Hallo guys !!!
For about 2 weeks, I´ve a little problem with my TH700-R4. In the 4-th gear, lockup and non-lockup changes all the time without changing the throttle-position.
In the summer I installed a 160-degree thermostat, and at the moment the outside-temperature here in germany is about 40-degree, therefore my car ( a 1985 IROC-Z ) doesn´t reach a really hot temperature. - Could this be perhaps the reason for my problem ?
I have disconnect the lockup-switch now, because it´s no fun to drive like this.
Any suggestions to cure the problem ???
Thanks

 

Uwe,
Ive had the same problem for a year or more.
Now though the convertor only locks at very low speed and not at high speed.
Ive tried a new lock up solenoid,new torque convertor and ive replaced the rubber o ring the on main shaft but i still have the same problem.I have a few more things to try when the weather warms up a bit here,so i'll let you know if i solve it
Cheers
powermite
check out my pics
https://www.thirdgen.org/rides/index...ew&rideid=4262

 

The engine temp does affect L/U as it is inhibited below a certain temp but I would expect it to still work. At this point though perhaps at least for the winter you could try the 180 thermostat and see if the problem goes away. Also make sure there are no air pockets.

Losing L/U above a certain throttle position sounds like either the clutch isn't holding or perhaps there is a TPS problem causing it to unlock.