4L80e concerns

[Kenny78]

My swapped 4l80e appears to have engine braking in OD Backstory for possible hints:

I bought and installed a 4l80e in August with an Optishift. the trans was used from a 95 wrecker truck, fresh looking rebuild. It had a very harsh 1-2 shift with anything off idle until you get fairly aggressive and then its smooth. I tuned the line pressure to what I felt was proper for general performance.

Over the last month I have become aware that it seems like the trans has engine braking in OD. Also, the 3-4 shift is geetting aggressive with light throttle only. I assumed the 1-2 was a previous shift kit and dealt with it. The 3-4 could be a tuning issue where I've got the 3-4 and tcc lock too close together. However, I wanted to include them for possible diagnosis.

Thanks

 

[Greg Ducato]

Sounds like the converter clutch is staying on, providing the engine braking, and may also be on during the 3-4 shift, contributing to the harshness.

 

[Kenny78]

Thanks for the quick reply. I looked at the "advanced" converter clutch settings(never noticed the advanced side) Basic settings are : Min MPH 35 Max tps voltage is at about 75% Advanced are: MPH to stay on at idle 42 min temp and qualification delay. The tuning graph also has a tcc firmness line that I left at Optishifts stock cal.

Is there a speed that the tcc should stay on at idle or can I skew that number
Thanks again for helping

 

[Greg Ducato]

I would never want the tcc on at speeds below 55mph or any time the throttle is close to or at idle

 

[Kenny78]

All right, thanks. I will do some tweaking over the next few days and report back.