I have a 1990 Auto tranny. The tranny will shift at 5,500 on the stock tac. But the stock tac is off. So its really only shifting at like 4800. How do i fix this??

 

bump

 

how do you know it's off?

 

for one i have an autometer tac and two we put an rpm gauge around the coil wire and it is matching what the autometer gauge is reading

 

TTT

 

come on somone on here has to have som kind of idea of what to do

 

if its not running rough at all, i'd say the stock gauge has a problem. the stock tach uses the PIP and TFI module to determine RPM, so if its not running rough, the modules are reading correctly, just the gauge is wrong. anyway, if you have an autometer, why do you care? and that also might be the problem. hooking up 2 gauges to the same signal will cause either one or both to be wrong. disconnect the autometer, i bet the stock goes back to normal.

 

I guess I don't understand what you are trying to fix. Are you tryin gto fix the stock tach because it reads wrong or are you trying to change your shift points to make it shift higher? If you have an autometer tach, why are you even worried about the stock one and why would you have two connected at the same time?

 

i have two conected because i dont know how to disconect the stock tach. and the autometer is right but its only shifting at 4,800 rpms when it should be going close to 5,500. so im guessing the stock tach is messed up and the computer thinks its at 5500 when its really only at 4800. so it is shifting early??? i want to know how to make it so it shifts at the corect rpm

 

computer has nothing to do with shift points..

you can install an shift kit and that will raise your shift points as well as firm them up alot..

you could also raise the tv pressure but that causes the pump to work harder, causing it to burn up eventaully..