Hi guys new to this site. I have a GN V6 in the car know and the factory tach reads about 700rpm to fast. Have crane Hi 6 box and sending a 6cyl, signal to the tach wire but it dosent jive with the FAST FXI reading at idel the laptop shows 900rpm the tach is 1500 problem remans consant though entire rpm rang at 6000 on tach FAST records 5200. Im using an adjusable shift light to controll shifts, but would like the tach to be correct also. Any help

 

it sounds like a problem with the tach, from what ive read and know the tachs on these cars are notorious for "lying" so best option if to find a car with a proper working tach and replace it...that would and should be ur best bet, also try and find a new tach from a V6 car, just to be on the safe side

 

the v8 tachs and v6 tachs read differently. since you have the original v8 tach in with the v6 motor your going to have to find a v6 tach and swap it in, and youll be set from there.