My trans builder suggested I need to reduce the duty cycle of the trans but I'm not seeing it in the VCM dashboard. My issue is the 3-2 downshift when coming to a stop when cold. It's a built trans with a billet 2800 RPM stall.
My trans builder suggested I need to reduce the duty cycle of the trans but I'm not seeing it in the VCM dashboard. My issue is the 3-2 downshift when coming to a stop when cold. It's a built trans with a billet 2800 RPM stall.
Post your tune, most likely he means the force motor current table to increase line pressure.
How do I post the tune? I read how at one point but can't remember or find the instructions.
To compensate currently I have the 2-1 and 3-2 downshift MPH low but I don't care for it. I will also ask if force motor current is what he's specifically referring to.
FYI trans builder confirmed duty cycle is the same as force motor current. He's suggesting I increase duty cycle on 3-2 in the RPM range I experience it. I'll share the tune if someone can tell me how.
Here's the tune file.
You can try this and see if it helps. I raised the base shift pressure some for a start. You may not need to adjust downshift pressure, i only have once on a weak tranny. I also raised tcc duty cycle for the stall.
The trans already shifts really strong. It's built by Performabuilt. My concern would be raising pressure would cause it to shift harder and that's what I'm trying to tone down. Mainly 3-2 when coming to a stop. When cold the tires would chirp until I moved the downshift MPH way down. So low in fact it's a big gear change to drop from 3-1 at a few MPH at light throttle i.e. traffic or parking lot. Billett 2800 RPM stall and 4.10 gears in 1/2 ton L33 LS. I'd like to get the 3-2 and 2-1 downshift MPH back to where it was stock. The builder suggested adjusting "duty cycle" in that throttle range which I've translated in HP to Force Motor current. I'm just not sure which way to go. I would assume lowering the Force Motor current would soften the downshift and upshift in that throttle range but I'm not sure. It upshifts a bit strong under light throttle anyway. It's not terrible but if fixing one helps the other great. Above 40% throttle and up it shifts just the way I like it, quick and firm but not bone crunching.Originally Posted by 04silverado6.0
Anyway I appreciate the help and you jumping in! I just want to be sure it's the right way to go and you have all the proper info. I can certainly try it and put it back to what I have now as well.
Thank you!
Here is the same file with a reduction in pressure on the 3-2, i would be careful reducing pressure.
Thanks 04. I see you pulled pressure in the lower temp range on 3-2 modifier, increased max trans pressure to 96, and bumped the TCC duty cycle/pressure. I'm going to upload it with my downshift speed back to stock and see how it goes in a few. I was thinking about doing exactly what you did but the builder suggested the duty cycle/force motor current adjustment first and then pulling pressure in the modifier second. I just wasn't sure what was the right way to go on the force motor or how much.
I will let you know how it goes!
Thanks again.
Hey did you ever get this sorted ? I?m going through the same shit with my performabuilt trans . Sorry I know it?s an older thread
Always best to start your own thread. Post your .HPT file and we can take a look. The partial info. on the force motor current in this thread is incomplete. In order to lower the line psi via FMC, you need to raise the FMC number. As the FMC goes up, it lowers the line psi.
I like a tire barking shift every time i pull out of the walmarts.
Got to have 2" dual exhaust, with no mufflers, into 5" slash cut chrome tips so it sounds like firecrackers in a metal garbage can whenever you git on it.
Quote " I just want to be sure it's the right way to go and you have all the proper info."
Here is some more info. You should ask the builder about the accumulator springs and or bores. You may have broken accumulator springs. 3-2 is really bad for breaking and the 2-1 not far behind. Mechanical force motor change is the way to go If the springs are not broke. Pull the pan. turn the screw on the rear of the force motor counter clockwise an 1/8 of a turn. Its a T-15 torx. Its not always a tuning issue. Of course this is just my opinion.
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