My 91 z with the 700r4 is electronic run right? I notice lately that when i first drive it, half the time it wont work for first 20 minutes or so.It seems that everytime after shifting into OD is when it starts working again??? Is there something loose in the ecm connections maybe? Thanks for any help

 

Sounds like you've got a loose connection somewhere... While the speedo is electronic, there are still gears in the transmission driving the electronic part. Its possible the gears have worn down and arent making a good mesh with each other. I saw that happen on a friend's 92 Z28.