2014+ AFM (Active Fuel Management)

[Dangelo]

2 minutes ago, CamGTP said:

It's just one less than the top gear in a 8 speed, the only real simple answer to that.

 

6 speed is 5th and 8 speed is 7th.

Well good to know, I’ve been putting it on M5 this whole time putting it on M5 won’t mess up anything will it ? I don’t know much about engines I’m a novice, I can build you a house just not an engine lol 

[CamGTP]

No. You just used more fuel running the rpms higher.

[Dangelo]

1 minute ago, CamGTP said:

No. You just used more fuel running the rpms higher.

Ahhh ok thank you sir I appreciate the info 

[Buckwild27]

7 hours ago, Dangelo said:

Ahhh ok thank you sir I appreciate the info 

You can just unplug the sensor on the brake booster hose to prevent it from going into v4 mode (this sensor is what tells the ECM it has enough vacuum to allow V4 mode) and you will be able to use all 8 gears. 

[KARNUT]

I’m just spitballing and wondering at the same time. With my 2014 I just bought a handheld and turned off the cylinder deactivation. Making it last longer that way is certainly debatable. I had the higher gear so it turned a little more RPMs at 70. I still got 22 MPG at 72. The wondering part is with the new trucks. If you get the highway geared truck and run the next lowest gear, 9th. How much does that affect fuel mileage much. The 6 million dollar question is does that really effect longevity by locking out cylinder deactivation. Those opinions will vary. You can’t really prove either way because there’s so many variables. If they worked like my Honda. On most of the time and you can’t tell but the light. I’d be totally for it. If it fails prematurely then I wouldn’t. 156K miles and counting. 

[Jay Ratliff]

On 12/11/2013 at 2:13 AM, DanielAcosta said:

For me it's a fun video game seeing how much time I can spend in V4. My best so far is accelerating from 15 all the way to 50 on just 4 cylinders. My instantaneous readout usually goes up about 20% when it changes from V8 to V4, so it does save some gas. With a small lift and 34" tires, 20mpg overall seems pretty good to me.

  Now I'm not picking on anybody here. Who could have known, right? But I almost spit tea on my screen when I just read this response from 2013.

[KARNUT]

8 hours ago, Jay Ratliff said:

  Now I'm not picking on anybody here. Who could have known, right? But I almost spit tea on my screen when I just read this response from 2013.

Why?

[MPJohnny5]

On 4/4/2023 at 11:07 PM, Tucker said:

 

We have 5 Silverado's 2016-18 in our farm fleet. The 2016 is a 6.2 it had a AFM collapsed lifter at 38k miles. AFM was turned off via tuner after powertrain warr, ran out. Still running today at 160k miles no further problems. 3- 2017's all 5.3's. One collapsed AFM lifter on the truck I drive @ 32k miles, now at 60k miles no more problems. Other 2 trucks  @ 70k & 77k miles no problems. The 2018 @ 90k miles no problems.

 

I use a Range V8 on the truck I drive as well as one other 17. All these trucks are serviced 4k mile intervals with Mobil 1 Dexos oil and AC filters. These trucks all see alot of short trip start stops. But do see some extended hwy. trips from time to time'

 

 

Did all of these trucks have the AFM disabled?

[Tucker]

On 3/17/2025 at 3:55 PM, MPJohnny5 said:

Did all of these trucks have the AFM disabled?

 The truck I drive had a Range V8 plugged in and it lost a lifter @32k. Truck is now at 83k no further problems. The 2016 6.2 is now over 200k miles no problems, had AFM turned off via tuner after warranty expired. The other 2017 with the Range has not had any failures.  The other 3 trucks still have the AFM active with zero problems, those trucks are from 90-110k mileage.

[Grumpy Bear]

185,000 on my 2015 with AFM active from day one. Spend as much time as I can in V4 mode. Ole girl sings like the Mormon Tabernacle Choir. I have spent literally less than $20 in non-routine maintenance parts. Then again I don't use 0W20 non-polar oil and I never let the bulk oil temperature exceed 210 F. Rarely 200 F. And I don't see what records I can set for longest oil change interval, loosest filter or dirtiest fuels.  

[customboss]

For those that are concerned or have dealt with AFM valvetrain metallurical driven failures consider this: 

 

 

[WuTang4Life]

On 12/9/2013 at 7:03 AM, Ron.s said:

Looking for a comparison on when AFM is active. On my 6.2 the v4 mode is active only at low speeds 45 or less and coasting. At idle it runs V8 mode, a big surprise as that's where a lot of fuel savings is available. The truck could easily pull higher speeds in V4 so what gives? Power is awesome and shifts seem about right but economy less than expected. I read that there was a top end oil problem a few months ago so wondering if GM adjusted AFM as a fix. I'm not real concerned about economy but why waste gas at idle. And yes I know the argument for bypassing AFM. Is this only my truck or other 6.2 and 5.3's similar? Trying to get educated before a dealer visit.

Ron

Dude, that's weird that your 6.2L only goes into V4 mode at low speeds! Most of the time, AFM is supposed to kick in when you're just cruising on the highway, not so much at idle. Yeah, GM has had some oil problems with these engines, so it's possible they tweaked the AFM to try and fix it, but it sounds like it's messing with your gas mileage. You're not alone, a lot of people complain about AFM, and plenty just get it bypassed.

[pixelmonkey]

question I haven't seen asked...

2016 Sierra 5.3

reprogrammed in july 2025 to disable AFM

 

noticed a tick in September 2025

October 2025, flashing CEL and p0304 and p050d

 

looking to replace the lifters, push rods, head gaskets...

 

Is a cam replacement required, if the cam is still good, and reprogramming has been completed?

my fear is with the oil pump bolt.

 

hopes are to use the stock AFM cam with non AFM lifters. 

[newdude]

17 minutes ago, pixelmonkey said:

question I haven't seen asked...

2016 Sierra 5.3

reprogrammed in july 2025 to disable AFM

 

noticed a tick in September 2025

October 2025, flashing CEL and p0304 and p050d

 

looking to replace the lifters, push rods, head gaskets...

 

Is a cam replacement required, if the cam is still good, and reprogramming has been completed?

my fear is with the oil pump bolt.

 

hopes are to use the stock AFM cam with non AFM lifters. 

 

 

You have change the cam to go to AFM delete.  Can't just throw non AFM lifters in all 16 bores and call it a day.  The lobe profiles are different on the 4 cylinders with AFM to accommodate the lifters.  You will have low/very low compression on those 4 cylinders if you just changed the lifters and kept the stock cam.  

 

If you are doing the full mechanical delete, change the oil pump as well as those can have the solenoid fail and you got to tear the whole front end of the engine apart again to change it if it does after doing the delete.  

[davester]

The tune may also be different between "disable" and "delete".