So I have a 91 renix xj auto tranny and when I put it in D it痴 stays in 1st gear and sometimes will eventually shift after being almost redlined. So I unplugged the TCU and I can manually shift it from 1-2, up to 3, then into D for fourth. But with it being unplugged it loves to stall out when letting off the gas quickly. So I have replaced, the actual TCU, the TPS, the CPS, and just recently I replaced the entire transmission and transfer case and still the same problem. What in the hell am I missing? Any suggestions or help would be greatly appreciated! Thanks!

 

I'm confused about "91Renix XJ"
But, check the fuse under the glovebox for corrosion.

 

yeah, 91 is an H.O, and not a renix

since you have replaced your transmission, i would rule out the shift solenoids, but would probably go back to your TPS. check to see if it's getting the correct signal.
when my 90 renix wasn't shifting, i swapped out the TCU, replaced the fuse, even swapped out the complete transmission. did everything i thought of. nothing worked, so i just lived with it for a few years, shifting manually from 1-2, to 3 to D all the time.

so then i posted my problem up on here, someone told me to change my TPS. so i quickly ran out to my parts jeep and took the TPS from it, swapped it in, adjusted it (renix is adjustable), and wouldn't you know it... still shifting fine to this day, like 10 years later.

so not sure exactly what your issue is, but i would do as cruiser mentioned, and start there. he is the renix guru here, but like i said, since you have a 91, you are not renix. so it may be different.

 

If he's getting 1st gear with it in D, then the tcu has power. Bad TPS or damaged wiring to the TPS or transmission would be my guess, since he swapped the trans itself (and presumably the solenoids and speed sensor with it). Also verify that the throttlebody to trans cable is attached and properly adjusted.

 

I have the same problem as you except it has only really been a problem when cold. I have also replaced all the things you have exept for the transmission and tcu. However mine will shift fine the rest of the day when warm once past the first couple times.