TRNW-2: 6L hp tuning

[jbockus at hiwaay.net]

I can tell you from personal experience on my own vehicle that the 
mileage is not affected by disabling the AFM, I drove my truck for a 
year before having it HP tuned and have know driven it for 3 years since 
the tune and there has been absolutely no difference in my fuel mileage. 
And the truck runs and drives so much better. 16 GMC Sierra 4x4. Before 
when the torque converter locked up at 10 mph, it felt like a dog, I had 
to accelerate harder to help delay lockup so it wouldn't fall on its 
face when lockup engaged. We always tell our customers that this is part 
of the rebuild process and when you tell them you will be disabling the 
AFM and their engine will stay in V8 mode all the time, they get 
excited, I've found it to be a great selling point to my customers. They 
all say, "I've always hated when my truck goes into 4 cyl. mode" and 
heck yes, build it!

A few years ago before I was aware of HP tuning, I owned a 2007 Tahoe 
that was using oil and while driving through a parking lot at low speeds 
(around 10 mph), it felt like the torque converter was staying engaged 
causing a low speed vibration/chugging, I checked out my information 
center and the engine was staying in 4 cyl mode even with my foot off 
the gas. At that time, I purchased a Range Technology box to disable 
AFM, and it fixed it! I went from using 3 qts. of oil between changes to 
1/2 qt. and it got rid of the low speed vibrations too.

On 2025-11-03 6:46 am, Tod Chretien via trnw2 wrote:
> By disabling the DOD you are doing the customer a tremendous favor.
> Whether they realize it or not. I don't think the gas savings makes up
> for the potential engine failure.
> 
> Although, it's totally wrong to turn it off without asking the
> customer first. It's also illegal to turn it off here in California.
> I'm not sure if and how they are enforcing that though.
> 
> --
> Best Regards,
> Tod Chretien
> TRNW Inc.
> https://www.trnw.net
> 
> On 11/1/2025 6:40 AM, Steve Everett via trnw2 wrote:
> 
>> I agree with you Fred,  I don't mess with it because I don't want to
>> tinker too much with the way it works, if the customers engine isn't
>> running perfect any little misfire or stumble will be amplified with
>> tcc slip set to zero,  and to my knowledge there have been no torque
>> converter related comebacks on any of the units we've just delayed
>> the apply till 4th or 5th,  the early apply the factory has is
>> apparently the main reason for the converter failures
>> 
>> and if  you are going to zero the tcc slip then you'll have to
>> disable DOD, and I'm not doing that unless the customer is okay with
>> it, a shop I worked at previously was doing it on every build and
>> never asking or informing the customer they did it,  only admitting
>> if the customer come back saying their mileage deteriorated on
>> highway trips
>> 
>> Steve
>> 
>> Steve
>> 
>> On Sat, Nov 1, 2025 at 9:27 AM Fred Whitaker via trnw2
>> <trnw2 at trnw.net> wrote:
>> 
>>> There were several threads on the HP tuners forum a few years
>>> ago where TranyBob was explaining why you don't want to set
>>> converter slip to zero. Something about warping the apply piston I
>>> believe.  I have no idea if that line of thought still holds true.
>>> But I will never mess with slip.
>>> I will disable lock up below 4th or 5th ,or a certain speed in
>>> trucks that haul. But for the average truck I just don't see the
>>> need to mess with it. I know a lot here disagree. It's just my
>>> opinion.
>>> -------------------------
>>> 
>>> From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of
>>> Phil Materi via trnw2 <trnw2 at trnw.net>
>>> Sent: Friday, October 31, 2025 5:46 PM
>>> To: Brett Karulak <brettsb16a2 at gmail.com>; Technical Discussion
>>> Forum <trnw2 at trnw.net>
>>> Subject: Re: TRNW-2: 6L hp tuning
>>> 
>>> We are turning TCC off in 1,2,3 and not adjusting any apply or
>>> slip speeds.  We live in a city with a lot of stop and go traffic,
>>> and very hilly terrain.  We first tried changing other TCC
>>> parameters like others have mentioned and nothing but complaints.
>>> Now that our local TC build shop has figured out how to make the
>>> TCs last without redeveloping a shudder, they work well with just
>>> turning TCC off in 1,2,3.
>>> 
>>> Phil Materi
>>> A&B Transmissions
>>> Langley, B.C.
>>> 
>>> -------------------------
>>> 
>>> From: trnw2-bounces at trnw.net <trnw2-bounces at trnw.net> on behalf of
>>> Brett Karulak via trnw2 <trnw2 at trnw.net>
>>> Sent: October 31, 2025 11:39 AM
>>> To: Technical Discussion Forum <trnw2 at trnw.net>
>>> Subject: TRNW-2: 6L hp tuning
>>> 
>>> Those who are tuning, I know it's popular to command lock up only
>>> in 5th and 6th.  Do any of you let it lock up in 4th also?  I just
>>> tuned one and left 4th strategy alone, no lock up 1-3 and zero
>>> slip speed in 5th and 6th.  Just wondering what most of yall do.
>>> It felt great and not sure if it really matters.
>>> 
>>> Thanks,
>>> Brett Karulak   This message was sent from the TRNW Technical
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>>> TRNW Inc., 2825 Walnut Terrace, Modesto, CA 95355
>> 
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