New to the 6.2l world- Have some Questions

[Charles P.]

Hey Everyone!

 

I just got a 2017 Sierra SLT over the weekend with a 6.2l engine and 8-Speed Tranny. 85,000 Miles

The previous owner had done the following that I can tell from Carfax and looking around:

-Aftermarket Headers

-MBRP Full Exhaust system

-Catch can setup

-Heads taken off and gaskets replaced (Per carfax)

-Differential Fluid changed

-Differential Cover changed

 

I am trying to read up on everything about it and I had some questions that may be obvious or simple but I am having a hard time finding the answers to.

1.Im not entirely sure if the truck has a tune or not.Is there a good way to tell?

2.Would a custom tune disable AFM?

3.Do I empty the Catch can often?

4.Should I do the TSB 8 Speed fluid change at its current miles? Or is it too late?

5.Any advice/ info to a new 6.2l anyone has? Im wanting to know as much as I can.

 

I am looking for this truck to be a 15 year truck. So maintenance and must do's are very important to me.

Thanks for any help!

 

[kennerz]

I  have a 15' and am not sure if these trucks have the kind if quality to last 15 years. It may, but not sure.  If anything the trans will go with high mileage. Maybe with a tune and large cooler & clean filter it will be OK.

 

To tell if it has a tune a couple of things:

1. does it go into AFM mode or not? if not probably tuned.

2. Does it go over 99 mph? some say tire speed rating determines this, my 15' would not do over 99 before tune.

3. How does it feel at part throttle pulling away from a stoplight? untuned with traction control on they are boggy and soft.

4.  if it totally rips and doesn't do any of the stuff above, it's probably tuned.

 

Catch can should be checked every 3k mi or so. Usually won't be much, but once I left if for about 5k and it was about half full using the basic elite catch can.

 

If your truck has all that exhaust stuff and doesn't have a cold air or tune I would get both. There are 2 or 3 proven cold air intake designs, all the rest are not worth it. Tune makes the single largest difference on a stock truck.

 

I would change the trans fluid asap and have the filter changed too. ignore the recommended service interval if it says that 85k is too soon.

I'm trying to figure out myself what the best course is for the tranny to attempt to get full life out of it. I'm at 65k now and am thinking add a dip stick, new filter, and possibly the largest cooler like 40,000gvr, and do the thermostat removal mod. Also use the new mobil 1 trans fluid that is recommended recently.

 

Use good oil & filters (right now I'm running amsoil 0~40 full synthetic and WIX- however there are other good combinations out there).

 

You could clean the MAF with the proper MAF cleaner, make sure all vacuum hoses are in good condition. Noticed that the brake booster pump line needed to be pressed on tight and my pedal felt better (no leaks).

 

I home ported my throttle body and got somewhat better response by carefully blending the ledge on the TB and purposefully not touching the blade/or bore.

 

Could do plugs and wires too at this point, I consider that more maintenance than a mod. I'm running MSD/NGK with good results.

 

none of these are powerhouse type crazy mods, just in concert all together the truck Will run a lot better than stock, and be a lot more fun to drive and with the mods being soo mild you give up pretty much no reliability.

 

Good Luck, they're good trucks, just need a little bit of TLC to make them run right.    

 

[Charles P.]

Awesome Info!

 

Thank you,

I forgot to mention that it does have a Cold air intake. Im not sure what brand atm, I want to say Air raid? I will have to check.

 

It sure does rip off the line, I find myself spinning tires just turning the truck with barely any pedal*. I am hoping AFM is disabled. From the sounds of it, the truck is a ticking time bomb with it.

 

I think the plugs are newer- I should definitely check these though thanks, looks like It has aftermarket wires so im hoping something has been done.

 

I will definitely do the Tranny fluid AND filter- good info there

 

I am still learning what has/ has not been done. I appreciate it!

[truckguy82]

Do tranny fluid and the transfer case

 

-relevant info

 

-auto4wd is the same as awd, it can handle quite a bit of power

-the 6.2 is the same long block as the corvette lt1, only difference in exhaust and intake manifolds.

-if you never see “v4” displayed, afm is probably disabled

[Charles P.]

Thanks, Its sitting in 2wd at the moment-havent touched Auto except to make sure it works.

 

Where would I see the v4 pop up? Im in the process of RTFM but is this prominently displayed in a certain area? 

 

I have not seen it yet.

[damnthetorpedoes]

1 hour ago, Charles P. said:

Thanks, Its sitting in 2wd at the moment-havent touched Auto except to make sure it works.

 

Where would I see the v4 pop up? Im in the process of RTFM but is this prominently displayed in a certain area? 

 

I have not seen it yet.

On the center info screen, set it to instant fuel economy and it will be in the bottom right corner. Will change between V8 and V4 (if AFM is enabled).

[Charles P.]

Got it. Would it go into V4 at idle or Park?

[JimCost2014]

7 minutes ago, Charles P. said:

Got it. Would it go into V4 at idle or Park?

No, only will activate at speed with very light throttle.

 

V4 is highlighted in green, V8 will be blue in the display.

[Charles P.]

Good to know. Thanks! 

 

Also, I apologize, Im sure this is like a broken record at this point in the forums.

[JimCost2014]

13 minutes ago, Charles P. said:

Good to know. Thanks! 

 

Also, I apologize, Im sure this is like a broken record at this point in the forums.

You are very welcome.

 

Sometimes it is just easier to ask again, rather than search 5 years worth of posts.

[Charles P.]

I'm happy to report that it stays in v8 the whole time!

Seems like a lot was done to this bad boy.

[DenaliX14]

On 8/20/2019 at 8:16 AM, truckguy82 said:

Do tranny fluid and the transfer case

 

-relevant info

 

-auto4wd is the same as awd, it can handle quite a bit of power

-the 6.2 is the same long block as the corvette lt1, only difference in exhaust and intake manifolds.

-if you never see “v4” displayed, afm is probably disabled

The block casting is the same GM 6.2 as the LT1/4/5. Same bore size, connecting rod and piston size. Same style injectors, fuel pump etc. 

[TRKLGND]

Only 2 years old with 85,000 miles, tuned, mods... I'll bet the old girl has had the piss run out of her.  Unless I knew the previous owner I wouldn't have touched it.  But you did so we are passed that.

Change every fluid period.  Start saving for a trans rebuild.  Good luck.  I mean that.  

[Charles P.]

5 minutes ago, paracutin said:

Only 2 years old with 85,000 miles, tuned, mods... I'll bet the old girl has had the piss run out of her.  Unless I knew the previous owner I wouldn't have touched it.  But you did so we are passed that.

Change every fluid period.  Start saving for a trans rebuild.  Good luck.  I mean that.  

Eek, you sound upset that I even bought the truck.

Yeah I always have money saved for that.its not a concern in my eyes at the moment.

Otherwise this thing has been fantastic. I dont regret it coming from what I had that's for sure.

 

Also, looking at everything and how it's been taken care of i knew what I was looking at towards previous owner. It was a show pony for sure.

 

 

 

 

 

 

[TRKLGND]

Just because I wouldn't have bought it doesn't mean there is anything wrong with the truck.  It's your money.  You spend it any way you want.  Just a lot of warning signs for me.  Most guys that spend $3k or more (just a guess) on performance mods don't baby the vehicle.
I hope your right about her "show pony" status and that she serves you well for many miles.