Discussion and questions related to the course Road Tuning
when doing a ramp run starting from 2000RPM in the dyno, i use the VCM scanner controls to select the gear i want to do pull on then i lock the converter. sometimes this method will work sometimes it will immediately will down shift. on the street it will always down shift. i know i have to to change some stuff in the transmission to lock in a certain gear.
could somebody guide me where to start.
thanks in advance
Does this vehicle have a manual mode? I've tuned a lot of late model GM vehicles running the 6L80 transmission and in manual mode I can force the transmission to hold 3rd gear. This is useful for tuning however you do need to realise that the transmission will naturally tend to kick down if you're in drive and you floor the throttle at low rpm.
the vehicle has a manual mode. manually i will select 4th gear, then lock the transmission and last lock the TCC. this method will work in the dyno but in the road it will downshift. usually my runs will around 2000 or 2500RPM. i know i can modify some table in the transmission but i dont knoe where to start.
thanks for your reply
Be mindful about forcing the lockup on the converter at high loads, it is designed for cruising efficiency/engine braking not to bear full load motor torque, if that is what you are doing, perhaps that is why you are getting a drop down?
am doing this to to log my timing advance in high load low RPM area. i've successfully locked the converter both in the Dyno and on the street using the vcm scanner. why i failed in the first place? because i was doing it wrong.
the right way is bring up the gear to the gear that you've chosen to do a pull on (using manual mode) then select that particular gear from scanner controls then lock TCC under TCC tab and finally start the pull.