Erm.. Why isn't my tach working?
 

So my tach dies when my engine gets warm. Works only when coolant is bellow 180 degrees or so and oil pressure is still high. Once its fully to operating temp, it's dead. Sits at 0RPM's (and flicks around a bit when I womp on the loud pedal).

Tach still registers in megatune and it seems to work perfectly when cold. This isn't a particularly pressing issue, but it's getting pretty annoying.

Where do I start to trouble shoot this?

You know, not 100% related, but my tach gauge stopped working yesterday. It was still registering in Megatune. I switched back to the MSQ I was using the previous day, even though I only tweaked the VE table and the current MSQ. Presto, the gauge started working again. I made the changes to the MSQ again and reloaded it into the MS. All, is well. I deleted the corrupted MSQ. I don't know what happened there, but you may want to give that a shot.