Transmission tuning...

[Six_Shooter]

I'm about ready to try some transmission tuning.

The main patient is using a '7060 and a 4L80E, but another patient is using a '7427, and a 4L60E.

Looking at the $85 XDF there are two tables for shift, "Normal Mode Upshift/Downshift Vs. MPH Vs. TPS" and "Performance Mode Upshift/Downshift Vs. MPH Vs. TPS." I would suspect these two tables are what is the main control for when the tranny shifts, based on TPS, but the numbers in th etable are not defined as something that I can relate to. When I first looked at them I though that a higher number would mean delayed or higher RPM shift, but then looking deeper into the tables, the performance mode table has some lower numbers than the normal mode table.

I'm going to try and find some information I vaguely recall seeing a few years ago, but in the mean time, anything you have, lets get it in this thread. :D

[EagleMark]

I'm not sure how it works in $85. But in $EE LT1 4L60e has those 2 tables and performance mode is activated by a switch only available in Trans Am. It is a button on shifter but it can be added to Camaro, Corvette and B body LT1 with a switch that sends a ground to wire on PCM. I'll include the writeup in a txt file that says it may be possible in others.

If all paremeters are in the $85 XDF the one I found to make a big differance was shift times. If you look at shift times in performance mode they were all 0, but in regular mode had varied times. I had changed the times to 0 and was a much firmer shift and tranny temps went down. Could actually feel shifts like a truck or performance car instead of one big slush...

Changing shift points MPH can be very tricky. I tried this and thought was good till I datalooged and saw at highway speeds trans was shifting 3/4/3/4/3/4 so I turned and went home and got a tranny hot error code... to many other varibles to just make one table change I found. I don't know if it's possible for you to take entire trans table from a $EE but I ended up starting with a caddy 1994 V4P RPO towing option trans bin and it was great start, had raised shift points and capable of downshifting when WOT at speed where stock bin would not. That and the shift times were all I needed to turn the Buick Roadmaster big slush box to an actual trans shifting gears at higher RPM like a performance car or truck feel.

[dave w]

I was given this Excel spreadsheet, I hope helps.

dave w

[EagleMark]

Wow that is cool! There is one in the $EE info thread for doing speedo changes for gears and tires for LT1 but no where near as detailed as this. :thumbsup:

[EagleMark]

When looking through the $85 yesterday I found some hacks and will attach one here. It's BAMY, Line 4051 starts transmission and the performance stuff starts at line 4474.

I'm trying to figure out the flags section of that XDF. Some are easy to find but others seem to be wrong, while many are missing...

EDIT: Removed hack as it was not $85 but $D8...

[EagleMark]

It looks like all the hacks in zip marked $85 are $D8 so not sure this is applicable. No wonder I can't figure out error codes... anyone have a $85 hack ?

BCC Find shows BAMY to be same PCM...

EDIT: I do have 2 $85 hacks if you need them.

[pavement pounder]

I doug up this old threat just to know if you where able to set the performance mode to 0 on the 16147060 4L80E program.
And how does it shift ?

[EagleMark]

Better be more specific to which parameter. I just looked and see "Performance Mode Upshift/Downshift Vs. MPH Vs. TPS " So no! This is MPH.

The table "Shift Time vs TPS" is in msec so lower here makes the shifts quicker. I've been playing with tranny tuning quite a bit lately and you can zero this table. But when data logging it still takes .200 to shift so it seems this is as low as it needs to be set.

But if this is like newer OBDII systems the "Adaptive Pressure Modifier Vs. Shift Time Error " would also have to be zeroed out or it will just learn out the change. Problem is that table does not look correct at all in the definition?

Pretty cool PCM and we have a good dissasembly, just no one has ever spent any time including more items.

[buddrow]

Dont mean to butt in, but the reason u r seeing lower numbers is due to the Pressure Control Solenoid is PWM controlled and the lower the current/more off time, the higher the line prssure. Resulting in firmer quicker shifts. If u have any questions i may be able to help. I havent tuned any trannies yet, on my list of things to do, but I have 20yrs as a trans tech and now how the inner workings operate.

Anywho, lowering the pulse width to the PCS will make firmer/quicker shifts but take it easy. Too much line pressure can be as bad as not enough, you will break things. Remember u want quick and firm not holy crap I just s

[buddrow]

You are seeing decsending values because the Pressure Control Solenoid operates an varying current to adjust line pressure. If ur close to 1.0Amp then line pressure is low. The closer you get to 0.1amps the higher line pressure will be. Just be careful and dont go to low as you WILL break things. The pulse width lowers during the shift so as not to "bang" during the shift. Remember, you want quick, firm shifts but NOT harsh shifts. HTH

Bud

[EagleMark]

Please butt in! :thumbsup:

But I'll probably start another thread with some real questions as to how my tuning results are working, or not working, and whats safe pressure stuff etc...

[buddrow]

Ok I'd be happy to help if I can.

[pavement pounder]

Thanks guys,
I will play with it and see what happens.
Please do butt in, all info is more then welcome, don't need to reinvent the wheel again :thumbsup: