4L80E Issues

[DrX]

"New again" trans/converter are getting hot quickly even with a new 40K cooler on a 60* F day. 239 *F after 30 min of easy driving on level roads and it just keeps climbing. In the log the TCC rarely locks, but spends a lot of time in "App En" mode when it should be locked. Slip appears to increase during "App En" and decreases in "TCC OFF." Anytime the throttle backs off slightly either by the pedal or cruise control "TCC OFF" is triggered. The builder has setup the trans for full time max pressure and bumped it up to around 215 psi this time round according to my gauge. The converter was supplied by the trans builder.

The trans and converter have already been gone over by their builders as I returned them due to the heat issue, the amount of TCC slip I was logging under throttle and the "looseness" of the converter.

What is causing the heat that I am still seeing?

Why is the TCC not locking now? It was before I sent it back, but was slipping a lot at anything over 30% throttle and the converter was not stalling as it should when unlocked (e.g. 2300 RPM of slip at 5500 RPM engine speed). The spec'd stall speed was "as tight as possible" or around 2500 RPM. This is an 11" converter.

Trans issue? Converter issue? Sensor issue? Tune issue? or a combination?

[joecar]

Previous converter: was TCC locking ok and TFT was normal (around 170F)...?
Current converter: is TCC unlocking and TFT is abnormally high...?


I think there might be two problems: TCC not locking (for some reason), and converter stator problem (freewheels when it should lock).

Does vehicle acceleration (TCC would be unlocked) appear to be slowed (overly loose)...?

I'll look at your files later today.

Do the TSTATE pids indicate a reason for TCC being unlocked...?
Are he misfire pids indicating misfires...?

[DrX]

Hi Joe,

Previous converter/trans was locking/not heating up. Lost the direct clutches though.

This converter/trans combo was heating up when first installed, but was locking as described above(not holding well). At first it seemed to be locking/unlocking a lot, but that appeared to go away after I did a fresh segment swap. Didn't help with the heat or the TCC slipping over 30% throttle. After going back to the builders it doesn't seem to want to lock at all and goes in and out of App En on any throttle decrease. Less slip when in TCC OFF.

Haven't logged the TSTATE or MISFIRE PIDs this time. On the first install of this combo I didn't see any Misfires logged.

Accel seems good...the truck went sideways the few times I stabbed the throttle during this logging run. The converter seemed looser before I sent it back. The dimensions of the converter have supposedly been modified to achieve clearance with the SFI bellhousing flange where it bolts to the pump. The converter initially could not be fully engaged in the trans before hitting the bellhousing flange ..couldn't get the last click.

I will be trying another converter, if it fits, in a week or two.