4L80E Shift firmness

[Jon01]

I'm trying to firm up the shifts on the 4L80E in my swap truck. It shifts very nicely when in SD mode but as soon as I re-enable the MAF it loses the firmness - I assume due to the line pressure following the tables?
I'm hesitant to add too much shift pressure as I don't know what's safe/not, this is the first -80E I've messed with but it'd sure be nice if this thing would shift somewhat firm.

Does anybody have any input?

Combo:
LQ4
243 heads
Tick cam
FAST 90/LS2 90
Revmax 3700
Here is the current tune:

Truck - MAF 10.hpt

[Mike1995]

Can you copy the Performance tables over to the Normal tables?

[MikeOD]

When you're in SD mode, it's shifting at max line pressure all the time (there's a setting you can change so it won't do that). That means your full throttle shifts that should already be at max pressure probably feel the same, but your part throttle shifts feel much firmer in SD mode.

When I had 4L80E truck, I copied the line pressure tables from performance mode (tow/haul mode) over, and then increased them a little from there, I also decreased the shift time a little bit and it wound up shifting very nicely.

[Russ K]

I haven't seen a max line pressure DTC enabled since 2001. The newer trucks don't have that table, and I just did a SD tune on a 2007 6L truck with the Gen III pcm and no shift pressure issues. On the older vehicles with the max pressure DTC enabled, in SD mode with stock shift pressures, the trans shifts are very hard.

As for the shift pressures, first 0 the the 100 psi column of the force motor table and change the max pressure field to 96 (stock is 90). Then starting with the stock shift table highlight the 0 ft lb column & enter 0 if not already 0 stock. Now highlight the 640 ft lb column and enter 20, then click the left upper corner and click interpolate between horizontal bounds. Copy the table, then undo all changes (make sure the table is back to stock). Next highlight the table > paste special > add. So now you added 0 psi at 0 ft lbs, and 20 at 640 ft lbs (note that the editor will normally limit the pressure to 96). If firmer shifts are desired, then instead of the 0-20 psi method, go in 0-10 psi increments until the desired firmness is reached. On most A4 trans, I firm up the 3-4 shift more than the 1-2 & 3-3. On the 4L60-70 trans that I install the Vette 2-4 servo, less 1-2 shift pressure is needed.

Russ Kemp

[DWC]

Russ,
I'm tuning a 05 Silverado 6.0 4L80 and the scanner shows a loss of spark between shifts, any help would be appreciated.
Regards,
DWC

[Russ K]

Russ,
I'm tuning a 05 Silverado 6.0 4L80 and the scanner shows a loss of spark between shifts, any help would be appreciated.
Regards,
DWC

Ok, on your truck the Torque Reduction> Normal table is zeroed as stock. So what I do is go to Torque Management>General>Spark Retard>vs Torque Reduction and to reduce the upshift torque reduction by 50%, multiply this table by .5. If you want no upshift torque reduction, then 0 this table.

Russ Kemp

[DWC]

I'll post the tune and a scan this afternoon, already have this table @ zero sir. Thanks for getting back with me.

DWC

[03Sierraslt]

As for the shift pressures, first 0 the the 100 psi column of the force motor table

Russ Kemp

What does this do? My force motor table is scaled normal except for the 100 column it has 1245 in it. I have no shift issues just trying to gain knowledge. Is that basically not allowing it to command 100 for line pressure?

[Russ K]

What does this do? My force motor table is scaled normal except for the 100 column it has 1245 in it. I have no shift issues just trying to gain knowledge. Is that basically not allowing it to command 100 for line pressure?

That is so the force motor won't drop the line pressure if more than 96 psi shift pressure is requested. You don't scale the force motor table as it can cause a P0748 code.

Russ Kemp

[03Sierraslt]

I guess I should reword that, my table is untouched. I just the numerical values decreased across except for the last 100 column.

[Russ K]

I guess I should reword that, my table is untouched. I just the numerical values decreased across except for the last 100 column.

Ok, still not the right way in firm up the shifts. Just follow my procedure, very easy to do. Plus you can firm up the individual shifts.

Russ Kemp