Black LS1 T/A

Tranny is a built 4L60E (3400 stall). Driving around, it shifts fine, every gear crisp and clean. But, if I lean into the accelerator at WOT (just for a few seconds, because I haven't had it tuned yet, or give it about 3/4 Throttle, where it is pulling strong (but only has a couple pounds of boost) ... once I get out of it, the engine revs, then when I slow to where it is moving forward in 1st, it won't change unless I get up to about 3500 RPM. I get another shift out of it to the next gear doing the same.

Once I shut it down and come back 15 minutes so later, it's fine again ... strong, solid shifts at low to medium acceleration. If I park or shut it off and crank back up immediately, that does not reset the condition as waiting 15 minutes or longer.

What do you think is going on? Could TPS be going bad? What are symptoms of that? Car's been out of commission for years and I can't find my damn EFILive Tuner. My wife moves crap around and I can't find it. Gotta search some more for that in the storage room. All I have is a basic OBDII interface Blue-toothed to my cell phone via Torque app. So, I can’t see gears I'm in, though I can check PIDS like temps, throttle angle, codes and stuff I already see on the gauges.

This happens whether engine is just warm or hot.

Black LS1 T/A

Someone suggested it is seeing Positive Crankcase pressure and going into a kind of limp mode.
But the shop that put things back together on it calls BS: "You have an LS3 valley cover with a check valve and vacuum connected to it."

I called the Transmission shop (in California) that built the transmission.
(I got the tranny from an LS1Tech member back when I bought the Corvette block off the classifieds here. I want to think the guy did not sell me a tranny with known issues. He appears to have a good selling record.)
Transmission shop guy said he thought it might be a heat issue where the transmission may be defaulting to the "hot" shift tables and may need adjusting. Unless the shop I took it to for hooking up remaining items and get me inspected changed something prior to final tune, my last tune has the shift points matched for hot and cold, I'm pretty sure.

I have a trans cooler on it.

Black LS1 T/A

Though (neither admits it and I would have no problem with someone forgetting something as long is it is handled), someone left the cable off the Knock detectors. I wonder, since I've read this can send a vehicle into low-octane tables, if it could also affect shift points; I still don't get the precise correlation.

When I get home, I will get them connected back up, though. I have purchased another EFI Live Scan and Tune, so that should be here tomorrow.

If you don't want to spend boatloads of money, some things you have to do your self, I guess. I wish 4L60E was like rebuilding a TH350 (I used to rebuild mine in my '82 TA whenever necessary). It looks like it takes 4 or 5 special tools just to disassemble, inspect and reassemble the 4L60E. :-(

mrvedit

There is no "Positive Crankcase pressure" sensor (nor Muffler bearings) in your car; so yes that is BS.
Why not just be patient, hook up your EFI scanner and check the trans temp and make sure the TPS goes from 0% to near 100%.
It does sound like the PCM is reading more throttle position than there is.
Also check that your MAF signal is right.

Black LS1 T/A

Good advice ...I will do that