Help with some lt1 tuning tuner pro

**Magoo_oner** · 06-07-2023

So back to the transmission it’s not shifting right sometimes it will shift to 2nd or 3rd but everything is off I know my gear ratio that the tune originally had was for 3:42 now it has 3:08 with a smaller tire so not sure if my shift points are out of wack or if it’s internal issues with the transmission

**steveo** · 06-07-2023

when you change gearing there are all these vss based transmission tables that need to be corrected. you need to do some math and find the percentage difference between old road speed and new road speed and correct those tables. the commercial tool tunercat has a built in tool that does that for you, or you do it by hand in tunerpro.

for example there is a table called up/down shift points and it is in MPH. so if it thinks you're going 30mph and you're actually going 35mph (probably pretty close to reality with that change) then the shift will happen at the wrong time.

**Magoo_oner** · 06-08-2023

Ok hopefully I can figure it out wasn’t there a site out there where I can plug in my gear ratio overall wheel diameter and transmission type and get all of those numbers or maybe I’m making that up i. My head but I thought I heard something like that

**MO LS Noobie** · 06-08-2023

Originally Posted by Magoo_oner

Ok hopefully I can figure it out wasn’t there a site out there where I can plug in my gear ratio overall wheel diameter and transmission type and get all of those numbers or maybe I’m making that up i. My head but I thought I heard something like that

The more I know the more I don't know. If you go to transmission there is this a item name "pulse per mile" that sets your actual speedometer calibration. It is much better if you set your final gear ratio first. Then I take my actual speed from the GPS at least 60 mile-per-hour and then my indicated speed from the speedometer and divide the two and see what percentage it is off. Then take the "pulse per mile" (will be 20,000 or so) and divide it by the same number. In other words if your speedometer reads 66 miles an hour high at 60 it is reading 10% fast, you take your pulse per mile and remove 10% ( 20,000 - 2,000 = 18,000) I hope this makes sense, Jeff

**Magoo_oner** · 06-10-2023

I’m using tuner pro so do I need to input my gear ratio anywhere or is it just those tables that I’d have to tweak for shift points the tune isn’t stock I sent the ecm out years back originally it was from a 94 Camaro but now it’s in a 78 el Camino I can also put up my bin on here if that helps at all

**NomakeWan** · 06-10-2023

There's no gear ratio entry on this PCM. It's just the tables you were told about earlier. Shifting on the 4L60E is handled by speed-based tables. You change the speeds, it'll change the shift points. You have to do some math to determine what speeds you need to use based on what RPM you expect for each gear.

**Magoo_oner** · 06-16-2023

I’m going to just throw this th350 in the car can someone point me in the right direction of turning auto trans functions off or manual on tuner pro to run the th350