I have a shifting problem with a Turbo 400 Trans. The problem is when the truck is cold the gears will hold; 1st to 2nd will shift at 25mph, 2nd to 3rd will shift at 70 mph. After the truck warms up (10 – 15 minutes of driving) it will shift fine. 3rd gear will kick in at 45mph
The specs are Chevy ¾ Ton 4x4 with a 1984 style 350 engine with a 1989 T.B.I. unit. Edelbrock Cam & Intake Manifold. Hedmen Headers, the Trans is a Turbo 400 which was rebuilt 500 miles ago and the issue did not go away. I have brought it back to the shop where the trans was done but they say it is a vacuum issue so they will not touch it..
I have changed the MAP Sensor and the O2 Sensor and have gained some more horsepower but it is still shifting wrong when cold.
Thanks in advance for all your help.