Infiniti I30 - transmission problem?

[1drr]

This only happens when temperature outside goes above 80 degrees. After driving for a while, maybe for 30-40 minutes, the transmission stops switching gears. It keeps staying in 1st. After I let the car cool for maybe 3 to 5 min it starts running normally. If temperature outside is below 80, the car runs without any problems.

 

[guitardc59]

When is the last time you had your transmission fluid and filter changed? It sounds like your transmission is overheating and the internal valves are sticking. Check your fluid (with the engine running) after running the engine for awhile so everything is warmed up. If it's not reddish in color, then it has most likely lost its ability to protect internal parts sufficiently and will allow the transmission to overheat.