{HEAD ~ detected value reading means} for reading {TAIL ~ said detected ion current value}, held in said hold means, immediately before starting electrical energization of said ignition coil; and 
for reading
{ HEAD ~ detected value reading means } for reading { TAIL ~ said detected ion current value } , held in said hold means , immediately before starting electrical energization of said ignition coil ; and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH