I installed my autometer tach and when I floor the car the gauge jumps up to like 8k rpm then back to the real rpm. I used the tach adapter and wired it to the ignition wire out of the engine bay fuse box. If I drive normal the tach works just fine. Its only under WOT or if in neutral and revving. Talked with autometer and they are absolutly no help. Now I know there are a bunch of different places to tap off of for the tach reff. so my question is were is the best place and does everyone else with a autometer tach have to use the tach adapter? I know the tach is good because its out of my old car.... and is the only reason I'm using it in this one.

its not one of those monster tachs is it?

Fixed!!! autometer's tech guys are idiots. For the hell of it I took off the tach adapter and wired the signal line to the tach wire coming out of the ecu and walla. Works perfect now. Autometer told me this wouldn't work and that I had to purchase a tach adapter.