TCC Shutter during Coast

[JordanSBC427]

Hello,

I am looking to try and figure out what is going on with my transmission, mainly my TCC I believe. When I bring my speed up to aprox 65 km/hr and then begin to coast down to aprox 60 km/hr the truck kinda jerks a bit, like the torque converter can't decide if it should unlock or not. I have a 427 SBC with an LS1 B computer, a 4L65E monster transmission with an 1800-2000 stall, and currently 3.73 gears in the rear end. A guy from work told me to gently tap the break and see if it goes away, he said that tapping the break should disengage the torque converter electronically....can anyone verify this? Are there any small tweaks I can do in some tuning parameters to try and rectify this issue? I believe I have attached my current tuning file. Please let me know if the attachment did not work. Any help is greatly appreciated.

Thank you guys,

Jordan.


18117

[joecar]

Post some log files, include these pids: VSS, TP, MAP, GEAR, TFT, TCCMODE, TFMPRS, TRQENG.

[JordanSBC427]

Hey Joe,

Unfortunately I won't be able to log for another month probably, as it is still winter here. I will add those pids to a log and see what i can come up with.

Thank you for the help. I will update you as soon as I can take the truck out on the road.

[joecar]

Ok, no worries, take your time.

[Highlander]

tstate pid too...

[joecar]

Yes, TSTATExx also, I forgot that one.

[Highlander]

i think 08/9 and 12 are needed...

[JordanSBC427]

Hey you guys,

I just did some logging about 20 min ago. Let me know if you are able to see anything that sticks out, or if I need to do something different while trying to log the data.

Thank you,

Jordan.

18257

18258

[Highlander]

i see it working fine... it releases by mph.. not by minimum throttle.

[JordanSBC427]

Hmmmm...well i'm not sure what the jarring could be then. It is a brand new transmission with 150 km on it. Possibly it just needs some break in time? I'm hoping its nothing mechanically wrong.

[joecar]

Do you get misfires (log the misfire counters)...?

( PCM releases TCC during misfires )

[joecar]

Transmission does not really need break in time...

transmission should never shudder... a shudder is either an internal slip, or some external event (e.g. misfire, broken mounts/u-joint/suspension/other).

[joecar]

Try this diagnostic: during coast down, tap (and immediately release) the brakes once (to disengage TCC) and then take note if problem still happens.

[JordanSBC427]

Hello Again,

just wanted to update everyone on my TCC issues. I think I have resolved the problem. It is no longer shuttering at the 60-65 km/hr in OD, and the 40-45 km-hr in 3rd. I went through all my transmission up/down shift speeds, and my TCC apply/release speeds and adjusted them. I think they were way out to lunch....I would not downshift out of OD until I was going 39 km/hr and my TCC would not release until 56 km/hr. I more or less shifted everything up a little. I should not be driving around town in OD with the TCC locked. I also disengaged the TCC lock during upshifts. I did have one slight issue when I dumped in a tune that just made changes to my TCC apply/release speeds. DTC P0757 "Shift Solenoid B stuck on" appeared. Then I came back and added my transmission shift point changes, and then disabled that TCC lock during upshifts. It seems to be shifting, and unlocking 100% better. I had zero shuttering with the TCC....so hopefully this did the trick.

If anyone could shed some light on that P0757 DTC, and perhaps why it would have appeared, that would be awesome.

Jordan.