Tranny or overdrive sensor?
 

Hi all, any input would be great. My 90 300 z n/a started acting up over the last 2 months. It is an automatic and normally when i hit 60-65 mph, i push the overdrive button and all is well. but now she started acting goofy. the car will jump back and fourth from gears while in over drive only. I cleaned the intake ports and tuned it up, but no change. It seems to do it more while the car is still under colder conditions, but it is still random. yesterday i had been cruizin at 81mph for over 40 minutes, and suddenly it jumped up to like 2nd or 3rd gear and damn near redlined the engine!!! I braked and gases and then it was fine again for the rest of the trip. any thoughts?
thanks

when was the last time you had the tranny fluid changed?
sounds like it's time for a flush.

There could also be issues with the speed sensor and/or TPS. Is your speedo working correctly? Have you checked for ecu codes and run the a/t diagnostics?

I have not had a tranny flush since buying it, but that is a good idea. yes the speedo works fine. no, have not checked codes i need to do that.

Sounds like low fluid levels or just old ass fluid that isn't doing it's job anymore. Check the levels and get it flushed before anything else. It can only help things :D

thanks guys, i will check out all your tips!