08 pontiac g8 wot shifts

[rollincoal6.6]

Hey everybody.I got the g8 tuned up with efi live.car runs great but its got a couple shifting problems.the trans its an auto 6 sod. 1-2 shift is great.but from 2-3 and 3-4 that's when it wants to redline the gears.i put 3.45 gears in it.I did some research on it but didn't eactly understand what I should start with ( efi live newb).any. help would be great.thanks jon

[Taz]

Hello Jon,

Post your original, unmodified ECM & TCM tunes, along with a description of any changes to tire size and gear ratio. With this information myself, or another Forum member, should be able to help out.


Regards,
Taz

[Patrick G]

Your trans shifts off mph primarily. The swap from 2.92 gears to 3.45 gears means you'll now need to reduce all shift mph tables (don't forget the TCC tables too) to 85% of their original value. If the trans wants to shift 1-2 at 50kph with stock 2.92 gears, it will now need to be 42.5kph to shift properly with 3.45 gears. Don't forget that the motor will rpm faster with the gears so you may need to command the shifts even sooner than the standard percentage reduction. Datalogging will tell you for sure, but a straight 85% of the original shift point values will get you in the ball park.