So are you using smt6 as fwddsm says? That's a piggy back too.
What sprinkler system?

EDIT:

Ok I went to yout site and you have smt6 and mega. Smt6..aka Power paq, 'piggy back'. One fatal flaw, cannot retard or advance timing.
Pulling fuel to increase timing doesnt count.


Now MS, thats a nice piece, because it over comes the flaw above + open source.

I still rather adirect PCM flash over the MS. Direct control, no wiring needed. No other 'system' to troubleshoot when things go wrong.

Rememer we got on this topic because of my comment about hacks/piggy back. I still stand by that. I dont deny that the can make power.