Less expensive AFM bypass that works

[Familyman2112]

I bought my 2011 Yukon Denali about four years ago with 82k on it. I liked almost everything about it, except I really disliked driving it on the highway. Up to 80 mph it was great, 81 and up was terrible. The vehicle would shudder a bit and it had a weird vibration. Slow down to 80 and all was good. I was suspecting suspension issues, but everything seems tight and operational, other than a missing sway bar link. After much research I kept coming across posts about the AFM causing the same issues. Not wanting to go the expensive tune route only to find out it didn’t fix the issue, I bought a relatively inexpensive bypass from Amazon. After driving over 500 miles on the highway yesterday, WOW, this thing works. It was such a smooth ride at 85-90 mph. I am amazed at how the AFM adversely effects the drivability of a vehicle, but until you get rid of it, you won’t be enjoying your luxury ride as much as possible. It’s pretty cool that outside of the cost and time of replacing 15 year old parts, I am enjoying my Yukon more than I did when I bought it.

Now that I have bypassed the AFM, what else would an actual tune do for me?

Amazon.com: AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L : Automotive

Buy AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

a.co

 

[Familyman2112]

Oops, fat finger syndrome! I hit enter before finishing my thought. Now that I know what it’s like without the AFM, what else would a tune do for me?

Amazon.com: AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L : Automotive

Buy AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

a.co

 

[j91z28d1]

spam

 

[Fless]

Oops, fat finger syndrome! I hit enter before finishing my thought. Now that I know what it’s like without the AFM, what else would a tune do for me?

Amazon.com: AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L : Automotive

Buy AFM/DFM Disabler Active Fuel Management disable Device Compatible with V6 & V8 GM Vehicles Fits for Chevy 5.3 Silverado (Chevy Tahoe GMC Sierra Yukon Cadillac Escalade etc) 3.6L 4.3L 5.3L 6.0L 6.2L: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

a.co

FYI You should have an "Edit" button at the bottom of your post -- usually that functionality lasts a few days, so you can go back and edit the post.

 

[Familyman2112]

spam

Did something different open with the link? It should have been the bypass that I am using.

 

[swathdiver]

Now that I have bypassed the AFM, what else would an actual tune do for me?

It will improve the performance and life of your transmission too. The engine will make more power and it will turn off AFM permanently, more reliably than an OBDII adapter.

I would not think that AFM would be engaging at speeds over 80 mph. Maybe you have a bad motor mount that needs changing. When my AFM was active, it worked seamlessly, never felt it engage.

 

[Marky Dissod]

Engine Half@$$ activating over 80MpH (with the GM OE 'tune') is a bit strange ...
OK, V4 mode is disabled. There are other things to improve for the engine & the transmission.

To OVERSIMPLIFY:
Engine can be made more responsive, more efficient, and more powerful,
even if you haven't spent a dime on any engine mod hardware, even if you only use 87 octane.
Transmission can be made more responsive, more durable, and more reliable,
so that it and the engine will both last longer regardless of how hard the powertrain works / plays.

Only performance mod that is also a maintenance upgrade, and is therefore THE best bang-for the buck,
is 3.42 / 3.73 / 4.10 axle(s) (depending on what your vehicle came with originally).

 

[Joseph Garcia]

^^^^^x2^^^^^

A tune is simply the best bang for the buck that you can do for your truck.

I believe that @Cut Wagon recently got a BlackBear Performance tune on his truck, and he may be able to give you a first hand review.

 

[j91z28d1]

Did something different open with the link? It should have been the bypass that I am using.

my fault, reading it felt like a sales ad that doesn't really make since, as afm shouldn't activate at the engine load needed to hold 80mph.

I didn't realize you had other posts.

 

[Noggles]

Just as an FYI, the disablers (and tunes for that matter) don't completely stop the DOD failure. The only real way to be sure is to mechanically delete the system via a cam and lifter swap. Plus then you get even better performance from a bigger cam.

 

[mikez71]

Now that I have bypassed the AFM, what else would an actual tune do for me?

Possibly eek a little more responsiveness out of the engine? Not sure, but definately to tune engine mods.
Change your rev-limit, but that hasn't seemed very beneficial on my stock 5.3..

If you feel like your transmission ever lugs a little or hunts between gears, that can be fixed.
Transmission shift scheduling is tweaked to be more responsive (or whatever you want, but the factory is a little lazy at times forsure)
Torque converter unlock in lower gears is pretty standard for smoother shifting and torque multiplication..

Some people like the cooling fans to come on earlier.. There's a few other tidbits like correcting your speedo for tire/gear changes, alternator settings, speed limiter can be changed... idle speed..

Also, you can eliminate the dongle thingy you just bought

 

[Gearz]

I have had my Range Technology AFM delete and it does what it says for $150 bucks in 2015. Don't leave it plugged in if your truck will sit for a few days because it will draw on the battery. I installed dual exhaust so it doesn't make that 4 cylinder popping sound anymore. All in all it has been great and with 150K the engine sounds like new with plenty of power so it does eliminate lifter wear because they never activate and hammer the cam! My engine has never been apart and I don't expect to either.

 

[LSCALADE]

If you ever dig around HP tuners you will see the slip allowed tables for V4 vs V8 and they vary quite a bit so if you are going 80mph you are probably at a threshold of the TC slipping and it could feel like a mutated vibration when its doing that. YOu can get a ScanGauge 3 and monitor the slip and you will see in V8 you are gonna be around 20rpm slip but you could be around 40-60rpm slip in V4 mode and if you are somehow out side of that desired slip you will feel shudder.

On an old beat up unit like mine, I was able to adjust the gain offset and max line pressures as well as ramp in values and got the TC shudder to basically disappear except under heavy load up a slight incline in 6th gear the load on the locked clutch is too much and it would slip aka my RPM would jump from 0RPM slip to 20-100rpm in a second and you will feel the shakes, but the TC lock up logic also allows you to unlock the TC above 25% load so now when going up the same inclines it feels like I went from 6th gear to 5.5 gear with the TC unlocked the slip jumps to 200-300rpm and it pulls nicely until you let off and then locks again. I could probably sell the vehicle as is and no one will ever know it has a TC issue.

 

[j91z28d1]

If you ever dig around HP tuners you will see the slip allowed tables for V4 vs V8 and they vary quite a bit so if you are going 80mph you are probably at a threshold of the TC slipping and it could feel like a mutated vibration when its doing that. YOu can get a ScanGauge 3 and monitor the slip and you will see in V8 you are gonna be around 20rpm slip but you could be around 40-60rpm slip in V4 mode and if you are somehow out side of that desired slip you will feel shudder.

On an old beat up unit like mine, I was able to adjust the gain offset and max line pressures as well as ramp in values and got the TC shudder to basically disappear except under heavy load up a slight incline in 6th gear the load on the locked clutch is too much and it would slip aka my RPM would jump from 0RPM slip to 20-100rpm in a second and you will feel the shakes, but the TC lock up logic also allows you to unlock the TC above 25% load so now when going up the same inclines it feels like I went from 6th gear to 5.5 gear with the TC unlocked the slip jumps to 200-300rpm and it pulls nicely until you let off and then locks again. I could probably sell the vehicle as is and no one will ever know it has a TC issue.

kinda crazy they let them slip all the time and wonder why the tranny doesn't last like the used to.


on a side note that's interesting, I have a hybrid one and there's no torque converter between the tranny and engine. Just a flex plate. the truck stock had very aggressive afm. trying to save as much fuel as it can and has the electric motors in the tranny to assist and stay in v4 longer. I wonder how they cushioned the transition in these. I only drove it a little while before disabling it on the road trip home with hptuners. I didn't feel anything driving thru. Just watched the dash switch in and out. I'd wonder if they used the tranny gears to slip, but these trannys commonly go 250k plus if you change the fluid as recommended. so I doubt there was any slip programed in there. but since hpt tends to avoid hybrid tuning. I have zero access to tranny tune settings to see.

 

[Marky Dissod]

Possibly eek a little more responsiveness out of the engine? Not sure, but definitely to tune engine mods.
Change your rev-limit, but that hasn't seemed very beneficial on my stock 5.3L.

DEFINITELY eek out more engine responsiveness. Y'know the 'Roar Pedal' / 'Pedal Commander' / etc?
There are ecm tables that decide the delayS between your foot moving & the throttle moving.
There are other ways to improve throttle response that predate electronic signal throttle,
but that one is the most obvious.

GM OE 5.3L cams are selected such that there's almost nothing to gain by revving any higher.

If you feel like your transmission ever lugs a little or hunts between gears, that can be fixed.
Transmission shift scheduling is tweaked to be more responsive (or whatever you want, but the factory is a little lazy at times for sure).

If you do NOT feel like your transmission lugs or hunts between gears,
it's only because you don't know how much a competent tuner can accomplish here.
None of the hardware differences between the various 6.2L V8s are as important as the tuning differences.

 

[Familyman2112]

Interesting, my stock tranny died at 102k, the rebuilt trans died at 127k (1k out of warranty) and bought a remanufactured and the vehicle now has 138k. Would a tune possibly have helped my stock trans live longer? I don’t have an extra $780 laying around for a Black Bear. If I try to find someone locally, what questions should I ask to see if they know what they’re doing?

 

[Geotrash]

Interesting, my stock tranny died at 102k, the rebuilt trans died at 127k (1k out of warranty) and bought a remanufactured and the vehicle now has 138k. Would a tune possibly have helped my stock trans live longer? I don’t have an extra $780 laying around for a Black Bear. If I try to find someone locally, what questions should I ask to see if they know what they’re doing?

An unequivocal YES. GM builds too much slip into the lockup of the torque converter (TC), for slightly smoother shifting feel. That, combined with the constant TC micro-slips induced by the AFM system engaging/disengaging tears the converters up in less than 150K miles - often way less. Getting a tune will prolong the TC's life through a combination of less slipping and the fact that it permanently turns off AFM in the ECU. If you really want to have it go the distance, have a TC with a stronger lockup clutch and billet cover installed.

I wonder...did the shop who did your first transmission rebuild also replace the TC? If not, that could well have been what took it out the second time.

 

[Marky Dissod]

... did the shop who did your first transmission rebuild also replace the TC?
If (they did) not (replace the TC), that could well have been what took it out the second time.

Word.