I recently bought a 93 z28 with a rebuilt 4l60e. The pervious owner had some stuff done to the tranny, hypertech stage 2 chip
alum ls1 driveshaft w/ new brut force u joints
Vigi 9.5" 2600 stall, shift kit, art car input shaft re-inforcer, alto kevlar band, upgraded servo and pump. After I got the car I noticed that at times while the shifter was on overdrive and I gave it 3/4 throttle +, the engine would rev as if in nuetral, if I let off the throttle a little, it would go back into 3rd like normal (kickdown). It did this for a week or two until one day while on the freeway, gave it 3/4 throttle and it did the neutral thing, but when I let off, it shifted to 3rd and wouldnt go back into 4th. Now, if I manually shift through the gears 1-3 the car shifts fine, but wont go into 4th. If I leave it in overdrive, it just sits there and revs. If I try to start off in 3rd or 2nd there is a hesitaion, but it will go. Would this be caused by maybe a servo, or could it be the chip doing this if it is going bad. I really dont know, this is the first auto car that I have owned. Thank for any help

btw, the fluid was fine when this happened, but over the past week, I have driven the car 2-3 times to the convience store and the fluid seems to be slightly burnt. Also checked the detent/TV (not sure of the name) cable.

 

*cough* rebuild *cough*

 

thats what i was thinking, just hoping it might be something samll

 

That's the exact thing that happened to my tranny. I toasted the 3-4 upshift clutch, amongst many other things, like the cracked piston, shot servo's, contamanated(?) TC. Sorry man, it was an expensive fix. If your not modded, look for rebuild units.

 

fwiw, your car isnt a 4l60e, its a 4l60 (i.e. no electronics except for lock up) but they cost as much to build, and you need a rebuild. sorry, prorac1

 

oh well, thanks for the help guys.