TOPIC: 2018 GMC Sierra 1500 6.2L V8 - Starting from scratch

Looks great for your FIRST!! My first groove cut looked worse. Too deep in 3 spots. Too wide, and overall not consistent in shape. Guess what?! That first groove job is STILL on my 2000 Ram 5.9L because it worked so well! Do your best in following the manual, take your time. The groove shape will do the rest!
For your second groove, id recommend going one groove cut closer to the throttle shaft but not too close! Feeling comfortable grooving closer to that HARD piece of metal takes time, though it pays off when you get the results from a bigger groove waveform!!
Great job on keeping us posted, and remember for your beautiful GMC truck, the throttle body will require more room than you think you need for the swing of the throttle plate to find the proper idle (only GM's) so cutting the groove farthest away from the idle position, the smoother the idle after the mod. Here's a picture of a groove i did. I tried to get as close to the plate shaft as possible.

TB about to be grooved (but it will have to wait until I get back! >:/ )

Questions:

GM TB needs the card jammed in the top of the TB to achieve the correct position. I can see this as the plate opens to nearly the very end of the body. The card holds it to the proper position. For my specific application (TB) - Does this look like it’s properly positioned?

Also, the TB has a bit of a lip, sort of a taper towards the engine side of the TB. Has anyone had any experience with this impeding the groove??

The final shot shows the plate too far opened to be of service. What you'll find if you cut it here is the groove will be too far downstream. You will need to move it 1/8" (+/-) more closed.

And the Groove on this TB will appear mis-shapen, but don't worry. It'll work just fine.

The main issue with this type of throttle body is trying to rush through the conditioning process! So, take your time and don't be surprised if you have to re-Groove it. It's good practice! And that's what'll happen if you move it too far to the closed position.

Make SURE the plate is LOCKED into position, as these tend to let go and cause issues with the Groove shape.

Words to the wise...

Agree with Ron on the plate being too open (it’s too bad the TB is so clean - this is when carbon is your friend here), and the spacing away from the plate comes from the ANGLE of the bit to the bore. Remember the top of the bit needs to touch the plate before you cut into the bore - it’ll take a minute for you to “feel” the right way to hold the tool...and you SHOULD take that minute.

The last picture posted below your post showing the bit against the plate doesn't seem to far back to me. In my experience, i find it better and faster for both the Gadgetman and customer to cut the groove as far back as possible. Removing everything again, throttle, filling in with jb-Quick, waiting to harden then sanding and re-cutting groove takes time. I haven't seen diminished results from far back cuts yet on GM's, actually very positively impressive ones! However it is better to get closer to the idle position to tap into even more power potential, but I've seen this little groove do wonders no matter where it's placed, and surprisingly no matter how it looks. Aim for perfection, but don't worry it doesn't turn out that way. Put the throttle on anyway and prepare to be amazed! Just jump in there Andrew! This is truly a God sent gift to us. Have fun, and read the manual!!

This GM throttle didn't have issues with idle


These needed to be re-cut

Thanks for the tips! I surely do appreciate it! My goal is have it grooved by this Saturday.

In the meantime, between all the craziness and the short time I've spent at home; as I mentioned, I changed the oil and did the PCV delete. Recently applied Ron's amazing Snake Oil. The engine runs smoooooooth. I tried to put a SO Automatic Transmission application, but guess what!! There is no filler/dipstick on this tranny! It's sealed. I'll have to go underneath and find the plug and put the application in that way. >:-/ I did put an application in the cooling system. Also, put in a SO fuel treatment application in a new tank of gas.

Here is a simple graph, since I got the truck.

Thus far, with all the modifications chronicled in this thread:

Starting March 2019 and 4510 miles driven:

Highest - 14.8 mpg
lowest - 11.8 mpg
Overall average - 13.5 mpg

The optimistic DIC readout in the truck lists a high of 18.2 mpg; and 15.6 mpg average. I've noticed that at every modification I get a spike in mpg and then it settles back to the 13 mpg range. Shenanigans!!

I'm planning on having it grooved and SO treatment to tranny and diff by this weekend. Then I can concentrate on the EFIE!

I should post my fuel tracking app's graphs to show that while fuel consumption fluctuates, the range has narrowed since EFIE installation.
I'm glad you took my advice on using a fuel tracker app - they're better than pen and paper in that they do the calculating for you, and then let you see a graph
you're still in the big move benchmarking phase - once you have all of this accomplished, you'll start to get the real data and be able to fine tune.

and once you find what is making the computer default back to that 13mpg (I suspect EFIE will help narrow that down), you'll be able to fix that and get what the truck/powertrain is truly capable of. (Don't overlook tire pressures!)

I've finally grooved the TB! I broke through several times, the TB is very thin at points. The groove looks like a total hatchet job, but it's done. Actually, the JB Kwik is curing as we speak, from the points where I broke through. I've regrooved the JBK parts and STILL some light shone through. This third time should be the charm. Planning on installing it this evening (might have to wait until next week on my days off, though

I can't remember if it has ever been addressed, but the portion that broke through on the ECU side had a ton of shavings. I took it apart to clean it out. I'm thinking all those shavings could have an impact??



I took some compressed air and a small brush to get as much of the shavings away from the circuit board and gears.

Some JBK repairs and regroove, from the second application. Third application is curing now....

if "breaking through" creates a pathway for air to enter the intake tract through the throttle motor location, yeah, that's a bad thing.
And as far as aluminum shavings in the motor's gearing, that's probably not great either. Then there's the TPS electronics....again, not good.
You've got all of this cleaned up, I hope.
The pics show significant "cut through" from what I can tell - perhaps you need to address your technique or (and I hope this isn't the case) step down a bit size.
Also, you do still have your factory TB, right?

Yeah, I think I got it all out/cleaned up.

Here’s a shot of the underside where it broke through:



This is a new TB from Rock Auto. The original is still on the truck. I wanted to be able to go back to stock if things went south!