Hey All! I just paid $1838 to have my 4L60E removed, rebuilt and reinstalled. It would not shift into reverse and was just redlining at WOT meaning no fun. I had it rebuilt and the reverse works, but it still isn't shifting at WOT at the 2-3 and 3-4. Even at about 60-70% throttle the trans slips and won't engage until I let off. I have a Hypertech Power Programmer and tried compensating for the different rear tire size (18" vs. 16" stock) and 3.73 gears (3.23 stock). Unfortunately I don't know much about the car as far as aftermarket add ons are concerned because it was purchased from a dealer and not from the person who did the original add ons. I know it doesn't have much because I owned a 1994 Z28 previously and the power was comparable. I know it has a Flowmaster cat back and I suspect the gears are 3.73's and not the 3.23 RPO GU5 in the glove box because I marked the tire and driveshaft and counted just under 4 revolutions on the shaft per tire rotation.
I attempted to compensate for the gears and tires with the power programmer but no matter how I raised the rev limiter and lowered shift points it did nothing. I don't know what else to try but I want to know if it could be something with the tune or if I should call the transmission place and ask WTF? He's a really reputable builder and since it seems like the problem is the same before and after it must be the tune or PCM. I have looked pretty deep into this on a couple forums but I just need to ask someone to point me in the right direction because as we all know with a Z28, there is no reason to drive it (or own it) if it won't shift at WOT. Thank you.

 

take it back to the shop and make them fix it. take any hyper tech stuff off and out of it that may be added.

 

Pretty much what I was thinking, just wanted confirmation from an experienced veteran type. I only had the hypertexh because I thought it may fix the late shift issues but it arrived after the reverse crapped out. Already took the Hypertexh off and will nicely
Consult the rebuilder as to whY he told me to "hammer down" on a car he knew didn't have any *****. 12,000 /12 month warranty on a tranny that hasn't seen 100 miles.

 

just tell him you was passing and it would not shift up.

 

Took it back to the builder, he thought it might be the TPS, but after a short ride he reconsidered. Had it a couple more days and it seemed to still shift late, but it did shift. I really think he knows what he's doing and talking about so I'm going to have the ECU flashed and see if that helps. Doesn't seem like the hypertech does anything, but it apparently had no battery so I don't think it ever stored the stock tune. Also going to try adding some extra trans fluid and see if that helps. I'm also going to order an OBD1 16 pin USB cable so I can gather more data.

 

Too much fluid will cause the fluid to aerate and make the transmission slip[

 

I read here that the 4L60E can't be overfilled because of the "puke" tube that drains the excess. Car has been parked anyway because I figure running it at high RPM's with late shifts is just going to create a much worse problem.

I'm trying to just get as much info on tuning as possible because I have an OBD2 16 pin connector which I am assuming will work since the Hypertech has the same 16 pin end. Any excess contact points won't make contact so I'm thinking they won't matter.

 

is there any truth to the puke Tube? I never heard of this before

 

95 has a obd2 connector with a obd1 pcm. only time i ever had fluid come out that tube on top was when it overheated. that was a 92 truck with a 4l60.