losing tach signal on the dyno
 

88 T2, factory coilpacks with HKS twin power.

I took my car to the dyno a few days ago and we kept losing tach up top, usually between 6500 and 7000 rpm. We put the clamp on the rear trailing wire by the coil and I told the dyno operator to set it for 4 cylinder. For the ground I just put the clamp on a bolt on the firewall near the brake master cylinder I think. I know it could've been a better ground.

Anybody have any tips?

Since you have an HKS Twin Power, try to put the clamp around the yellow wire on it's harness (IIRC).

With a Crane HI6R and my Twin Power and most of the time the same thing happens to me. Just like trying to get the TX emmissions machine to work on our cars.

The rotary is just so different that their equipment can't handle it.

so nobody has any strategies then? Clearly I am not the only one on here with an HKS twin power and FC ignition that has gotten their car dyno'd. I don't think I could get the clamp on the twin power harness the way I have it installed. It's not plug and on 2nd gen cars and I have all the wires tucked away inaccessibly.