GM 4l80e TCC lockup and "shift time" issue: logs, tune, and pictures for speedy diag

[kingtal0n]

Hi, thanks for looking,

I have a 5.3/4l80e, fresh swap with 150 miles. It runs and shifts very well. I just recently noticed a consistent problem however:


First picture is these screen shots I put together, taken 0.01 seconds apart. The transmission is "releasing" the TCC clutch, at the same time it suddenly shows "Shift Error 4.8s", even though no shift actually occured. Something to do with the transmission detecting a shift is causing the TCC clutch to unlock.
problema.jpg

In this picture you can see, I have shift lock enabled and the current conditions should not allow the TCC to unlock before a shift, or after it. Nevertheless, It "turns off" and unlocks, and then re-locks shortly after. It does this after a 3-4 shift, and only once, and only if the TCC was locked in 3rd prior to the 3-4 shift. and sometimes it unlocks before the 3-4 shift also (it did in this example).
FINAL.jpg


it seems that the ECU can't tell when the shift actually occurred, from 3 to 4, and this is affecting the TCC. The shift happens, but the ECU doesn't "know" or show "trans current gear:4" until seconds later. This not only causes the trans to sometimes unlock before a 3-4 shift, it also causes a brief unlock and relock after a 3-4 shift.
TIMEISSUE.jpg


Tune file and attached log that the pictures above were taken from.
6-167-17copydel4up[1].hpt

17-06-18_00-08-05[1].hpl

thank you for the support!

[monte4ever]

There seems to be a lot of 4l80e trans TC lockup problems - I'm dealing with one myself. Hope you get it figured out.

[kingtal0n]

I did a little more testing today and it definetely seems to have something to do with the shift time error, or time of last shift, being excessive for the 3-4. My 3-4 occurs in maybe .1 to .2 seconds, and it says shift time error was 5.4seconds or more, and unlocks the converter breifly. so I am going to play with the TCC slip, shift adaption, and ultimately I might just move the lockup for 3rd higher or turn it off completely to avoid this strange behavior. Also, today for the first time, the scanner locked up twice in a row. I thought that was very strange, and it happened at the same time I got a chirp shifting from 1-2 (I had given it more tps than usual).

Edit: just a following up with the scanner lock up (freezing) with more details in case other people have this happen.
for starters I am a computer tech and keep my computer parts, and the HPtuner device, cool, dry, and out of sunlight at all times. When I am done with HPtuner box, I shut the car off, shut the computer off, unplug it and put it away in the house. It never stays in the car and neither does my laptop. I have never used an inverter with the laptop, it runs solely on battery power. My operating system is windows 7 and is dedicated for tuning my car, there are no other applications on the laptop, this is to prevent conflicts and keep the computer running "free from fetter" the hard drive is mostly empty.

Now that the stage is set, the HPtuner's Scanner locked up a couple times on me recently so I want to discuss that next. The first time it happened I had put the gas pedal down (tps%) more than usual (as mentioned above). Immediately this correlation appeared accurate: the scanner would lockup when I load the engine past a certain point. The first thing I did was reduce the number of logged items on the scanner list. The scanner still locked up so I tried a different USB port. It started locking up more frequently, three, four, five times, and a couple of those were not with any unusual TPS% (it was starting to lockup at random it seemed). At this point, I tried the previous two things once more: I changed to yet another USB port and removed even more from the scanner and I was able to drive around for quite a while with no lockup issues, then i gave it some more throttle and it continued to log. I think the issue is "solved" because today I went back to the original USB port with success. The solution SEEMS to be to reduce the number of items you are logging at once. I will continue to monitor and report back.

[kingtal0n]

If I have to guess at this point, it is the converter being non-OEM that is tricking the computer into not being able to "see" the 3-4 shift. I guess the RPM drop with a stock converter is more than I have now, so it completely misses the shift. Is that sound right?

My question would be:
how can I tell the computer to stop looking for the 3-4 shift, or to be more sensitive to it? Or turn it off, etc... how can I change that stuff. I turned off adaption, which is what the whole latest shift time thing was for I thought, but its still 'watching' latest shift time and unlocks the converter once it 'sees' the 5.2seconds latest shift time error for 3-4.