4l60E not downshifting correctly?

[RedLT4]

First off, any and all help is appreciated for the newbie.

I'm using the stock trans and converter on my s10 blazer swap and have just recently been going for short trips/ironing out issues. From a stop/or low speed, it seems to upshift just fine(though the 1-2 seems a little slow). However, when I'm running around 40-50 mph, and go WOT, the log says it's commanding 2nd, but my RPM will spike and just hit my rev limiter like it's refusing to go into 2nd?(these events happen about 14min 20s into the log and I kept doing it for a while). If I let off the throttle, it shifts back up just fine. Higher speeds seems to downshift as they should? I've looked, but do I have something out of whack in my shift speeds?

[RedLT4]

No one?

It seems I can prevent this from happening just by staying out of WOT. Say 90% on TPS, and it downshifts fine. I'm thinking the stock trans just does not like WOT downshifts.

[RDF1]

Almost sounds like 2nd gear is slipping?

Ill try and look at the log in alittle while.

[RDF1]

What was your transmission temperature?
Ive tuned a couple trucks with higher mileage transmissions and they ran great like yours was doing until several pulls and trans warmed up and would slip like that.
it appears yours was taking longer between shifts every time you made a pull?

Also your timing is very low and Spark tables look odd? high timing at the low rpms low load areas?

Edit:
Looked over the log again. Looks like your 1-2 upshifts started out at .8 seconds, then slowly went to 1.3 seconds?
Id be looking at a transmission rebuild.
But your shift timing table [ECM] 15110 could use some work. I always take them to .2 seconds.

[RedLT4]

What was your transmission temperature?
Ive tuned a couple trucks with higher mileage transmissions and they ran great like yours was doing until several pulls and trans warmed up and would slip like that.
it appears yours was taking longer between shifts every time you made a pull?

Also your timing is very low and Spark tables look odd? high timing at the low rpms low load areas?

Edit:
Looked over the log again. Looks like your 1-2 upshifts started out at .8 seconds, then slowly went to 1.3 seconds?
Id be looking at a transmission rebuild.
But your shift timing table [ECM] 15110 could use some work. I always take them to .2 seconds.

Thanks you for taking the time to help. I upped the shift timing, but it is still pretty much doing the same thing. It does seem the warmer it gets, the worse the 1-2 shift, and the more it will refuse to downshift into 2nd at WOT.

Would you even bother with trying upgrades to this trans(shift kit etc.) or just wait and do the rebuild?

[RDF1]

Honestly i wouldnt try to bandaid it. Im pretty sure the 2nd gear band is toast.
Id rebuild it before its hurt too bad to need hard parts. Then do servos and shift kit.
You need to lower the shift timing, not raise it.

[RedLT4]

Sorry, yes, that's what I meant, lowered it to .300, but the 1-2 didn't seem to care.

[RDF1]

Ah ok.
Yea you can keep driving it till 2nd is completely gone or go ahead and get it freshened up.
If you have the Torx bit to remove the bell housing, replacing the band isnt too hard of a job if you wanted to tackle it yourself.