Trans Calibration, what to change...

[LS1_Dragster]

If you put a supercharger or nitrous on your vehicle and you want to help the trans live what would you change in the trans calibration?

I assume you would want more line pressure and there appears to be a few different places like D0704 1->2 pressure adjust, D3801 force motor current (this would up the pressure across the board I think).

Before I waste a ton of time has anyone worked with the trans parameters?

Thanks,

Lee

[SSpdDmon]

You add torque management if you want it to last. LOL

[johnv]

reduce shift times D1108, D1109 and bump the line pressure D0701,D0702,D0703.

and take some torque management out, just enough to give a firm shift.

pretty sure joecar has a tutorial in here somewhere ?

[GAMEOVER]

reduce shift times D1108, D1109 and bump the line pressure D0701,D0702,D0703.

and take some torque management out, just enough to give a firm shift.

pretty sure joecar has a tutorial in here somewhere ?

:thumb_yello: +1 on Joecar's Tutorial

[LS1_Dragster]

I searched for trans pressure and never really came up with anything then I searched for one of the trans parameters and found a bunch of stuff including his tutorial.

Lee

[joecar]

Increase shift pressures, decrease shift times (reduces transitional slip during shifting, and makes each shift firmer)...

and if you have big engine torque, then to increase trans life, increase shift torque reduction (engine pulls timing for about 0.1-0.2 second during each upshift).

Maybe decrease D3801 force motor table (lowering it increases pressure)... but be careful with this table... I would rather turn the PCS solenoid factory set screw in by 1/8th turn than... but try the above things first.

[joecar]

Oh, see this page (http://forum.efilive.com/showthread.php?t=2990) for this thread (http://forum.efilive.com/showthread.php?t=1723).

[Telco]

I would rather turn the PCS solenoid factory set screw in by 1/8th turn than... but try the above things first.

Questions, Joe. First, does a 4L80E have this? If so where might it be found? I can't find it in the shop manuals, probably just missing it. Still trying to work out that clunk on the 2-3 shift, can't seem to get the last bit out. I'm thinking that if I were to mechanically reduce pressure here, I might be able to get it squared away. In the meantime, I'm going to try tweaking the D3801, found what's supposed to be a stock program that has a different D3801 table than mine does. I'm hoping that, since the adjustments to this are 1/8 inch at a time that mine's just slightly off.

[joecar]

Yes the 4L80E has a PCS/TFM solenoid, it plugs into the front of the valve body.

To reduce the 2-3 jerk, do not adjust the screw in the PCS, try this instead:
- reduce the 2-3 shift pressure table in the range where clunk occurs;
- increase the 2-3 shift torque reduction table in that range;
- increase the 2-3 shift time table in that range;
- alter the 2-3 VSS/TPS upshift table in that range;

Is the clunk dependent on temperature range...? If so there are temperature pressure modifier tables to play with.


--> When you say clunk, is it a mechanical/basklash clunk, or is it a very stiff/jerky shift...?


When you modify the PCS (screw) or its table (D3801), you're modifying the pressure for all the shifts, so be careful not to mess up the other shifts.

Hmmm, so your D3801 isn't stock for your transmission...? Yes, try the stock table.

[Telco]

Well, the D3801 stock table has been a bit of a problem. I've pulled several tunes from holdencrazy and they aren't all the same even though they are supposed to be stock. The clunk started as a horribly hard shift, but is now down to a "ker-chunk" sound. Sometimes it's a bit rough. I've messed with the program to death and have gotten it to where it is. Torque reduction is set to 45 percent, D0702 has been as low as 8 with half the fields being 0, and D0706 has been as high as 6-8. I've not modifies the PCS screw, but initially when I was working on this I was only messing with D3801, and was told that this is a bad thing to do. At this point though, I'm thinking that there's nothing left to do. The bummer here is the 3-4 shift is perfect, and the 1-2 shift is almost perfect. I wasn't wanting to mess with them, although I can if I need to.

So if I increase the numbers in D3801, it will soften the shifts, correct? The other "stock" program I found a different table in has slightly higher numbers.

[joecar]

D3801: yes, increasing the values decreases the pressure (softens) everything.

[Telco]

Wow... dropped a very little off, and it changed the trans completely. 1-2 now slips, 2-3 and 3-4 shift almost perfect. I've already tightened the 1-2 shift up using field D0701.

[joecar]

Make sure it does not slip in gear.