifters labeled

Engines with AFM also use a special camshaft, a high-volume oil pump, and a pressure relief valve in the oil pan.

How Active Fuel Management (AFM) Works

How Active Fuel Management (AFM) Works

(Image/GM Media)

When engine load is low:

  1. The computer sends a signal to the LOMA.
  2. The LOMA solenoids open.
  3. Oil flows to the special lifters through the AFM towers.
  4. The oil collapses the plunger inside the lifter.
  5. The collapsed lifters will not engage the pushrods and both valves remain closed.

Since no air can get in or out, four cylinders provide no power. The engine is running on only four cylinders.

The AFM cylinders are opposite of one another in the firing order. In four-cylinder mode, they act like air springs and allow for smooth operation.

As engine load increases:

  1. The computer sends a signal to the LOMA.
  2. The LOMA solenoids close.
  3. Oil bleeds off the lifters.
  4. The lifters return to normal operation.

All eight cylinders are now powering the engine.

NOTE: Some parts are not legal for use in California or other states with similar laws/regulations.

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81 Comments

  1. Pingback: LS3 Engine Upgrade Guide: Expert Advice for LS3 Mods to Maximize Performance - OnAllCylinders

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  3. What if the pressure relief valve is stuck “OPEN” and the oil pressure never gets up to where it needs to be? I’ve got about 6 to 8 psi of oil pressure after the engine gets warm and I have to stop at a traffic light. NOT GOOD!!

  4. Is the Pressure relief valve replaceable? Does the Pressure relief vavle ever go bad??

  5. GM tried this on cadillacs about 20 years ago and if memory serves me correctly it was a disaster

    • Trevin Martin says:

      368 CADI

    • I had privilege to work on some of that garbage they never did work . Anyway that horrible experiment was in the late 70’s early 80’s along with those converted Diesel engines…..those like the 8-6-4 nonsense were just terrible failures. All I can say is they now try this again and they are still having trouble…..when will they ever leave well enough alone

  6. I got as high as 23mpg on the highway in my ’89 K1500 with 350ci and a five speed manual. How about if they just let us have a manual transmission agains for fuel mileage?

  7. I have a ’08 6.0L out of a Silverado with an aftermarket oil pan that has no provision for a pressure relief valve. What can I expect with the AFM in place, or, with AFM disabled (not deleted)?

    • andy miller says:

      Disable the afm. Install ls3 valley cover. It has the orings in place, that seals the towers. The pressure relief in the pan opens at around 45psi to prevent over pressurization of the vlom solenoids. They have plastic casing, so you can imagine what will happen with aged plastic.

  8. If the 4th cylinder lifter has failed, would driving it damage the engine? Would you get enough power to drive at freeway speeds? Our 2013 yukon with 47k miles just failed. Having it fixed now, just curious Seems like a problematic design. Very expensive repair too!

    • Just had my afm lifter fail had to drive 500 more miles home on 7 cylinders in my 6.0 lt chev.
      Just pulled it down in the garage there was no other damage , luckily.

  9. GM should recall every vehicle with this terrible design flaw! Every one of these engine will have a lifter fail, this is a travesty!

    • I didn’t have lifters fail, I had the 4 cylinders 1,4,6,7 have such blow by that my choice was a valve and piston job or a new motor. I went with the new motor for the warranty. I only had 81k on the motor. My 2002 I had over 298K on it with no engine related issues. I will be installing the AFM deactivator tonight when I get hoe.

    • I have a 2013 1500 with the LC9. has 92,000 miles and was just told I have cam and lifter failure. $8500.00 fix. Looking to tear down myself.

    • I had a 2004 small block v8(4.8) 331,000 miles on the truck,it was the usual on the maintenance front axles,etc. Never did strand me on the side of the road way. September 2017, I got talked into trading for 2017 AFM this was a bad choice 5.3 engine. Only wish I’d did my homework, nothing but issues, from 14,000 miles it starts this motor noise,as if lifters at cold starts, let set up for 8 hrs same noise, this noise is on the right side of engine, it lasts 5 seconds but never heard this until we had this cold spell in the state low temperatures or it was just time for this to start? I have always loved Ford and Chevys , I don’t like this Vehicle not one bit, starring shaft has to be lubed or it whines, front A arms has done been replaced, tapping in motor, leaf springs has been lubed, retorqued, put completely new leaf springs back in on the rear , grease all down from rims to body of truck, you have to clean often,console shakes as if milk shakes in console which later they also put rubber bushings in front of coils of shocks ( front end) .You lock it down in 4×4 it s metal to metal , As of now I’m at 32,000 done gone threw all the arbitrator laws depending on how it goes? Pushing forward

  10. AFM sucks I’m paying for a truck that has broke down twice replace the cam and lifters and now it’s broke down again 105000 miles never heard of that in a 350 Chevrolet.

  11. put tran fluid in oil for a day till lifter became active, had to change the fouled plug. changed oil , its all working now, but want to disable this sorry system.

  12. Chris Kenney says:

    I did a delete on an 07 avalanche and no have no power, any thoughts on what might be going on? I have had some say that it is the valves and others say that it is the cat’s plugged. I don’t know where to being to look for the problem.

    • Chris, when you did your delete, did you also change the cam at the same time? If you left the original cam in, the AFM cylinders will be down about 25 lbs. of cranking pressure because the duration is longer on those cylinders to being with to offset the AFM lifter design. You may eventually see a check engine light from a misfire code and the ECM dialing everything back to protect your engine.

      One alternative is to swap in one of the larger 6.0 non-AFM truck cams. If you are using VVT, you could use the NAL-12612273 (L92) cam. If you don’t have VVT, you could use part number NAL-12561721 (LQ9) along with a 4-pole 3-bolt 2005 Corvette cam sprocket p/n NAL-12586481 to make it compatible with your ECM.

      If you swapped in a LS9 cam, you will find it makes good power at the very top, but it’s actually down from 5,000 rpm and lower where the truck spends the majority of its time. If that’s the case, Summit Racing has dedicated truck cams that will increase power through the range…bottom to top…but the meat of it is in the mid-range where your engine spends the most time. Give the folks in Summit Racing’s tech department a call (330-630-0240) and they can work on a solution for you.

    • Mike Sinnett says:

      I just did the delete and replaced the cam as well. Still have no power. I have no clue what to do now. I have already dropped a lot of money on this truck (08 suburban). Any help would be appreciated.

      • Hello Mike, if you don’t have any obvious signs like check engine lights etc., there are couple different possibilities. If you installed a factory truck cam, there shouldn’t be any particular reason for it to be down on power. We recommend taking the truck to a local chassis dyno tuner and talking with them about a reflash.

        They may be able to find some of those missing ponies. If you installed a performance cam intended for a car, it may be bleeding off some low end compression. A tuner can often fix that as well by giving it some more ignition advance in these regions.

        We’ve written some articles on the various Vortec engine upgrade paths, such as this one on LQ4 and LQ9–it discusses some of the better options for choosing a cam intended for use in a truck. You can search our site by engine code to find some of the upgrade articles we’ve published and more are on the way.

      • You also need the disabler installed in your obd connector. You will be placed in derate if the ECM does not see the correct resistance from the ATF intake.

    • Michael Badame says:

      Chris,

      I had the same issue and had to have the AFM information deleted from the computer and the car tuned.

  13. Keith Belair says:

    Question – i just bought a 2005 Saab 9-7 with 5.3 v8, (same as GMC envoy) which came with AFM, the car runs fine, so if i just install the OBDII electronic device, is it just as likely that my lifters will still go bad? Im a little confused on the problems too, I’m reading that the 2007 pick-ups with 5.3 really had bad oil consumption and plug fouling problems, but is the 2005 5.3 that came in the trailblazers, envoys, and sabb 9-7s the exact same design as these pick-ups and prone to the same failures? I guess they also went to aluminum blocks in 2007, not sure if that has anything to do with this issues… thanks for the advice!

    • Keith Belair says:

      I guess what I’m really trying to ask is,, are there any cons/disadvantages to installing the AFM delete Electronic module? You mentioned that it will shoot oil into the pan and on the cylinder walls possibly causing some oil consumption… So i have a running vehicle and my only concern is making it as reliable as possible, should I disable the AFM or not?? thank You so much!

      • Hello Keith, if your lifters are still in good shape, an AFM Disabler is a good idea. When they are locked into position, they won’t wear further and cause issues down the road.
        The vehicles affected were 2007 to Feb. 2011 AFM equipped engines (Aluminum or Iron block-L94, LZ1, L99, LC9, LH6, L76, LFA, LMG, and LY5). The secondary pressure relief in the back of the pan began to open at 55 psi and was completely open by 75 psi.
        In October of 2010, GM added a deflector (p/n NAL-12639759) to keep oil from being sprayed directly on the rear cylinders.
        Another option is to plug it entirely if the AFM is already removed. It uses a M14 x 1.5 thread plug like Dorman 65217. More information can be found in the GM TSB bulletin number 10-06-01-008g. It also mentions a valve cover replacement with revised PCV valve design.

        • Keith Belair says:

          Wow, thanks for the wisdom,, i checked my VIN Code (position #8, M=LH6) and my 2005 Saab 9-7x does have the LH6 motor with iron block,

          Are you sure it’s only 2007 & newer motors? I’ve read at many websites that the GMCs envoys, Chevys and saabs did start to come with AFM in 2005 with the LH6 motor,It says here it started in 2006 on the saabs, then the pick-ups got AFM in 2007.
          http://www.autoserviceprofessional.com/article/91652/ticking-gm-v8-lifters-and-dtc

          There is no light on my dash or anything that indicates the system is active or exists, so it’s very confusing, I’m still not sure if my vehicle has it or not. I can’t really tell from driving. I guess I might have to call a dealership or GM to get a definite answer on this one.

          I won’t bother with blocking the relief valve. a little burning oil is a minor thing, my main concern is avoiding a multi-thousand dollar repair needed to the motor.

          • Keith, we’re happy to help. The LH6 in 2005-06 was a little different than the one used in 2007-09, but both had AFM. As a side note, the early ones had a 24x reluctor and plastic chain guide (good) vs. the later ones with 58x and the spring loaded tensioner (not so good).
            There is a note in the TSB that states the bulletin doesn’t apply to the LH6 used in the Rainier, Trailblazer, and Envoy due to a different design oil pan and AFM relief valve. Because your Saab is mechanically similar to the Trailblazer, we’d suggest that you are correct and no changes need to be made to the relief valve.
            At this state, a disabler would probably do what you need it to do. You can monitor the oil level on your dipstick for 3,000 miles to determine if the deflector or plug would be needed, but chances are you won’t based on the TSB.

          • Keith Belair says:

            yep, you are 100% Right, I called a local saab shop and they filled me in, in 2005 the trailblazer and clones have DOD (displacement on demand), My next issue is getting extra ignition keys on the cheap. Apparently all passkey III keys are not the same,, I bought one that said for 2006 impala assuming all pk3 would be the same, and I could not get it programmed in my saab 9-7,, so how I’m waiting on ones that specially said for saab 9-7. hoping they will work. will feel like a jerk asking the clerk at lowes to cut them again.

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  15. My 2013 GMC Yukon XL 6.2L is currently having a failed lifer replaced. It is being covered under warranty since I only have 72,000 miles on it. Since it is not costing me anything out of pocket, I did not go with the Delete Kit (did not want to spend the money). Once I get it back, could I install the Disabler safely. I would rather stay a V8 full time than deal with AFM issues in the future.

    • Keith, sometimes they will only replace one lifter rather than the whole set–If that’s the case, another lifter can fail again pretty quickly.
      You are correct. Install the disabler when you get your Yukon back and it will remain in good working order.

  16. Mike Fasano says:

    Brian, I just purchased and installed a remanufactured L76 AFM engine for my 2007 Suburban. We were getting a code that the cam position sensor was not functioning properly. Changing the sensor didn’t help. As it turned out one of the cam bearings was failing and causing the cam to wobble (my guess) which messed up the AFM and probably some other stuff too. The engine had 200K miles. As we were installing the sensors prior to installation in the vehicle, we noticed that there was no fitting on the oil pan for the oil level sensor. I asked my local Chevy dealer, from whom I purchased the engine, to find out why the oil pan lacked the fitting. They learned that the oil level sensor was necessary and that we were supposed to have been advised that we needed to reuse the original oil pan. Fortunately, the old engine hadn’t been shipped back to the remanufacturer. When we removed the oil pan from the new block, we noticed a metal shield covering the bottom of the block. In other words, the crankshaft and bearings were not visible. Is this the shield you referred to in a past post? Side note, after 200 hundred miles of trouble free driving the transmission failed so we had to replace that too. I am leaning heavily on installing the AFM disabler. Thanks.

  17. Scott Perdue says:

    We recently purchased an 08 Suburban and noticed some shuddering around crusing speeds, usually 45-55mph and highway speeds around 75mph. Took it to a shop and they advised that it could be due to the AFM system not functioning properly. We are looking into the AFM Disabler option, but my question is- how do we know if a lifter is already bad or not? The car runs great apart from the shuddering at those speeds. Would it be fine to go ahead with the AFM Disabler? Or is the shuddering indicative of failed/failing lifters that need to be replaced before moving forward?

    • Shawn Campbell says:

      Brian, I have the same question as Scott. I also have 08 Burb, but have different symptoms (high oil consumption, blue exhaust smoke at start, and now a really rough start after sitting overnight). How do you know if the lifter has failed? I have no other engine problems and I’d like to fix the issue. Do you think I can still disable AFM?

      • Brian, I have a 2010 burb with the exact same symptoms and questions as Shawn… please help! Thanks.

        • If a shop pulled a DTC code P0300 and found AFM to be the issue, it may not be too late to try the disabler. It will show up as a misfire code in a cylinders 1,4,6, or 7. There is a filter screen under the oil pressure sender that may be clogged and not getting enough oil to supply the solenoids. This may show as low oil pressure or code P0521 or P0523 and is a relatively inexpensive fix as well.
          As the problem gets worse, you’ll hear a lifter tick and eventually you may see clearance between the pushrod and the rocker which will quickly destroy the cam. I’d try the disabler and the screen cleaning first and do the AFM delete if that doesn’t solve the problem.

  18. Eric Hansen says:

    Hi Brian,
    I bought a 2010 GMC Sierra 5.3L Truck in 2013 with 24K miles. Right now I have just over 77K miles with no lifter problems… Knock on wood… I am thinking of the AFM disabler. However I do have 7 year bumper to bumper warranty that covers this problem if I start to get lifter problems over the next 2 years.. On the other hand if get the AFM disabler installed I am pretty sure that I void the warranty from what I read on the policy. The problem I am facing is that I want to drive this vehicle for at lease another 77K and do not want to drive my vehicle with this AFM issue. What would you do if you were in my situation? Install the AFM disabler now or wait until my warranty just about to expire to get this AFM issue resolved?

    • That’s a tough call, if the warranty will cover it…I’d let it run out. As a side note, Range Technologies recommends removing the disabler between visits to the dealer as they will need to access the OBD-2 port.

  19. thanks brian love the info I’m thinking of buying a ford now

  20. Clinton Reed says:

    Hello. I have a 2011 Chevy Tahoe with the 5.3 Gen 4 LS (VIN Code 0) and I bought a CAM motion DOD/AFM delete kit, 3 bolt drop in CAM Motion stage 2 camshaft, VVT delete kit and finally a Diablo Predator 2 Premium for GM programmer. I was told that before I start the vehicle up I will need to have the AFM and VVT disabled in the ECU but that would require a custom tune from a tuner as the ECU cannot just be told that the AFM and the VVT is gone. I am trying to find out of this is true. Diablo says yes but they do not provide tunes. CAM motion says no just have to disable the AFM and VVT with a stock tune as the camshaft is not an aggressive camshaft but a drop in. There are no changes in the valves or the springs. I have also heard that the oil pump is to be changed and I have also heard that it does not matter. Very confusing stuff out there. Any advice that you could offer would be great. Thank you for your time.

    • A custom tune by a knowledgeable tuner with access to a chassis dyno will pay a lot of other dividends other on top of turning off afm and VVT. You will get codes thrown if the afm is physically removed without telling the ECM you did so. The tune is the best bang for the buck outside a cam swap anyway and what I’d recommend.
      The oil pump is high volume, but there are a lot of people that don’t change it and rely on the pressure valve to keep the volume manageable. The only problem is the extra spray on the cylinder models if a deflector isn’t used and this can show up as increased oil consumption.

  21. Robert Drum says:

    Have an ’06 Yukon with 5.3, original engine had bad knock, was told it was lifters so had them replaced. It was good for about 10 miles and started with same loud knock noise. Replaced the engine with remanufactured one and had the AFM turned off with a computer hooked to the ECU. Have misfire code and engine has what I would call a surge while driving. Is this due to the AFM being shut off? Didn’t really notice a loss in power other than the surging, (wondering if that’s the engine trying to switch between 4 and 8 cylinders).

    • With the AFM tuned off, it shouldn’t be trying to switch over to four cylinder mode. I don’ know what else would cause the surge, but I’d research the misfire code and see which cylinder is problematic. There may be an ignition related issue on that cylinder.

  22. I got a 09 Chevy I’ve had the 1 go out then the 7 about 2 weeks apart if I known what I know now I would’ve changed them all at once but now I have a misfire on cyl 4 but it came back in why are these lifters going out one at a time like this the 1st two that went out I was coming off the interstate an stabiltrack came on now the 4 misfired twice both times pullling out my driveway

    • Yes, always change all the lifters at once. What was happening to the first is slowly (or quickly in your case) happening to the others. Keeping the oil changes regular is important and it’s possible that a previous owner may not have been as diligent as you are.

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  24. Jeff Adkins says:

    I have a 2018 GMC with the Eassist and AFM
    Should I buy one to disable the V4 mode?
    Yeh truck has 5237 miles on it
    Oil 0w or 5w -20
    Thanks

  25. Brian, we have a 2007 Yukon Denali in our shop with a 6.2L v-8 that has suffered a lifter failure with camshaft damage. We have purchased a used low mileage 6.2L as that is all the extended warranty company would pay for. My tech just installed the engine, only to notice that he doesn’t have anything to plug the AFM solenoid pack into. The owner of the vehicle has apparently owned a few of these vehicles and stated that this vehicle doesn’t have AFM…never did? He claims that GM used the same engine whether it was or was not equipped with AFM in this year and model? I phoned the dealer and gave the VIN number, told it isn’t equipped with AFM. It had the AFM wiring & lifter cover installed with solenoid pack in the original engine, we even removed it to inspect. This replacement engine has the same camshaft sensor plug plug, 5 wire like the AFM would use, instead of the 3 wire. My concern is if I leave the non-AFM lifter cover in place & have nothing to plug the 5 pin AFM solenoid connector into, will I get a MIL? Logic says that it should not as the ECM isn’t programmed to use AFM, but will it see a lack of resistance from no solenoid pack plugged in? I could just transfer over the AFM lifter cover, but it is really nasty on the bottom side & I do not want to risk damaging this replacement engine if it is loaded with debris from the lifter & camshaft failure. Then again, it should have never been controlling those solenoids. Any thoughts or suggestions would be appreciated.

    • Billy, there is some interesting trivia here on the L92. Per bulletin 10-06-01-0007b, 2007 L92 had first and 2nd design. The 1st design (built prior to April 1, 2006) was had afm components but wasn’t connected. The 2nd went with a conventional valvetrain. As you said, the ECM was never seeing the AFM so I think you’re good to go. Please report back if you have any issues, but I think you are in good shape.

      • Brian, thank you for the quick response. We chickened out though and just bolted the AFM solenoid plate onto the used engine. We figured we already had the intake manifold off to install the engine, why run the risk of MIL only to have to removed the intake manifold again without being paid. We did take it apart to check for metal possibly being trapped inside, it looked like brand new. We believe this confirmed that the AFM has never been operating in this vehicle. Thank you again for the response. 🙂

  26. Hi. Sylinder one lost compression on my 09 5,3. No movement on the rocker arms. Replaced all lifters. No it runs fine on sylinder one but not on 6 or 7!!! Pulled the inntake and replaced valleypan With all the solenoids. Did not help. Pulled right valve cover an rockers on syl 6 dont move. Well, they move a couple of times after startup thats all.Asume its the same on syl 7 on the other side.Disconected the Connector to the solenoids, no difference. Seems my oil pressure sensor is bad, are showing the same oil pressure at all times, even when it dosnt run.Dont know it that fault was there before i replaced the lifters. (Bought car 1 day before lifter died!) I asume low oil pressure cant make some of the DOD lifters to malfunction? All New lifters were from AC delco. Can they be faulty? Its not possible to install them wrong? They layed over night in engine oil before instalation. Thankfull for any ideeas!

    • Took the heads off again. On the AFM lifters that dosnt work i have installed them With the oil hole Down! Installed them again, all facing upwards, will know tomorrow if that was the solution.If this is the cause i cant beleve why they arnt build so that it is impossible to install them the wrong way in the plastic holder.And altso that there was no warning or installation advice With the New lifters.If these are the only lifters in the Whole world that must be in
      stalled in a certain way a warning wouldn be a bad idea…

      • OnAllCylinders says:

        Ketil, let us know what you find out. We’d recommend a call to our partners at Summit Racing. Their tech guys have seen it all and may have some thoughts on this as well. 330-630-0240.

  27. Hello,

    On June 4th you stated “The vehicles affected were 2007 to Feb. 2011 AFM equipped engines (Aluminum or Iron block-L94, LZ1, L99, LC9, LH6, L76, LFA, LMG, and LY5)” I am looking at purchasing a 2012 Tahoe with the LMG per the build sheet. 50,000 miles. Are you saying that I am in the “clear” by a year and issues fixed? My local mechanic suggested whatever I buy with an AFM he will send off the ECU to have the AFM flashed out. Thanks for your help.

  28. Kevin Penney says:

    I’m servicing a 2011 Chevrolet 5.3 with AFM. Truck has an active P0300 code and runs very rough. Found that all passenger side cylinders are not firing. Only running on drivers side cylinders. Driver reported this occurred suddenly while driving down the highway. Truck ran fine before that. Not sure which direction to go from here.

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  30. Brian, I repaired a 2012 GMC Yukon Denali as the AFM lifter on #4 I take failed. Everything else looked good. Replaced all lifters on passenger side as well as pushrods for even wear. Everything was fine for two weeks, ow customer complains s it same noise it made as before. What’s the next step? Replace the cam or do the delete kit?

    • There is a good chance that some of the driver’s side lifters decided to go. It does seem that when they start going…they go quickly.

      There is a chance the cam lobe was stressed and started to deteriorate. That might show up if you cut the filter and looked for debris in the pleats. But yes ultimately, it might be time for a cam and any AFM lifters that weren’t replaced. I’m always sorry to hear when people run into issues like these.

  31. 2015 SILVERADO 1500 4×4 crew cab with 5.3L engine:

    So two weeks ago with approx 70K miles, I had an odd noise when accelerating and then engine light flashing and riding rough. Took it to the dealer and was told I had a “collapsed lifter.” I had purchased an extended warranty when I bought the truck new. Glad I did. Covers me to 100K. They replaced all the lifters, said no other damage, problem lifters were on cylinders 6 and 7.

    Shame this happened. Love the truck. Have an intake and Borla exhaust. Don’t want to make a move on a new truck or jump to a 2500 yet.

    Open to suggestions about best course of action. Delete the AFM, buy a tuner/chip, take it to a performance place and get an actual “tune” done that fixes it, replace the AFM lifters with non AFM type, change other engine components with this……etc…..etc…..etc…???

    If buying a “tuner/chip” which works best for that truck/engine?

    Thanks for any input/suggestions.

    Respectfully,
    Jim

  32. Have a lifter problem on my 2010 5.3 Silverado. Happened once 1yr ago, truck was not used for a week and worked fine when i started it back up. Now the problems back, I have 180k miles on it now. Jusy 3 weeks ago I quit driving it because of the lifter, but it worked fine when i started it back up. No clue what to do. The lifter seems to recharge whenever the truck sits for some time.

  33. Hello! I’m considering just replacing the 5.3 ( should be LMG, 2007 YUKON ) with the L96 crate engine. Can you tell me what needs to be done with the VVT?

    If possible, will simply not using VVT provide a powerful,good running engine?

    Thanks in advance!

  34. Dean Davidson says:

    I have a 2007 Gmc Envoy Denali with LH6 cant find a good LH6 engine but I found a 2011 LC9 engine w 52000 miles will everything plug up or what am I getting into?

  35. Hello Brian, I just purchased a 2018 Silverado with a 5.3 AFM engine, I have 200 km on it. I traded in a 2004 4.8 L with 256000KM on it that ran like a clock and never gave me a problem. After reading these forums I’m a little concerned about my decision to stay with GM. Do you think it would be wise to put a AFM disabler on a brand new truck to avoid engine damage? Should I wait until the warranty runs out, or will that be too late to stop possible damage? Does the disabler prevent the engine damage in the first place?

    Thanks in advance!

  36. I bought a new 2017 Cadillac CTS back in January – 3.6L V6 with 8-speed trans. I love the car so far. I’ve been a Ford guy my whole life, so I was unaware of AFM until a recent trip where I did a lot of highway driving and happened to bring up the real-time mpg display, where I saw it switch between V6 and V4. I was getting ~ 30 mpg, so I love that. But after reading this thread, I’m a little concerned about the long-term reliability.

    Is this an issue only with GM SUVs and trucks, or does it include cars too?

    I only have ~ 5k miles on it, and it hasn’t been driven hard, so I’m assuming the lifters are fine. Given that, would you recommend buying one of the OBD-II devices to disable AFM? Is there any potential down-side to doing this – in other words, might this do more harm than good?

    Thanks!

  37. Gary keeling says:

    Buying a Silverado 6.2L. It’s a CA EMMISIONS TRUCK. Will this AFM DISABLER damage anything???. Friend will send to me from Arizona. Thank you. Gary

  38. Pingback: L59 5.3L Engine Upgrade Guide: Expert Advice for L59 Mods to Maximize Performance - OnAllCylinders

  39. Brian, I have been reading your article about the AFM. I had a 2007 Yukon XL 5.3 with the AFM. Traded it with 180K miles and did not experience any problems. In 2015, I purchased a new Tahoe with the AFM and two weeks ago with 71K miles on it, the engine light came on. I wear hearing aids, but I thought I heard more engine noises, but after checking the gas cap, the light went out for a week. It came back on last Wednesday starting with a flash. I called my service station and they told me to get it in ASAP. I did and they diagnosed it as being on Cylinder 3, not one of the cylinders that deactivates. Anyway, after some pushing and pulling I took it to the Dealer who sold it to me. They took the engine down today found so much damage inside they ordered a new engine from Detroit. My question is: do I install the electronic disabler on the new engine to avoid future issues?

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