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So the other day I take my car out for a ride and noticed that my Autometer tach is off from my factory tach by roughly 500rpm. My factory tach now is the accurate one where i thought the autometer one would be more accurate... When im idling at about 800rpm, the autometer tach reads about 1300-1400rpm. they both climb in rpms at the same rate, they are just off. WHY???

factory tachs are always off, but if i remember right when your car was put together your tach was fucked up it never was accurate

Tim that is false. Ive been driving my car everyday since it was put together and both of the tachs have always been in sync with eachother. This just started the other day and i noticed it right away.

it did have a bad ground before as it only worked with the lights off for some reason, but it was always in sync with the factory tach. once the ground was tightened up it worked fine....

Timbo8650 wrote:

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it did have a bad ground before as it only worked with the lights off for some reason, but it was always in sync with the factory tach. once the ground was tightened up it worked fine....

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I agree, the ground is first place I would check.

for some reason when i start my car my tach goes to 1.1million rpms and it stays there until i hit mach 5 then it comes back down.