Afm

[06 Taco]

I've read every thread that I could find for the last couple of years and this is the first time that I read that deleting AFM effects your transmission. I've been using a Range Technologies OBDI AFM disabler on my 2015 Yukon Denali for about 20,000 miles with no issues. I have the 6.2 with the 8 speed tranny. Am I fixing one issue only to cause another problem?

 

[L8T BURB]

I've read every thread that I could find for the last couple of years and this is the first time that I read that deleting AFM effects your transmission. I've been using a Range Technologies OBDI AFM disabler on my 2015 Yukon Denali for about 20,000 miles with no issues. I have the 6.2 with the 8 speed tranny. Am I fixing one issue only to cause another problem?

My stance is that disabling AFM via tune only or a full mechanical AFM delete will impact the transmission, but in a good way. The engine jumping between V4 and V8 is troublesome for the TCC and transmission in general. Generates more heat and unnecessary friction on the wear parts inside the transmission.

I would recommend a couple things for you.

1. Get a reputable tuner to write a tune for your Yukon that disables AFM. (No need for range device after this)
2. Also have reputable tuner write a tune for the transmission that will fully disable TCC slippage in all gears. In addition, in my 6L80, my tuner only enabled TCC lockup in gears 5/6. With you having the 8-speed, research which gears are ideal for TCC lockup. I assume gears 7/8 but thats a total shot in the dark. Don't take me at my word on that part lol.
3. Get a thermostat bypass for the transmission. In addition to the crappy OEM tuning of the transmission causing it to operate at a higher temperature, the thermostat is also a known culprit to the heat. The factory GM transmission thermostat doesn't open until around 192 degrees and even sometimes will run over the 200 degree mark. For most transmissions that may be fine, but these GM transmissions do not live long under continued use at those temperatures.

For reference, I had an engine and transmission tune written for my 2015 Suburban for $150. This included about 3 different revisions to iron out the very fine details.

 

[Marky Dissod]

My stance is that disabling AFM via tune only or a full mechanical AFM delete will impact the transmission, but in a good way.
The engine jumping between V4 & V8 is troublesome for the TCC and transmission in general;
it generates more heat and unnecessary friction on the wear parts inside the transmission.

It's also GM's stance, on two different subjects.

Engine Half@$$ (I've no respect for V4 mode) isn't good for the engine or the transmission.
It trades engine longevity & durability for not enough MpG.

GM tunes the torque converter clutch behavior differently between civilian / 1500 vehicles vs heavier duty vehicles.
GM does not want civilian customers to feel or notice the TCC locking or unlocking,
so 1500 vehicles have the TCC tuned to slip by GM OE.
Heavier-duty vehicles not only avoid Engine Half@$$ (and 'Cylinder Confusion'),
they also do not bother slipping the TCC lockup or release to try to soften or hide it.
A more thorough aftermarket tune (among MANY other things) 'borrows' this heavier-duty TCC behavior,
which increases transmission durability & longevity, especially when combined with ATF servicing.

Disabling Engine Half@$$ is a GREAT IDEA in and of itself; it improves the engine's odds of lasting much longer,
but if this disablement is done with a plug-in, the light-duty TCC slip is left as is.
Although disabling Engine Half@$$ helps the transmission too, it can never help as much as a thorough tune.

 

[Marky Dissod]

Separate from Engine Half@$$ / Cylinder Confusion,
torque converter lockup is another tradeoff between MpG vs durability / longevity.
When MpG is the goal AND the risk to the powertrain is lowest - when driving 'gently' -
locking the TCC helps MpG and has little to no negative impact on durability / longevity.
This typically applies to the direct-driven / 1-to-1 gear and the overdriven gears in a transmission.

 

[Marky Dissod]

Continuing the above ...
The torque converter clutch's ONLY goal is MpG, specifically, enhancing MpG in the gear you're already in.
The above assumes the goal at the moment is to improve MpG, which is why the 6L80 8L90 & 10L80 are capable of locking the TCC in every gear (except 1st). (Even the 4L60E can lock the TCC in 2nd! - can, but NOT should.)

TCC wear is minimized by (not only) zeroing out what GM considers acceptable TCC slip (in the tune), but
also by tuning it out entirely in the underdriven gears.
6L80 lacks a direct-driven gear, so tuning out TCC lockup in 3rd & 4th costs an MpG or 2, but this buys longevity.
For the 8L90, tune out all TCC lockup in 3rd 4th & 5th - only use the TCC in 6th 7th & 8th.
For the 10L80, tune out all TCC lockup in 3rd 4th 5th & 6th - only use the TCC in 7th 8th 9th & 10th.

(I'm aware that the 10L90 tcm is presently difficult to access for the prpose of aftermarket tuning - just saying.)

TL;DR:
Disabling Engine Half@$$ or Cylinder Confusion helps both engine and transmission last longer.
However, plug-in canned 'tunes' don't go anywhere near as far in terms of benefits to powertrain longevity.
A more thorough tune, either by mail-order, or in person, includes a plethora of other benefits.
Chief among those extra benefits is extending the life of the TCC, and the transmission as a result
Even if this costs a few highway MpG, most people would prefer a vehicle that lasts much longer.

 

[blondie70]

A mechanic is writing a transmission tune for me. Will notify when it's ready. Says it's gonna be about $300. I already have AFM disabled. I told him the list of things I wanted that I got from here (as above posts by Marky)
He said these things should prolong the life of the trans.....but.....seems like these transmissions have some kinda death wish or something...ha ha
Mine is working perfectly now at about 199K. Trying to keep it that way.