I had a problem with a RCEXL Opto Engine Kill setup that matches what you're saying... turns out that it did something to the ignition too (replaced new from Tower Hobbies).. I don't use them anymore... and love my DLE's... BTW... I'm machining a copy of the auto-electric starter available for DLE55's for the DLE20... I'll have a post soon on that project.

I have a couple planes with auto start (TF GS FW190 and a bash P51 ARF) and they are the coolest thing since 2.4GHz