2018 Yukon, tune to help trans?

[88lance]

Hey everyone, got a 2018 Yukon with a 6.0. The only issue I am running into, is that it slams into 3rd sometimes pretty hard. Long story short, dealer says it's fine, even though it's clearly not shifting correctly. They aren't going to do anything about it.

Well, back in 2011 I had an F150 that was doing this exact thing. Dealer "fixed it" about 5 times, and it just kept coming back. They just gave up on it.
Well, I was itching for more 5.0 power, and got a tuner, 5-Star Tunes for performance. It mentioned that it also changed the way the trans shifts, even though that's not what I was really buying it for.
Well, surprise, it fixed the shift problem. Completely. Shifted smooth as could be for the next 100k miles till I sold it.
So now with this Yukon giving me the same crap, I'm wondering if this could be the fix again. So I have a couple questions since I haven't had many GMC's.

-who are the top dogs in tuning for the 6.0? I would prefer somebody that has made a good name for themselves since a crap-tune can damage a lot of expensive stuff. I'll drop the necessary money for one.

-Do the tunes for these 6.0's also change the transmission, like they do in the Fords? I'm not really looking for performance in the trans, I just want it to teach it to shift correctly like it did on the F-150.

-Im not really looking for a huge power increase in the 6.0, it scoots pretty well already, but if they have a tune that gives it a little more "go" while it's helping the trans, that's would be nice. What tunes would you suggest ordering from the tuner you recommend?

 

[Doubeleive]

Hey everyone, got a 2018 Yukon with a 6.0. The only issue I am running into, is that it slams into 3rd sometimes pretty hard. Long story short, dealer says it's fine, even though it's clearly not shifting correctly. They aren't going to do anything about it.

Well, back in 2011 I had an F150 that was doing this exact thing. Dealer "fixed it" about 5 times, and it just kept coming back. They just gave up on it.
Well, I was itching for more 5.0 power, and got a tuner, 5-Star Tunes for performance. It mentioned that it also changed the way the trans shifts, even though that's not what I was really buying it for.
Well, surprise, it fixed the shift problem. Completely. Shifted smooth as could be for the next 100k miles till I sold it.
So now with this Yukon giving me the same crap, I'm wondering if this could be the fix again. So I have a couple questions since I haven't had many GMC's.

-who are the top dogs in tuning for the 6.0? I would prefer somebody that has made a good name for themselves since a crap-tune can damage a lot of expensive stuff. I'll drop the necessary money for one.

-Do the tunes for these 6.0's also change the transmission, like they do in the Fords? I'm not really looking for performance in the trans, I just want it to teach it to shift correctly like it did on the F-150.

-Im not really looking for a huge power increase in the 6.0, it scoots pretty well already, but if they have a tune that gives it a little more "go" while it's helping the trans, that's would be nice. What tunes would you suggest ordering from the tuner you recommend?

you do not have a 6.0 it's either a 5.3 or 6.2 (unless someone did a custom swap)
in either case blackbear performance can help you out.
@BlackBearPerf

 

[88lance]

you do not have a 6.0 it's either a 5.3 or 6.2 (unless someone did a custom swap)
in either case blackbear performance can help you out.
@BlackBearPerf

Correct, 6.2, sorry. Got used to Ford numbers.
I'll check them out, thanks.

 

[B-train]

If you have the 8 speed, have it flushed with the new GM fluid if it hasn't been done to your knowledge. Fixed the shudder and harsh shifting occasionally in my 2017. Been great since - 90k

 

[88lance]

Seeing a lot about Diablew as well. Do both companies have hand-held tuners that they can send with loaded tunes?

 

[88lance]

If you have the 8 speed, have it flushed with the new GM fluid if it hasn't been done to your knowledge. Fixed the shudder and harsh shifting occasionally in my 2017. Been great since - 90k

This one has the 10 speed, but it may still fix it.
They wanted $800 to do the change, but if it fixes the shifting, It may be the way to go.
It's at 90,000 mi, it may actually be time for a flush anyway.

 

[B-train]

If it's never been done, it's DEFINITELY time. Stick to a 40k interval on these new ones for longevity

 

[Doubeleive]

Seeing a lot about Diablew as well. Do both companies have hand-held tuners that they can send with loaded tunes?

With BB you can use a Autocal which is a handheld

 

[88lance]

If it's never been done, it's DEFINITELY time. Stick to a 40k interval on these new ones for longevity

Wow, yeah it doesn't show that it's been done in the records, unless a random shop did it with the previous owner. I'll go ahead and put that on my list. If that will actually fix it, I may not bother with the tune on it.

 

[88lance]

With BB you can use a Autocal which is a handheld

Great, That's what I had on the Fords and I really liked it. Especially because I could return to stock if it was going into the dealership for anything that they may flash the computer for. Plug it in, return to stock, get it back, throw the tune back in

 

[Tahoe14]

$800 for a fluid change. I would get other quotes from tranny shops.

 

[89Suburban]

@NickTransmissions

 

[BlackBearPerf]

Correct, 6.2, sorry. Got used to Ford numbers.
I'll check them out, thanks.

We would be happy to help! You can use the below link to send us an email or give us a call and we can go over everything with you:

Contact

Please be sure to check out our frequently asked questions for answers to many common questions. Business hours are Monday to Friday: 8:00 AM- 4:00 PM. Vehicle Build/Engine Swap Questions by Email Only, Please. Coeur D'Alene, ID 877-809-4070 [email protected]

www.blackbearperformance.com

 

[sealandsky]

I would start with a transmission FLUSH, not just a fluid change. Also have the filter cleaned. Once that's done then move on to the tuning of the ECM and the TCM.

 

[blackelky]

This one has the 10 speed, but it may still fix it.
They wanted $800 to do the change, but if it fixes the shifting, It may be the way to go.
It's at 90,000 mi, it may actually be time for a flush anyway.

Wtf my dealer charges 300 for this and i thought that was high

 

[Marky Dissod]

1. Even though they are overcharging you for the ATF change and new ATF filter (when I read $800 I threw up a little), still much cheaper than a replacement 10L90E.

2. GM's OE 'tune' is not only part of the reason why this Yukon is giving you the same crap, it's also why you NEED a 40K ATF & filter interval.
(Although I'd never recommend a longer one anyway.)

 

[MrMonte]

Wtf my dealer charges 300 for this and i thought that was high

For $300 are they doing a full 11qt flush or just dropping the pan, replacing the filter then adding 4qts? That's a 10 minute job on the 10 speeds.

My neighbor paid $800 for a full trans flush & filter on his 2018 8 speed. I did my 10 speed last week & took 90 minutes & even did a tire rotation. Cost me $125 for 12qt of ULV & a filter. Pretty easy job.

 

[blackelky]

For $300 are they doing a full 11qt flush or just dropping the pan, replacing the filter then adding 4qts? That's a 10 minute job on the 10 speeds.

My neighbor paid $800 for a full trans flush & filter on his 2018 8 speed. I did my 10 speed last week & took 90 minutes & even did a tire rotation. Cost me $125 for 12qt of ULV & a filter. Pretty easy job.

Reverse flush

 

[MrMonte]

Reverse flush

The reverse flush will help clean your filter if you don't want to drop the pan & replace it. I always do a forward flush after changing the filter by disconnecting the transmission return line from the radiator, stick a 3/8" hose in the radiator fitting, start the engine & let trans fluid drain as I added more.

When you do a reverse flush on transmissions, there is the possibility any buildup will be removed. When you remove the buildup, all you have is worn bands/clutches left. Sometimes, after the flush, you'll find your transmission starts slipping and rebuild or replacement will be following not long after. The buildup will actually support the transmission and allow it to last longer than without it.

 

[blackelky]

The reverse flush will help clean your filter if you don't want to drop the pan & replace it. I always do a forward flush after changing the filter by disconnecting the transmission return line from the radiator, stick a 3/8" hose in the radiator fitting, start the engine & let trans fluid drain as I added more.

When you do a reverse flush on transmissions, there is the possibility any buildup will be removed. When you remove the buildup, all you have is worn bands/clutches left. Sometimes, after the flush, you'll find your transmission starts slipping and rebuild or replacement will be following not long after. The buildup will actually support the transmission and allow it to last longer than without it.

Yeah i changed the filter first and added about 7 quarts that came out. I'll get them to do the reverse flush in like 6 mos. I don't drive my tahoe very often