MSD coil problems

[Vettefan87]

Last year I ordered an MSD coil, cap, rotor, and wires when I did my tune up. When I put everything back in I noticed my tach only worked up until around 3000 RPM's, then it would fall to zero and pick up when it dropped below that. Well I threw in my old ACDelco coil and the tach worked fine, so I figured I ordered, or they shipped me the wrong coil. So I get online and check the part numbers, and they match! Anyone have any suggestions? I have not contacted summit yet, but I doubt that will be fun...

 

[Schrade]

Could the MSD coil be drawing power from the tach signal output?

Maybe the tach signal wire needs to be a heavier gauge for the MSD?

 

[rascal_rascal_99]

I'd probably call MSD before calling Summit.

 

[vetteboy86]

I'm running the same coil with no problems. I'm not sure how the coil would work but would cause the malfunction. I am wondering what the difference if any between 86 and 87.

 

[HuskerNation]

I have an 89 vette with the same problem. However I put the MSD coil in about 4 years ago and went through months of back and forth with MSD. They sent resistor after resistor and nothing fixed it. Finally I got a RGA authorization but never pulled it out to return it.
Problem still exists but I drive it so little I just go off sound and the feel (of power drop) if on the road course. I hope someone has an answer to this issue!

 

[vetteboy86]

I'm gonna have him throw my coil on his car.