Active Fuel Management

[clevers3]

Has anyone disabled the AFM by just unplugging the VLOM and if so what were the results?

[redvett]

No and what the heck is "VLOM"?? Why would you want to reduce fuel mileage at $4+ a gallon?

 

Has anyone disabled the AFM by just unplugging the VLOM and if so what were the results?

[txab]

No and what the heck is "VLOM"?? Why would you want to reduce fuel mileage at $4+ a gallon?

+1

 

I always heard if you messed with your VLOM, you would go blind.

[07VMax]

i think the active fuel managment hurts mpgs, my new truck is a lot worse on fuel than any of the other trucks ive had. it is the 6.0 but its like 4-6 mpg worse than the 5.3's, plus it never stays in 4cyl mod longer than 20 sec and un locks the torque converter every time it changes which jumps the RPMs up 300 rpm each time and in turn causes the trans temp to rise

[8.1HD/ALLISON]

If you unplug it, yes it will disable it. Yes it will set a check engine light. It also could send truck into reduced power mode. Never tried it. I would get a program to disable the system if you are interested in doing so.

[700 sportsman]

Never heard of anyone unplugging it, but tuning it out will indeed increase fuel mileage 95% of the time. My dad say between 1-2 mpg increase, the only time I can see a possibility of loosing mpg may be cruising on the high way if it were running 4 cyl the whole time.

[wurgs]

Disabled mine with a programmer and haven't noticed any decrease at all.

[kdixer]

I noticed a decrease in mpg when I disabled AFM for testing. But I suspect the results have more to do with terrain and speed. It is up and down hills around here and AFM kicks in alot on the downhill sections. So in my case it is good for an increase of about 1 to 1.5 mpg with it activated.

[clevers3]

The VLOM is the valve lifter oil manifold that is mounted under your intake manifold. It uses 4 solenoids to shut off the cylinders that are used for the active fuel management. As far as i can tell,there are no dtc codes listed for the afm. Also,does'nt the vehicle use the AFM to go into reduced power mode or does it use a different method?

[jimbrown1]

change the settings with an autocal or other programmer. I did that to mine so it only comes on above 60 mph instead of kicking on around town, which was getting annoying by the way. Much better now with the BB tune.

[clevers3]

I did unplug the AFM today,just to try it. The truck did go into reduced power mode and also the tranny did not shift correctly. I plugged it back in and the truck is back to normal. I guess i will have to get a programmer to disable the system. Any suggestions which programmers are best and why?

[jimbrown1]

I can only speak to the Blackbear Tune in this situation. I had a Superchips programmer on my 2005 Sierra which did not have AFM and it was too generic. Never really noticed much of a difference. With the BB tune, I was able to have Justin adjust shift points, turn off AFM below 60 mph, and leave the tow/haul button as is so I will not have to remove the tune when towing. There are some discussions on the Diablo programmer on this site, but I have not had any personal experience with them. Good luck.

[Sheep]

I had the AFM on my '11 Sierra rcsb 2wd 5.3L programmed out. Loss of fuel mileage is just not significant. Averaging just a tad under under 20mpg overall on an engine that only has 1600mi on it (6spd with 3.42 rear). When out on open roads (not interstates) usually drive 65-75mph. Do have a soft tonneau installed.

[4wd]

Or you could remove it physically! and avoid the hassle down the road..

 

I read some have replaced AFM lifters with LS7 lifters, change the guides and other parts....+ disabling it with a programmer, BB is popular here.