8L90E triple disk pressure control

[gerry_foster]

Hey folks! I'm a long time Mechanic and fabricator/shop owner here in Ontario, Canada.

So, I have a very odd ball personal build, 87 R10 suburban (Beatrice the Burb) swapped in an LQ9/243 heads/BTR stage 2 truck/TBSS intake/92mm TBC/50LB injectors.

this is where it gets weird....I have been after efficiency since planning this swap, so i opted for a 5th gen 8L90E trans...

this is uncharted waters, and with Zero Gravity performance and PCS, they have worked out that the PCS TCM2600 interface can drive the 5th gen 8L behind what ever motor you want.

this interface takes TPS and RPM and outputs the Torque signals the Gen 5 needs to function. There is a spreadsheet that allows user input of engine torque in cells using RPM and TPS. ill attach a screen shot of this table.

So the combo has been great for 1000 miles on the stock new GM converter/trans, very nice working combo.

Just got the Yank 2800 Pro Truck Billet triple disk converter and installed it over the weekend, and this is where i need some help....

The Yank is not happy with the stock single disk TCC line pressure of 20 ish PSI, these converters like higher 75 + psi to lock up as we all know, but this is where I dont know how to properly get the 8L TCM to apply this higher pressure. Ill attach the as found tcm file, modified tcm file with raised pressures and stall parameters, and a quick log of the transmission.

the issue is the tcc line pressure ramps in pretty slow, and only builds to 25-30 psi, this translates into an on/off/on/off feel when the TCC is trying to lock. if i command the TCC lock in hp scanner special functions, it shows 594 psi TCC line pressure, and its gives a great FIRM lock up and holds great! So i feel the new converter is mechanically sound, its just finding the right tables to modify to get this Yank happier, higher TCC line pressure.

I'm no tuner, just a guy who dabbles, I use a reputable establishment in North Carolina to make the major changes in most of the swap stuff i deal with, they are fantastic, but they are not quite sure where to go on this combination.

Can anyone help with experience in this 8L world? the tables seem quite different to the 6L's and there seems to be very limited info out there on triples with 8L's yet.

end of the day, i'd like to achieve a 75 PSI, quick ramp up TCC line pressure, I like a firm lock up feel, not this factory slipping in and out methodology GM now uses, and we all have seen how these 8L's are having lock up issues and fluid problems according to GM. this is using the crazy $$ Mobil 1 LV fluid, and as stated above, there were no issues before swapping to the yank.

Log file is pretty short and the 1st part you will see the TCC line pressure ramp up, and the TCC slip speeds fluctuating -/+ which follow the feel i get of on/off/on/off, later in the log i command TCC and you see it by the 594 psi TCC line pressure. I didn't want to drive any distance and harm the new TCC clutches

Thanks in advance. Gerry

[gerry_foster]

Hey folks! I'm a long time Mechanic and fabricator/shop owner here in Ontario, Canada.

So, I have a very odd ball personal build, 87 R10 suburban (Beatrice the Burb) swapped in an LQ9/243 heads/BTR stage 2 truck/TBSS intake/92mm TBC/50LB injectors.

this is where it gets weird....I have been after efficiency since planning this swap, so i opted for a 5th gen 8L90E trans...

this is uncharted waters, and with Zero Gravity performance and PCS, they have worked out that the PCS TCM2600 interface can drive the 5th gen 8L behind what ever motor you want.

this interface takes TPS and RPM and outputs the Torque signals the Gen 5 needs to function. There is a spreadsheet that allows user input of engine torque in cells using RPM and TPS. ill attach a screen shot of this table.

So the combo has been great for 1000 miles on the stock new GM converter/trans, very nice working combo.

Just got the Yank 2800 Pro Truck Billet triple disk converter and installed it over the weekend, and this is where i need some help....

The Yank is not happy with the stock single disk TCC line pressure of 20 ish PSI, these converters like higher 75 + psi to lock up as we all know, but this is where I dont know how to properly get the 8L TCM to apply this higher pressure. Ill attach the as found tcm file, modified tcm file with raised pressures and stall parameters, and a quick log of the transmission.

the issue is the tcc line pressure ramps in pretty slow, and only builds to 25-30 psi, this translates into an on/off/on/off feel when the TCC is trying to lock. if i command the TCC lock in hp scanner special functions, it shows 594 psi TCC line pressure, and its gives a great FIRM lock up and holds great! So i feel the new converter is mechanically sound, its just finding the right tables to modify to get this Yank happier, higher TCC line pressure.

I'm no tuner, just a guy who dabbles, I use a reputable establishment in North Carolina to make the major changes in most of the swap stuff i deal with, they are fantastic, but they are not quite sure where to go on this combination.

Can anyone help with experience in this 8L world? the tables seem quite different to the 6L's and there seems to be very limited info out there on triples with 8L's yet.

end of the day, i'd like to achieve a 75 PSI, quick ramp up TCC line pressure, I like a firm lock up feel, not this factory slipping in and out methodology GM now uses, and we all have seen how these 8L's are having lock up issues and fluid problems according to GM. this is using the crazy $$ Mobil 1 LV fluid, and as stated above, there were no issues before swapping to the yank.

Log file is pretty short and the 1st part you will see the TCC line pressure ramp up, and the TCC slip speeds fluctuating -/+ which follow the feel i get of on/off/on/off, later in the log i command TCC and you see it by the 594 psi TCC line pressure. I didn't want to drive any distance and harm the new TCC clutches

Thanks in advance. Gerry

Realizing now this should be in GM V8 transmissions.....sorry

[gerry_foster]

Solved the mystery!

I was using an older version of Editor, updated to the newest version, and it also added a new TCC desired pressure table! I did not have access to this in the older version....

this table yeilded results when changed, unlike the TCC gain and TCC offests.

Ill attach my new adjustments if others happen to run into this hiccup with aftermarket stall lock up surging and low pressures.

[sevinn]

Glad you found the table! I had no idea that pcs was working on that, I'll have to check it out!

[GHuggins]

You have to shift that table several rows to the left to fix this issue then interpolate the rest of the rows back to the max setting column.

[Ben Charles]

Nice!! Using the same controller very soon on a Big block!!