Tranny Tuning, Desired Shift time

[94Blazer383]

I am done with the Vette for a while, so its time to start messing with the Blazer again. I was doing some reading over at thirdgen and came across a post about "Desired Shift Time" in the OD hack. I added these tables to my .xdf file and was wondering what some of you guys are running. Or, what is the minimum safe shift time? I would hate to have a stack shift or mess up the tranny.

[94Blazer383]

Looks like I posted in the wrong section. :aniteef: Sorry, I just saw the trans tuning section. I think thats new since the last time I posted here!

[94Blazer383]

ttt

[HaulnA$$]

Moved to proper forum.

[383 silverado]

[QUOTE=94Blazer383]. I was doing some reading over at thirdgen and came across a post about "Desired Shift Time" in the OD hack./QUOTE]


what do you mean by shift time ?

do you mean what rpm to shift at?

if so some people are shifting at about 5200-5500 rpms

[94Blazer383]

There are 3 tables that control the amount of time between each shift. The 1-2, 2-3, 3-4. The shorter the amont of time, in msec, between the shift should be easier on the cluthes. Less slip.

http://www.thirdgen.org/techboard/diy-prom/266357-pcm-control-4l60e-induction-2.html

post 63

[383 silverado]

94blazer383 is that the same haulna$$ in post # 4 ?:think:

sorry i have no clue.:dunno:

i know :offtopic: but i have to ask.

how is the vette doing did you get the bugs worked out of the pcm ?

[HaulnA$$]

There are 3 tables that control the amount of time between each shift. The 1-2, 2-3, 3-4. The shorter the amont of time, in msec, between the shift should be easier on the cluthes. Less slip.

http://www.thirdgen.org/techboard/diy-prom/266357-pcm-control-4l60e-induction-2.html

post 63Huh, I did'nt remember posting that. It was'nt very often that anyone got to correct Grumpy. May he RIP.

Anyway, calibrating the desired shift time is not as easy as plugging in the magic numbers and it shifts perfect. It depends on a lot of other factors like where you base pressure tables are and whether or not you have any mechanical upgrades to your tranny that affect the pressure but I have typically found that at around 150mS you can start to see problems. The desired shift time setting is like BLM's to the tranny side of the code. The PCM uses "Adaptive Pressure Modifiers" to attempt execute the desired shift within the time specified. It will adjust the pressure from the base setting by multipliying it by the modifier to do this. If you just want to firm up the shifts a little for performance and to extend the life of the tranny, you can do it by just decreasing the desired shift time, to a point, but if you really want to get the most out of your tranny then you need to adjust the main tranny tables like the base pressure tables, force motor current tables and the other pressure modifier tables to actually decrease the time it takes the tranny to shift. You also need to monitor the transmission datastream. There is a torque output value as well as force motor current, shift time error, and adaptive modifier values and cells as well as a ton of other good info. You can datalog the tranny data and make adjustments to the proper tables just like you with BLM's and fuel. HTH

[HaulnA$$]

94blazer383 is that the same haulna$$ in post # 4 ?:think:

sorry i have no clue.:dunno:

i know :offtopic: but i have to ask.

how is the vette doing did you get the bugs worked out of the pcm ?That would be me. ;>]

[94Blazer383]

94blazer383 is that the same haulna$$ in post # 4 ?:think:

sorry i have no clue.:dunno:

i know :offtopic: but i have to ask.

how is the vette doing did you get the bugs worked out of the pcm ?

Yup, same dude.

I have have been messing with tuning my truck for almot 2 years. I still dont know a fraction of what he does.

The Vette is running perfect, all the way to 7000 Rpm :burn:

[383 silverado]

Yup, same dude.

I have have been messing with tuning my truck for almot 2 years. I still dont know a fraction of what he does.

The Vette is running perfect, all the way to 7000 Rpm :burn:


one word sweet.

i just love :patriot: muscle cars.