AFM or active fuel management is a GM/Chevy technology meant to improve gas mileage. AFM works by deactivating half of the engines cylinders under certain circumstances to reduce fuel usage. It essentially turns your V8 engine into a V4 which saves fuel.
GM claims fuel improvements ranging from 5%-15% depending on the engine. So why would you want to delete AFM? Unfortunately, it causes a number of issues for the Vortec engine family. The 5.3, 6.0, and 6.2 vortec engines that are equipped with AFM are known to have lifter failure, oil life monitoring system issues, and excessive oil consumption.
The excessive oil consumption caused by active fuel management combined with defective oil monitoring systems has caused numerous Vortec owners to experience premature catastrophic engine failure. Additionally, it frequently causes lifter failure which isn’t a cheap repair option either.
To prevent any engine problems caused by AFM you can either delete or disable the system.
What Engines Have AFM?
AFM is equipped on various Vortec engines. However, you need to look into your specific engine code as AFM is not used in every single engine.
- 5.3 Vortec: LY5, LC9, LH6, LMG, LS4
- 6.0 Vortec: L76, L77, LFA, LZ1
- 6.2 Vortec: L94, L99
- 3.9 Vortec: LZ8
- 4.3L EcoTec3 engines
- 5.3L EcoTec3 engines
- 6.2L EcoTec3 engines
- 3.6L V6 LGX
- 3.0L V6 LGW
- 4.2L V8 LTA
How Does AFM Work?
The top of the cylinder block has a valley cover over it which is called the lifter oil manifold assembly (LOMA). All Gen IV Vortec engine blocks have AFM towers and oil passages built into them. On non-AFM vehicles, the valley cover is completely flat and the towers and oil passages aren’t used. AFM vehicles come equipped with a special valley cover that has solenoids, oil pressure senders, and electrical connectors in it.
Additionally, the lifters on AFM engines are different. Cylinders 1, 4, 6, and 7 have taller lifters with oil holes in them. These are the cylinders that will shut off when AFM is activated.
When engine load is low AFM is activated. When this happens the GM ECU sends a signal to the valley cover which then opens the solenoids. Oil then flows to the lifters with the oil holes which causes the plunger inside of the lifter to close. When the plunger closes the lifters collapse and therefore do touch the pushrods which keeps both the intake and exhaust valves closed.
When load increases the valley cover solenoids close cutting oil off from the lifters. As the existing oil in the lifters funnels out they begin to function properly again re-engaging all 8 cylinders.
Understanding how active fuel management works is important for understanding how to delete it.
Benefits of Deleting AFM
The primary benefit of deleting or disabling active fuel management is in preventing engine problems. However, there are a few additional benefits. First of all, the V8 power is always available when you need or want it. And secondly, your Chevy will sound like a V8 and not like a little V4 Honda.
- Reduced likelihood of lifter failure
- Stops excessive oil consumption
- Louder exhaust notes
- V8 power is always there when it’s needed
How To Delete or Disable AFM
There are two options to fix the AFM issues on Vortec engines. Option one is to disable the AFM system, and the second option is to completely delete it. As we discussed above, the AFM system has a number of unique parts including the valley or LOMA cover and lifters. Additionally, it also has a different camshaft, a special oil pressure relief valve, and a high-volume oil pump.
Deleting the AFM system requires replacing all of these special parts with standard non-AFM parts. As you can imagine, this requires a good bit of labor and is also quite a bit more expensive.
Disabling AFM simply adjusts the engines ECU so that it never activates AFM. It essentially prevents the valley cover solenoids from ever opening which ensures your Vortec engine always stays in V8 mode.
How to Disable Chevy AFM
Disabling active fuel management requires either reprogramming or tricking the ECU into staying in V8 mode. To do so, you will need an AFM Disabler device. This device simply plugs directly into the OBDII port and starts working immediately. If you ever want to turn it back on or don’t want to take it to the dealer with AFM disabled, simply remove the device.
We recommend the Range Technology disabler since it is the only device on the market that doesn’t reprogram your ECU. Reprogramming the ECU voids engine warranty which is why this option is the best for anyone who still has some factory warranty left. The Range device comes in a few different colors, the different colors mean nothing. They do light up and are noticeable under the dash so they provide a few options for people who want different colors illuminating from their footwells. If you find the colors annoying you can simply put some tape over the LEDs.
Recommended Disabler: Range Technology AFM Disabler
Replacing the high-volume oil pump with a standard oil pump is still a good idea if you only disable the system. The excess oil the high volume pump delivers can cause oil buildup on the cylinder walls which then causes cylinder wall burning or scoring. While this will usually take quite some time to occur, it’s not a bad idea to prevent future internal engine issues.
How to Delete AFM
Deleting AFM is a bit more of a pain since it requires replacement of all of the AFM components. We generally only recommend deleting the system if you have failed lifters and have to do all of the labor anyways to replace them. Deleting the system also requires you using a disabler device or a custom tune so again, only do this if you really have to.
Here is a short checklist of what needs to be done to completely delete active fuel management:
- Replace your camshaft with a non-AFM camshaft
- Swap out the AFM lifters for standard lifters
- Replace the valley cover with a flat, non-AFM valley cover
- Disable the AMF system with the Range Technology Disabler, or custom tune it out
- Plug the pressure relief valve in the oil pan
- Swap the high-volume oil pump for a standard oil pump
A few random notes to go along with this as well. If you want to use a disabler instead of a programmer to turn AFM off then you need to leave the solenoid wires connected. If you do this, you can keep the AFM valley cover as well which will reduce some costs compared to replacing it.
When you keep the high-volume oil pump it flows excess oil. This excess oil will then seep into the bottom of the cylinder walls and burn. This can cause cylinder wall scoring/burning and lead to various performance issues and potential future internal repairs.
6.0 and 6.2 Vortec AFM Delete Kit
Should I Disable or Delete AFM?
Unless you have failed lifters we recommend disabling AFM. Deleting AFM requires replacing a lot of parts, gaskets, etc. which makes it more expensive parts wise, but also requires a lot of labor which is expensive you aren’t DIY’ing the project.
Additionally, disabling AFM allows you to turn it back on whenever you want. This lets you maintain your factory warranty and allows you to reinstall it if anything goes wrong from it being disabled.
If you do have failed lifters you can simply replace the lifters and then install a disabling device. The only reason we mention deleting it is that it doesn’t require a whole lot of extra labor to do so if you have to get to and replace the lifters in the first place.
In both circumstances we recommend replacing the oil pump, but I guess I’ll mention that not a lot of people actually replace this unless they are completely deleting the system. If you are just disabling it, it’s up to you but not a bad idea anyways.
GM & Chevy AFM Delete Summary
AFM lifters are known to fail more frequently than non-AFM lifters. Additionally, the system leads to excessive oil consumption. The excessive oil consumption can lead to oil levels running low, pressure dropping, and various major components such as the timing chain failing. Overall, the AFM system is responsible for a lot of very expensive repairs.
To prevent spending big money on AFM related repairs, the best option is to simply delete or disable the AFM system. Not only is it a good thing to do for preventative maintenance, it also gives you a better exhaust sound and keeps your car in V8 mode at all times.
Disabling the system is the best way to go unless you are already replacing lifters and just want to get rid of the whole system. Disabling it is the cheapest option and allows you to retain your factory warranty whereas a delete kit will be more expensive and void any warranty.
The only mentionable downside to disabling AFM is the decreased gas mileage it causes. AFM reduces gas usage anywhere from 5%-15% so removing the system will result in worse MPG’s. However, the money you save from not experiencing costly AFM related repairs more than outweighs the very small increase in gas costs.
Have you had any issues with your AFM system? Let us know in the comments and whether or not you went for a disable or delete kit.
I have a 2011 Chevy 1500 5.3 4×4 the AFM very rarely engages snd when it does it only engages for a couple seconds snd then straight back into v& mode it’s actually making me use more gas and I’m using about 21/2 -3 quarts of oil between changes I was getting 18.5 mpg average it has dropped to 13.5 mpg I have changed plugs wires air filter but can’t get mileage back up and truck seems sluggish and just doesn’t have the power it did have. I can turn the stabilatrac off and it sounds and feels like a completely different truck but the next time I turn it off it doesn’t do anything and it has more power with it on it also when I turn it off the low end ain’t worth a flip but the midrange runs awesome don’t seem to have much power low end some times when it’s turned off but either on or off my mileage does not get better any help in this matter would be greatly appreciated
Mike Glenn says
Great helpful information i have a 2012 and a 5.3 V8 in my Silverado……I’m going to have my FMS shut off by a shop that can do it for $175.00 I’m not going to do the ALD plug in for a around $110.00…I also have that slight flutter at highway speeds But only for a few seconds as it switches between a V4 and a V8…But my power low and mid range seems ok.
Jess osborn says
I recently completely deleted the AFM system in 2013 Avl, installed new lifters. Springs, stage 2 cam, tuned on dyno & it’s pulling 282 HP to the wheels. It runs great, I Love it. Haven’t checked mileage yet.
But does it pass smog?
Stanley Perry says
I had completely deleted AFM system on 2008 chevrolet avalanche 5.3 everything new but when I start it up it crank and kill
I just disabled my afm in my 2011 Silverado when I bought it with 72,000 miles. I never replaced oil pump with a regular one, truck has 126,000 miles with zero issues.
DAVID MCPHEETERS says
2013 Chevy 1500 5.3. Can hear and feel when AFM kicks in and fairly certain its not acting properly. Kicks on way to soon and I feel only killing one cyl when it does. goes away when I accel. No missfires show on scanner. now to decide which deactivate system to buy
I have a 2018 Silverado High Country with the 5.3 ltr. It has only 47k miles on it. One day I noticed a ticking noise. I knew right away it was a failed lifter. I have a life time warranty thru the dealer. So I took it in and that’s in fact what it was along with a bent push rod. They replaced all the lifters on the right side, replaced the bent push rod and the VLOM (which was on backorder for 5 weeks). Now it runs like a champ. So I think the only way to turn off the AFM is to put it in low gear and upshift to gear level 7. So my question is, is it better to turn off the AFM especially during city driving, or leave it in D? On the interstate, if I have the AFM turned off, my RPMs go from 1500 to 2000 at 70 mph.
Allen Bettigole says
I owned a transmission shop for 35 years before I retired and was well aware of what AFM was doing to the engines and transmissions. In 2011 my partner and I purchased two new half ton Silverado’s and in 2021 with only 62k my converter clutch started to slip on hills causing a surging sensation. I had disabled AFM at about 58k but to late and that was a $4200 repair for the internal transmission updates including a transgo shift kit, converter updated clutch valve, a new 3rd clutch drum, (they crack) and a reman converter and a back half of the transfer case housing, (corroded and cracked in front of the rear output seal). The truck also took a new fuel pump the week before due to a rust hole and evap leak on it’s housing. My Range Technology disabler is installed 24-7 and should extend the life of the engine and transmission at this point however the salt used by the Ct dot will ruin any vehicle and they don’t care. One last comment, my neighbors Saab 9-7X just lost cylinder #4 last week due to lifter failure at 150k, yes it’s a 5.3 GM Engine.
Michael Rossetto says
I have a 2012 Suburban w/ a 5.3 and after changing the oil & filter, I now have a fairly loud lifter tick coming from #1 or #2 cylinder.
I was thinking that I need to do a crankcase cleanout, but now I’m wondering if I should do a AFM bypass instead?
About 177K currently – bought it used at 160K.
2015 Chevy 5.3 pickup. 85000 klm about 50000 miles on it. Noticed a ticking sound occasionally. I was in the USA took it to a dealer and they quoted me $4400.00 to fix this. I researched on line and bought a AFM disabler plugged it in . No problems so far. Don’t put a lot of miles on the truck yearly. Hoping to keep it for another year or two .
I currently have a 2017 GMC Sierra 1500 4.3 LV3 with AFM lifter failure that damaged the block. So I am trying to put the LV1 engine from a 2018 GMC Savanna 2500 with the 4.3 non AFM.
But not too much info on the swap. I think it should just bolt up and add a tuner correct?
Any info will be appreciated.
Robin Bocook says
I currently have a problem with my 2013 Yukon. It looks like I’m going to have a huge expense in fixing my vehicle. Is there any chance that this could be considered in a recall? My Yukon has low miles but had I known this could be an issue, I wouldn’t have bought it.
Jake Mayock says
Robin – unfortunately there aren’t any recalls here. What problems are you experiencing?
Have a 2007 Tahoe and as I am coming to a stop the truck stutters. Have had transmission replaces 2 times. This seems to be the cause. What causes this stutter?
Cw meekins says
Try adding 3oz mos2 t oil additive to Trans. Oil. If this doesn’t help after several days add 3 more oz-repeat etc
Have just had transmission rebuilt. Transmission mechanic feels the stutter is the AFM System. Bought used and 3 months after had transmission replaced. Just had that one rebuilt. Added torque converter & cooling system. 210,000 miles. Want this to last me a few more years. Sounds like the range disabled is the way to go???
Jake Mayock says
Dave – a disabler is the way to go for sure. Most on the market will work just fine, Range is just the primary name brand.
I need help 🙂
2011 CHEVY SUBURBAN 1500 ls
vin : 1GNSKHE31BR148880
5.3-L V-8 OHV
DOES HE HAVE AFM ?
Jake Mayock says
Hey Mike – yes, this engine will have AFM.
can i replace an lc9 engine with a lmg 5.3 on a 2013 suburban
Karolyn J. says
I have a 2013 Tahoe with 72,000 miles. I have installed a AFM disabler. Am I still at risk for engine failure? Would you recommend I sell it soon?
Jake Mayock says
Hey Karolyn – this should solve any issues with premature failure caused by the AFM system. It’s of course not an absolute guarantee, but I wouldn’t be concerned enough about reliability to consider selling it.
Jay Crisologo says
so this system mentioned to “disable”, will its tricking the ecu trigger an CEL?
i pulled the fuse thinking it a solution and it was until a code was given.
im going to check out this system mentioned.
Jake Mayock says
Jay – no CELs with a disabler device.
Great write up!!
I have a 2009 Silverado that I will be performing the physical delete on. Standard lifters, new valley cover, plugging the oil pressure valve on the pan, standard non DOD cam. My question is regarding the post swap tune.
I will be performing the work with my brother in Austin TX, and I know this was mentioned in the article but is it possible to simply install the range afm device as a temp while I drive back home to Hays, KS, after which I will use TSP’s mail order tuner service to permanently time it out? Thanks for all the great info and for taking my question!
Jake Mayock says
Juan – absolutely, the Range device is purely plug-and-play just unplug it and the truck won’t ever know it was even on there.
Charles Seefeldt says
I have 2020 1500 lt crew cab with an infotainment system failure. I tried fixing this myself as the damage was self inflicted. On the back of the system there are two connectors going to the LED screen one of which has 2 wires going to it (the connector has 8 pins only two are used). I need to know which two pins these wires go to. It’s either a pin on each side, meaning 1 and 8 or it’s one pin in meaning 2 and 7. I cut the connection now I have to make a new connection. I’ve purchased 2 infotainment systems from the dealer and they will not cover this under warranty. Possibly a new wiring harness which one do I need
Rob C. (Allentown, PA) says
I purchased a CPO 2017 Suburban LS about a year ago with ~70K on the clock..
Over the summer the transmission gave up the ghost and it was replaced under the CPO warranty.
Now at ~88K the vehicle was stricken with the dreaded lifter failure “dead misfire on cylinder 7” as related to the AFM and the dealer replaced the left side valve lifters.
Fingers crossed that everything is GTG now (but if not, “please let it fail within the next year.”).
My question is –
Would it be prudent to purchase an AFM disabler at this point to preserve the new lifters and maybe prevent the right side lifters from failing?
Not purchase the AFM disabler so if the right side is going to fail it will fail within the next year and the CPO warranty will cover it?
Thank you in advance!!
Rick T. says
Have a 2013 Suburban 1500 z-71 4Whl drive with tow package. Have had all AFM issues in article. At 100k miles, under warranty, dealer repaired 7th cylinder/ lifter issue. Now at 247k, most likely have another lifter issue. Suburban still in very good shape otherwise, therefore will probably install an AFM Delete kit. Use the vehicle to pull 14’x7’x7’ cargo trailer. Make 2000 mile round trips from TX to MidWest ~6 times per year, 5k-7k pound loads. Article suggest changing from high volume oil pump associated with AFM system, to standard pump. With trips and loads involved, should I really go to standard volume oil pump.? Thank You!
*PS: MPG with AFM has been historically terrible… Non-Tow: 14-15 MPG; Tow: 8-10 MPG.
Prior two Suburbans (1994, 2003) averaged 16-18 MPG, non-tow, non-AFM.
I have a 6.2 that the lifter stuck. I did the tap on the lifter trick and it unstuck. Can I just have the ECM reprogrammed to disable the AFM?
Jake Mayock says
David – absolutely, you can use a tuner like HPTuners to program it out if you don’t want to go the plug-and-play device route.
I have a 2015 Tahoe 5.3L L83 it is throwing the cylinder 6 misfire code and a random miss fire. Mechanic said the solenoid failed in the lifter oil valley manifold cover. Everything is back ordered and they are not being made. Will the range disabler still work or should the delete be done.
Jake Mayock says
A disabler should still work so long as there was no damage to the actual lifter itself.
I have a eAssist 2018 Silverado. To disable AFM, I use a Range most of the time or drive in L7. I would like to install a complete AFM delete kit but so far I have not found anyone that makes one for the eAssist. This is due to the programming required.
Has anyone heard of a AFM delete kit for eAssist 1500’s. Thank you for your time.
2018 tahoe, 130000kms, range disabler makes the truck go on beast mode.
V4 mode feels like 1.6l corolla rolling down the hill.
I didn’t buy a v8 to play hopscotch on v4
I have a 2018c5.3 Silverado. I normally just turn off the AFm by going up to 5th gear.
Does the “Range” device still allow the transmission to shift into 6th gear?
Jake Mayock says
Yepp you can still shift into 6th with any of these disable devices.