Hi guys,

I have a 98 ES300 with 250k miles on it. About a week ago, it started having a wierd transmission problem where it would stay in 1st gear and take upwards of 20 seconds to shift into second, while maintaining 4k+ RPMs. I replaced the output speed sensor and the problem got better but still doesn't like to shift below 3.5k unless I manually take my foot off, which then it will. Shifts are still smooth and quick when it decides to change gears, 2/3 and 3/4 seem fine, though 4/3 downshift is somewhat slow. I checked with O/D off and it kicked up so I'm 99% sure O/D is functional. No transmission related codes, though has a P0171 lean code. I found some unhooked vacuum lines which I reinstalled in their correct spot, though its still whining. Seems that its still a cracked vacuum line because the live data shows fuel being added and the vacuum lines being reattached made the sound much louder. No transmission specific codes were found, tranny fluid is brown but not black, doesn't smell burnt. Previous history was car was owned by my grandpa, so maintainance was not great outside of the absolute necessities, but not driven hard for any of its life. Any idea why it is shifting late?

 

First thought is, ATF should never be brown it needs to be red. By the time it turns brown it has long passed offering proper protection. Problem is if the fluid has long been neglected replacing it means you also drain out the friction material that used to be on the clutch packs, and the transmission starts slipping.

Your lean code will cause all kinds of problems you need to get rid of that first.