ok i have an autometer tach that is hooked up so that all positive leads (think theres 2 cant remember) go to pos on the coil, all negatives go to the neg on the coil. my question is which do i trust, the dataloging and the stock tach read the same and the autometer reads 500 rpms lower. i was thinking that the stock tach and the dataloging were wrong since they prolly get the same signal from the ecu. i guess it doesnt really mater but i was wondering.

 

stick to stock

 

The ecu is not wrong. I'm not sure exactly how you wired up your tach but you got me lost. Isnt the tach just a 12v power and negative and a tach signal? there no reason you should be wiring the tach to the coil.

 

Here is what i got from the autometer site. There only 4 wires that should be hooked up. The red where is going to be wired up to a 12v switched power. Black wire is going to the chassis ground, make sure its a good ground also. The white wire which is the the one that lights up the tach. This should wired up to your fuse box so when you turn on your headlights, your tach lights up also. Last it the green wire which is the tach signal. This should be wired i believe to the blue? wire coming off the dizzy. Or you could just run a wire from tach signal from the ecu to the tach.

 

when i tried to hook it up like the directions said the tach didnt work at all, maybe i have a faulty tach, but when i tried it like this it worked so i left it.

 

what part didnt work? did it have power? you probably didnt have the tach signal wire hooked on the correct wire.