'17 - '18 "Tuner" advice???

b00001 · August 9, 2019

I have searched and read many of the 70 page thread on Tuners. Not finding what I am looking for pertaining to my 2018 w/ 8 speed. Surely many have been through what I am going through now. Looking for a good path to follow.

I have a 2018 Sierra SLT, 5.3 w/ 8 speed that I have installed Corsa Sport cat back exhaust as well as upped my tire size from basically a 32" to a 33" tire (went from 275/55/20 to 275/60/20).

I plan on doing the OEM airbox mod + install high flow air filter such as K&N or the dry blue filter.

My "problem" started just after I installed the new tires a few days ago. It seems am feeling the weight of the new tires as well as the increased size of the tires affecting how the truck is driving. I have the 8sp trans and before the tires, it was actually not too bad. Now with the new tires, I can feel that sluggish shifting, as well as the trans trying to shift into the next highest gear way too soon. I have heard that the trans is reading the old tire size = speed, so the shift points will be slightly off??? I understand there is no option for transmission tuning.

My question is, what would be the best way to get my truck back to feeling GOOD again while keeping budget in mind? (Just lost my job) What would be my least expensive way to get my truck dialed in? Do I need a full "tune" or would something like the $199 Superchips tuner suffice? That would allow me to turn off DOD as well as reprogram for the larger tires. I think I have about another year of warranty left that I would like to keep in good standing if possible.

Thank you all very much in advance!!!

Jacoby · August 10, 2019

The 8 speed is where your problem is. Hard to get the trans tuned but it’s doable. You can still get a tuner for the engine and adjust for the tire size to at least get your speedo right. Engine tune will get a little pep back.

You'll get lots of suggestions but I suggest you get with Lew at daiblewtune.com he’ll hook you up.

b00001 · August 10, 2019

Understood. I have a mail into Lew.

Just to reiterate, before the tires, the trans was shifting marginally "ok". Now, it feels a bit off. Makes me think that if I could adjust for the tire size, maybe the parameters will come back into some sort of alignment and the shifting will be a bit better...??

Jacoby · August 10, 2019

Yeah it’s short shifting because the ratio is off. A tuner should get it back to the way it was.

pewterliftedz · August 11, 2019

Easiest way to get the trans shift points fixed, and avoid any warranty issue would be to get a Speedomoter calibrator from Hypertech or something similar. If you get a device that "tunes" the trucks engine, you can kiss any sort of engine warranty good bye.

Your trans CAN be tuned, it just requires that you send your TCM into HP Tuners to be unlocked for $200, then you need to pay a tuner to tune the engine and trans. FYI it costs $200 in HP Tuners credits to tune the engine and another $200 to tune the trans. Then you still have to pay the tuner for their services, it's an expensive endeavor, I was quoted $1100 in total.

If you just perform a engine tune through HP Tuners, EFI Live, or Diablo, they will all be able to adjust you tire height to fix you speedometer without having to mess with the trans.

Jacoby · August 11, 2019

6 hours ago, pewterliftedz said:

If you get a device that "tunes" the trucks engine, you can kiss any sort of engine warranty good bye.

Not true

pewterliftedz · August 11, 2019

8 hours ago, Jacoby said:

Not true

GM isn’t going to replace or repair anything engine related if they detect a tune. It doesn’t void your complete warranty, but you would be hard pressed to find a dealer to do engine warranty work.

b00001 · August 11, 2019

Thank you guys for the insight so far, really appreciate it!

At this point, I think I will try to find the Superchips or Hypertec or something to adjust the tire size and maybe remove the DOD. I really do not want to spend $600-$700 and possibly run into any warranty issue of ANY sort. I have another year or so of powertrain left I believe. Hopefully the tire size adjustment will get the trans shifting back as it should.

I will dig around and see if maybe there is a used unit floating around out there....If you guys come across one, let me know.

Jacoby · August 11, 2019

1 hour ago, pewterliftedz said:

if they detect a tune.

This is true and what you should have said to begin with. Just because you tune your truck doesn’t mean you have no chance of getting an engine related issue fixed under warranty.

Youll find more more instances of people with tunes getting warranty work done then people with tunes and getting denied. It’s a fact.

1 hour ago, b00001 said:

Thank you guys for the insight so far, really appreciate it!

At this point, I think I will try to find the Superchips or Hypertec or something to adjust the tire size and maybe remove the DOD. I really do not want to spend $600-$700 and possibly run into any warranty issue of ANY sort. I have another year or so of powertrain left I believe. Hopefully the tire size adjustment will get the trans shifting back as it should.

I will dig around and see if maybe there is a used unit floating around out there....If you guys come across one, let me know.

You have to tune the truck to turn off AFM.

pewterliftedz · August 11, 2019

1 hour ago, b00001 said:

Thank you guys for the insight so far, really appreciate it!

At this point, I think I will try to find the Superchips or Hypertec or something to adjust the tire size and maybe remove the DOD. I really do not want to spend $600-$700 and possibly run into any warranty issue of ANY sort. I have another year or so of powertrain left I believe. Hopefully the tire size adjustment will get the trans shifting back as it should.

I will dig around and see if maybe there is a used unit floating around out there....If you guys come across one, let me know.

You will need 2 separate devices to fix tire size and turn off DOD without a tune. Hypertech Speedomoter calibrator for tire size and a Range AFM Disabler for the DOD. This would be the only way to get both things you want without tuning the truck.

mookdoc6 · August 12, 2019

HP Tuners end of story!

Jacoby · August 12, 2019

Forgot about the Range. That will get the afm turned off. The Hypertech isn’t the only option for tire size adjustment. Rough Country has a programmer that’s quite a bit cheaper.

b00001 · August 12, 2019

56 minutes ago, Jacoby said:

Forgot about the Range. That will get the afm turned off. The Hypertech isn’t the only option for tire size adjustment. Rough Country has a programmer that’s quite a bit cheaper.

You talking about this one: HERE ??

Jacoby · August 12, 2019

44 minutes ago, b00001 said:

You talking about this one: HERE ??

Yeah

b00001 · August 12, 2019

In construction, that looks identical to the Hypertec Speedometer Calibrator HERE

I assume it is the same piece of equipment. I am leaning towards this route. Hopefully the correct tire size in the computer will clean up the shifting to what I had before the tire upgrade.

Thanks again all!