My graphs for engine rpm only, show the logger is picking up a signal from my MSD Digital 7 that is sending out a signal for every plug firing,(three or more) till about 3,000 rpm where the single spark takes over, then all is well till the rpms come back down. I talked to the design engineer at RPM, and that is the conclusion that we came to. Anybody have this issue ? Fix?

What data logger are you using Gregg?
On my LM 2 it talks about "rising edge" and "falling edge" signals.
It says if one doesn't look right try the other.

When I do the timing on my engines with digital 6 (msd) I have to bring the rpm above 3000 so the timing mark will be steady.
MSD said this is because of the multi spark below 3000 rpm.

Hope this helps, Don

RPM Performance data logger. After talking it over with the design engineer at RPM, we concluded that it is almost certainly a tach signal issue. During cranking it shows a pulse for the multiple firings, and the graph goes crazy up and down as a result. At any point below about 3,000 rpm, it shows up as a wide band like an earthquake reading on a seismometer.

Greg it sounds to me like your getting some interference from something. When i was experimenting with using megasquirt for data logging and other functions i found i was getting alot of noise and interference. After countless hours of Internet research I tired using sheilded wire on all my logging components and also isolated grounds for said components. That cleaned up most all the noise.
This is what worked for me.....Good luck