4L80E shifting issue

[TransAm-Z]

Problem is when I spin the tires off the line and get out of the gas it shifts to 2nd, then when I get back into the gas it kicks down to 1st, but then the trans never gets a command to shift back to second. The log shows that 2nd gear was not commanded to shift until after I got out of the gas bouncing rev limiter.

On a good run with no spinning, the trans is shifting fine.

Can anyone see what is going on with this setup? I am stumped....

Thanks.

[TransAm-Z]

The shifting problem happened again this morning. Car downshifted from 3rd to 2nd like it was supposed to, but never commanded a shift out of second until I got out of the gas. I did not notice this issue until I put the new gearset in the trans (2.10 first 1.40 second)

From what I understand after a kickdown shift, the computer should use (2) tables to command a shift. (SHIFT at RPM D0940-D0971) (SHIFT at VSS, D0910-D0965). Both conditions are meet, but the log shows the PCM never commands the shift.

What am I missing?

[joecar]

I'm looking thru your files...

so it also missed the 2->3 upshift...? Do you have a log of this also...?

[TransAm-Z]

Thanks Joecar! This stuff is driving me nuts!

Attached is the log of the issue this morning. You can see in the screenshot the car shifted from 4th-3rd-2nd. Then held second until it bounced off the REV limiter, then I got out of the gas and it shifted.

I hope this is just something I am missing in the tune.

[joecar]

I'm still looking at your files, but in the meantime try this: reduce the WOT RPM shifts down to 5000 rpm and do a test drive.

[TransAm-Z]

Here is another log of the car at the track a couple weeks ago. It had a personal best 60 ft of 1.35 with minor tire spin.

If you look at this log, the shifts are also being commanded weird. The motor never hit the rev limiter on this run, however the 1st gear shift ran past 6000 rpm and 47mph which is were they should be commanded to shift. For 2nd gear the motor never reached 6700 rpm, (Unless you count the time it took to pull the motor down from the 2nd gear shift) but it shifted at the correct 104 mph.

[HOWQUICK]

stop it shifting back to first in the kickdown (2-1 down shift)...they get lost in their modelling. Been through the same thing myself and only cure was to not allow it to kick down to first until like a low speed...

Let me know how you go.