I just replaced my block I took everything out and put it back in it is the same d-series and tranny. does anyone know what this could be when the car is idling and I have it out of gear it is like the speedometer is a second tach. I don't have any after market guages it's pretty much all stock.

 

sounds like fun! find out what u did and sell a how-to on ebay


seriously tho... fugg if i know

 

Could it be a bad ground...could you have done something gay with the harness?? Recheck all your wires and grounds....like take the grounds off and clean the crap out of them and see what happens. Does your tach jump around when you drive also....it doesn't have to be much....if it "slips" around then it could very well be a ground.