Bouncing Tachometer

[mugen03]

So it seems like im having some tachometer issues. Yesterday when I was leaving work I went to go pick up my girlfriend and once I got to her work i noticed my tach was at 0rpms when the car was on. Firsts thoughts great wtf now, so once she got in I started driving an noticed it wasnt moving right away. I get like a block down the road then its going up and down, steady, down to 0, up and down again. once I hop on the freeway its doing the same thing till I hit about 50mph on the on ramp then it mellows out and doesnt jump anymore. This moring I took the same roads to see if I would get any jumping in the guage and nothing she was steady. Yesterday when I got home I tried to check if any wires were loose on the tranny but they were all pretty snug. so i come to the all knowing advice of ephatch. Is there a sensor that could be going bad, fuse, loose wire I didnt see?

[japarossa]

A bouncing Tach would have nothing to do with any loose wires on the transmission, it doesn't get its signal from the transmission. I have had the same kind of jumping tach (but engine not revving with the tach) problems before and it was almost always something to do with the Crank Position sensor. If your not sure where to find this sensor here is a link that shows the location of every sensor on the motor.
http://www.ephatch.com/forum/showthread.php?44017-Sensor-Location-and-part-s-for-K20-24