Hey Guys, trans shift questions

[04SilveradoMykk]

Hello,

I've got a 4L60E behind a carbed 350, the trans is the original 2004 4L60E using the 2004 Silverado 4.3L/4L60E PCM to control it. The only sensor inputs going to the PCM are crank position, throttle position, ECT & oil pressure. The only sensor missing is the MAP sensor, and that can easily be put back inline if the trans needs it for one reason or another.

the 4L60E has a 2800-3200rpm stall converter, and no matter where I set the shift time I always seem to get a RPM spike in between gears. It happens not only on upshifts but downshifts too

Any one have any thoughts of how to eliminate the RPM spike and make a smooth transition from one gear to the next?

Uploaded is the current tune on the PCM used for the trans, ignore the engine settings (or perhaps something on the engine side of the tune needs to get modified for the trans?) because the engine is carbed & mechanical ignition.

Thank you, Cheers ~Mykk

[schardbody]

i would start by removing all torque management. then lower shift time tables. your pressure settings look very low too. do you have a kit in the trans or stock??

[04SilveradoMykk]

i would start by removing all torque management. then lower shift time tables. your pressure settings look very low too. do you have a kit in the trans or stock??

Factory internals, no shift kit, no vette servo

[schardbody]

try more pressure, less shift time, and no TM.

[04SilveradoMykk]

try more pressure, less shift time, and no TM.

More pressure as in the FMC table?

[schardbody]

for starters yeah. i'd multiply them all by .97 this will raise line pressure across the board. then start playing with individual shift pressure to fine tune.

[04SilveradoMykk]

Thanks for your help schardbody, TM was the cause of my RPM spikes in between gears. I zeroed out the tables and no more issues. I also increased line pressure but didn't notice any changes.

[schardbody]

to increase pressure you have to LOWER force motor tables. or to fine tune each shift INCREASE the pressure tables for that gear.

[04SilveradoMykk]

to increase pressure you have to LOWER force motor tables. or to fine tune each shift INCREASE the pressure tables for that gear.

Understood