Got my Tune On!

[DaveO9]

Took it to the local tuner here in Vancouver, WA I've used for years. Old School EFI - he's big in the OBD I world, but also does a great job with the newer stuff, too. GM only.

Did minor mods to both ECM and TCM.

ECM:
- DOD off
- Axle protection via spark and via ETC off
- Tip-In commanded torque reduction off
- Clunk reduction via spark and via ETC off
- Traction control via spark and ETC off
- Power hop control via spark and fuel off

TCM:
- TCC prevented in all but 5th and 6th
- Shift tables modified to provide higher shift points in most situations.

Initial impressions very good. Haven't noticed any negative impacts to drivability, just positive - mostly just notice the higher shift points. This rig has 3.08 gears - the changes seem to have lessened the gear hunting.

Any thoughts on the changes? He has a 30-day change policy so I should be able to bring it back if I want anything additional (or anything turned back on). Not having the protection stuff doesn't bother me too much; I don't drive it like a race car. I am a little curious about turning off the traction control?

 

[blackelky]

Sounds pretty standard. I have the 3.08 gears too they're pitiful i have to get higher gears to really wake this thing up.

 

[Marky Dissod]

Traction control via spark and ETC off
... a little curious about turning off the traction control?

He didn't 'turn off the Traction Control.
He turned off the spark reduction and the electronic throttle reduction that occur DURING the brake application.
Next time you encounter wheelspin, it's up to you to relax the throttle, or not, while the traction control brakes are applied.

Sounds pretty standard. I have the 3.08 gears too they're pitiful i have to get higher gears to really wake this thing up.

Depending on usage and preferences, 3.23, 3.42, or even 3.73 would:
improve city MpG
cost little to nothing in terms of highway MpG
and REALLY wake it up.

 

[blackelky]

He didn't 'turn off the Traction Control.
He turned off the spark reduction and the electronic throttle reduction that occur DURING the brake application.
Next time you encounter wheelspin, it's up to you to relax the throttle, or not, while the traction control brakes are applied.

Depending on usage and preferences, 3.23, 3.42, or even 3.73 would:
improve city MpG
cost little to nothing in terms of highway MpG
and REALLY wake it up.

I have to change front diff gears as well too right? Might just pull a rear and front from the junkyard

 

[Marky Dissod]

I have to change front diff gears as well too right?
Might just pull a rear and front from the junkyard.

To keep 4WD, yes, both front & rear differentials must be the same gearing.

Any thoughts on the changes?
He has a 30-day change policy so I should be able to bring it back if I want anything additional (or anything turned back on).

If you don't Tow / Haul AT ALL, maybe ask him to write the Tow / Haul shift map so it behaves more like a Performance Mode?
I don't Tow / Haul AT ALL, my 'Normal Mode' is only a wee bit more assertive than GM's Normal, and then only at 'more fun' throttle angles.
But when I press the Tow / Haul button, it shifts like someone's bleeding out and I'm driving them to hospital.

 

[DaveO9]

He didn't 'turn off the Traction Control.
He turned off the spark reduction and the electronic throttle reduction that occur DURING the brake application.
Next time you encounter wheelspin, it's up to you to relax the throttle, or not, while the traction control brakes are applied.

Depending on usage and preferences, 3.23, 3.42, or even 3.73 would:
improve city MpG
cost little to nothing in terms of highway MpG
and REALLY wake it up.

Ah, that explains it. Understood and that makes me feel much better. Yeah, the tuner told me on some of these changes, "now you're the manager of this system, instead of GM." Thanks for the clarification.

To keep 4WD, yes, both front & rear differentials must be the same gearing.

If you don't Tow / Haul AT ALL, maybe ask him to write the Tow / Haul shift map so it behaves more like a Performance Mode?
I don't Tow / Haul AT ALL, my 'Normal Mode' is only a wee bit more assertive than GM's Normal, and then only at 'more fun' throttle angles.
But when I press the Tow / Haul button, it shifts like someone's bleeding out and I'm driving them to hospital.

Sounds fun and I'd consider it, but I'm actually going the other way - I want to get this thing more tow-capable, not less.

Time now to start planning for the re-gear project. Will have to decide if I want to get full axle/diff assemblies off a part-out/junk yard or have a shop change out ring and pinions. Leaning towards the part out. Have even considered buying a part out rig myself. Also have to decide on 3.42 vs 3.73. 3.73 would be nice, but it seems like 3.42 would be much easier to find if going the part out option.

 

[Marky Dissod]

... actually going the other way - I want to get this thing more tow-capable, not less.

Time now to start planning for the re-gear project.
Will have to decide if I want to get full axle/diff assemblies off a part-out/junk yard or have a shop change out ring and pinions.
Leaning towards the part out. Have even considered buying a part out rig myself.
Also have to decide on 3.42 vs 3.73. 3.73 would be nice, but it seems like 3.42 would be much easier to find if going the part out option.

Smart programmers can edit GM's Tow / Haul table to improve the powertrain's durability AND longevity, regardless of axle gear.
That said, I think 3.42 should have been the laziest OE gear.

So far as I know, 3.42 was for the 1500 suvs Tow-iest / Haul-yest options; yes, 3.42 will be statistically easier to find first.
If you're gonna tow over 7,000lb, 3.42 is good enough for GM - but I'd recommend 3.73, or even 4.10, depending on the trailer's aero drag.
More axle gear = longer lasting engine and transmission - plus your MpG while towing might actually improve.
Obviously 4.10 would cost highway MpG while unladen. Both 4.10 and 3.73 would improve metro / urban MpG.

clears throat
3.73 - and occasionally, even 4.10! - were available for 1500 Silvierados with 5.3L V8s (not 6.0L or 6.2L).
So even if there ain't many out there, they're out there.

 

[DaveO9]

Smart programmers can edit GM's Tow / Haul table to improve the powertrain's durability AND longevity, regardless of axle gear.
That said, I think 3.42 should have been the laziest OE gear.

So far as I know, 3.42 was for the 1500 suvs Tow-iest / Haul-yest options; yes, 3.42 will be statistically easier to find first.
If you're gonna tow over 7,000lb, 3.42 is good enough for GM - but I'd recommend 3.73, or even 4.10, depending on the trailer's aero drag.
More axle gear = longer lasting engine and transmission - plus your MpG while towing might actually improve.
Obviously 4.10 would cost highway MpG while unladen. Both 4.10 and 3.73 would improve metro / urban MpG.

clears throat
3.73 - and occasionally, even 4.10! - were available for 1500 Silvierados with 5.3L V8s (not 6.0L or 6.2L).
So even if there ain't many out there, they're out there.

Thanks for the info. I'll start researching the 3.73 option. On other threads I've seen that there's also a possibility of upgrading the rear end to a 14 bolt semi-float that came in 2wd Esky's and Denalis, but it sounds like 3.73 wasn't an option for those - I'd have to change out ring and pinion too. I think I'll focus more on going to 3.73 than the 14 bolt carrier.

 

[mikeyss]

07-08 Avalanche LTZ and Suburban LTZ with the L76 6.0 had 4.10 gears and the 14 bolt differential. Those are hard to find. Also 2010-1013 Silverado with the L9H 6.2 had either 3.42 or 3.73 as optional.

 

[MrMonte]

I found a 6 lug 14 bolt 4.10 posi at a local junk yard. Removed the drum brakes & grabbed some disc brakes all for $125 then installed in my 1999 Suburban. Also pulled 3.73 gears from a low mileage 10 bolt Escalade for $50 for my 73 Camaro build.

For the Suburban the 4.10 gears were better than the 3.73s.