Tach problems

[jordanfr13]

I recently installed a rallaye pac dash in my car. For the first month, the tach worked well, but then it started jumping between 6 and 8, so I soldered the connection so it would permanently be set to 8 cylinders. The jumping problem stopped, but this evening when I stopped driving, the tach went all the way to redline and stayed there. The really odd part is that when I rev the motor, the needle moves counterclockwise... I am totally clueless as to why it's doing this. Anybody have some ideas? Thanks

 

[jordanfr13]

Bump

 

[beermonkey9417]

bad tach? the ground is bad? is it hooked to the ciol or do ya have it hooked up some otherway? also if you disconnected the battery it will reset it self. so ya have to "learn it" again.

 

[mike87442]

Did you install a filter for the tach?

 

[downinit25i]

Can someone explain what exactly the tach filter does?

 

[foxtrot]

I've seen a bad connection beween the dist and tach cause the jumping behav that you describe in the post. As far as the tach being pegged at the redline, i have no clue but think that the tach could be defective... As far as a filter, Ive never filterered any supply voltage on anything that I've installed in the G...