Built 4l60e (RPM L7) - rebuilt and FTI 3800 hard hit converter - tune help

[madmann26]

I need some help fellas,

Long story short, my 17 month old RPM L7 trans spit its guts up. It broke the overrun hub and the rear drum splayed open and started cutting into my case. It did have a firmer-than-firm 1-2 shift, which according to various sources, this is what broke the overrun hub. It was rebuilt by a local guy (new clutches/steels and fixed the accumulator so it doesn't hit 1-2 so damn hard) and the converter was cleaned by FTI and restalled to a 3800 hard hit converter. The 1-2 shift is a lot more comfortable now.

Moving forward,

I have 2 issues.

1. While cruising, the converter is locked. If I depress the accelerator a little to pass someone/something (not forcing a kickdown), the converter unlocks and I see about 600-700rpm of TCC slip in the logs. When it's locked, there is 0rpm displayed and sometimes a negative number.

2. 2-3 shift issues. When shifting from 2-3 at 75% or more throttle, it flares or slips. I don't know how to fix this.


I suspect both of my issues may be pressure related in the tune but I don't want to get overzealous and have to pull it out again for a rebuild. I have been making some adjustments in the force motor table and it feels like it's helping but again, I don't want to get overzealous with it.

The converter, is loooooooooooose. Very loose, which I like.

I'm attaching the tune for review and assistance.

Thanks in advance

2006-sierra-sd.hpt

[Jason B]

I need some help fellas,

Long story short, my 17 month old RPM L7 trans spit its guts up. It broke the overrun hub and the rear drum splayed open and started cutting into my case. It did have a firmer-than-firm 1-2 shift, which according to various sources, this is what broke the overrun hub. It was rebuilt by a local guy (new clutches/steels and fixed the accumulator so it doesn't hit 1-2 so damn hard) and the converter was cleaned by FTI and restalled to a 3800 hard hit converter. The 1-2 shift is a lot more comfortable now.

Moving forward,

I have 2 issues.

1. While cruising, the converter is locked. If I depress the accelerator a little to pass someone/something (not forcing a kickdown), the converter unlocks and I see about 600-700rpm of TCC slip in the logs. When it's locked, there is 0rpm displayed and sometimes a negative number.

2. 2-3 shift issues. When shifting from 2-3 at 75% or more throttle, it flares or slips. I don't know how to fix this.


I suspect both of my issues may be pressure related in the tune but I don't want to get overzealous and have to pull it out again for a rebuild. I have been making some adjustments in the force motor table and it feels like it's helping but again, I don't want to get overzealous with it.

The converter, is loooooooooooose. Very loose, which I like.

I'm attaching the tune for review and assistance.

Thanks in advance

2006-sierra-sd.hpt

You're going backwards on the force motor numbers. Lower numbers raise the pressure.
Should go back to stock with it.
Your Base Shift Pressure vs Torque vs Gear - Normal is way up. Hard to say whats going on because you raised this pressure up, but then lowered it with the force motor table!

As for the 2-3 shift, very common problem to feel that way with a loose converter below the stall speed. Not good if it does it above the stall speed. The 2nd band needs to release while the 3-4 clutch comes on. A lot needs to be checked to figure out why it's doing this. There are things that someone who knows about transmissions can do to fix that but very few people know ALL the things you can do.

I'd suggest adjusting the pressure tables properly to begin with before you burn it up again.

HPTuners help

Force Motor
These values are the calibration of the transmission force motor (pressure control solenoid) versus desired line pressure and transmission temperature. The force motor is a relief valve that requires a current to reduce line pressure, the higher the current the lower the resulting line pressure. It is not recommended to change these values unless you have modified the transmission pressure control solenoid or are experiencing trans slip under heavy load. If you increase the Max Line Pressure constant, you may have to set the values in the 100 column to match (or be slightly lower) than the 96 column. Certain calibrations have to 100 column set to 1245ma (full line pressure bleed off).