Hello everyone.
I have owned my 1994 infiniti j30 for about a year now. When I bought it, it had electrical transmission problems which I found out was being caused by chewed wires on the driver's side. I mended up the wires and the car ran great for a while. Recently, the transmission shifts back into third gear out of fourth gear at cruising speeds of 50-75. Also, it sometimes shifts hard when upshifting. I have already replaced the throttle position sensor, neutral safety switch trying to solve the first problem. I monthly check my fluid and it is at the perfect level. Does it mean that the bands need adjusting? Or what? I really appreciate any ideas. Thanks!

Nothing to do with the bands, you are having more electrical issues.

We experienced something similar but only in the rain, everything checked out, no codes etc. at a loss I changed the neutral safety switch and trans computer with known good used spares and have had no issues since. In hindsight I really think it was the neutral switch.

Okay. I will have to check out that neutral safety switch again. Hopefully that's the problem. I hope I dont have to go through the trouble of replacing the trans computer. I would much rather just have to replace the switch. Thanks for the info.

Even though I suspect the switch the trans computer is actually easier to change.

My upshift from 1 to 2 is not smooth, unless one accelerates very gently. IIUC this is a universal problem.

Just came across this thread, my transmission shifts hard from 1-2 also then 2-3 seems like a lazy shift. I checked the fluid also and its good color and doesn't smell burnt. I don't have a CEL on but its been slightly chugging alittle just recently at low speeds, the J30's got 163k on it. Any INFO would be helpful I'm still trying to figure out this car and her quirks. Has anyone had this issue with their transmission.

Do you have the FSM?
Lots of service info there!
One cause of your problem might be a misaligned throttle positioning sensor.