Offroad Trailblazers and Envoys

3.73 to 4.10s.. Tuning PCM to account for it 2003 TB ltz

G80, GU6, GT4, GT5, WTF? This section is for gearing and driveline stuff.

by lukeclement » Tue Sep 24, 2019 12:59 pm

Hey guys, have a 2003 Trailblazer LTZ, it's got the 3.73s with the G80. I am looking at some axles out of a different truck that also have the G80, but with 4.10 ratios. This is good for me, because i'll be running basically 32.5"s here pretty quick. I currently have 31.6"s, and when I hooked up my HPtuners to my truck to change tire size (it has a field for that in my buddies 05 avalanche, so I assumed it would work on my TB), there was no field for that.

So, my question is, what kind of weird tuning will I have to do so that my shift points and all that crap don't get too screwed up? Can I even do this on my year truck? I remember reading that the 02 and 03 years are different from the others. Thanks for any and all info regarding the diff swap.
Posts: 2
Joined: Tue Apr 02, 2019 3:22 pm
Location: San Luis Obispo, CA
Name: Luke
Vehicle Year: 2003
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ G80

by PROSPHOTO » Thu Sep 26, 2019 5:35 am

Years ago, the HP tuner was very limited when it came to these trucks; don't know if that changed. The EBTCM has the ability to alter the tire size, but only up to 30" tires (if I remember correctly). PCMforless (PCM of NC) maybe able to get the computer close (gears),you'd have to contact them you find out.
I downloaded a GPS Speedo app on my phone, and thats what I use as my speedometer since the truck speedometer is off 5-6mph at highway speeds (3.73's w/32" tires)
Posts: 54
Joined: Wed Apr 13, 2016 9:12 am
Location: Long Island, NY
Name: Michael
Vehicle Year: 2006
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ G80

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