Alright lets see if you all can figure THIS problem out.
I own a 94 sunbird LE with the 2.0 DIS engine, and it is a 5 speed but that does not change much. ANYWAYS, I bought a powerfist tach from princess auto and installed it, everything worked great until I payed close attention to it, well from what I know I am pretty sure my engine does not Idle at 450 RPM and I am SURE my shift points while pushing the engine are not at 2500 RPM. I DO have the cylinder selector in the 4 cyl position. NOW I took back that tach and tried another one, that one was not DIS compatable *thank god the guys from princess let me try a few.* I tried a couple more and they red the same. So I took off to LORDCO *dadada* and bought a Hastings tach *good stuff* Installed it, and Low and behold, SAME PROBLEM.
Now how I have it installed.
I got red wire to 12 volt lead in stereo, ground is to metal plate in car, light is also to radio, and the green tach whire is spliced into the white tach out signal wire off of my ECM. I made sure this was teh right wire cause no other wire puts out the same signal as that one.
I used a multi meter on the white wire grounded to metal plate, well this part confuses me, the display shows the RIGHT RPM! Fancy that. Why on earth would my tach not show the right RPM but the multi meter show the right one.
If anyone has any ideas please lemme know.