Tranny Acting Weird

[Rapp16]

My transmission has been acting funny recently. Sometimes it will go into overdrive and be just fine for my ten mile drive home from work. Other times it wont go into overdrive at all and I'll be running 25k rpms going down the road at 60 mph. It also will go into overdrive occasionally and up shift for no apparent reason. The transmission has no reason to be weak or have any problems. It was rebuilt approximately 65k miles ago. Any ideas?
Thanks,
Derek

[flyineagle96]

Change fluid+filter...

[threshold]

I had a similar problem w/my '95 & it was a vacuum leak. Actually several vacuum leaks.

[wjcollier07]

Numero Uno...check fluid, color-smell-overall condition.

If it hasn't been done within the last 65k, add in Seafoam Transtune, drive for a bit through all the gears, up to 100 miles if possible...drop the pan, change the filter. Refill with a good fluid like Valvoline Maxlife Dex/Merc. Change it twice if you have the opportunity.

[Rapp16]

Thanks for the info guys. Ill check for vacuum leaks and then eventually when i have the time ill change the fluid.

[KL Mallender]

Also check for CEL codes, transmission shift logic relies mainly on speed(VSS) throttle input(TPS) and engine load(MAF), any can cause intermittant problem and may or may not blow a code, especially the TPS and MAF, good luck.

Kevin.

[crash93ssei]

The trans in my old '93 would do the same thing when I was beating on it for an extended period of time. It would heat up and not go into overdrive. As soon as it cooled down, it would go back into overdrive and all would be fine.

[repinS]

^ When we did the parts store run at the Michigan meet, mine had minor issues going into lockup in 4th gear, it would sit there and after a few seconds, would lock up abruptly. We were beating on our cars pretty hard then

I hooked up the scangauge and saw a fluid temp of 212F Too hot!