{TAIL ~ An ion current detector} detects {HEAD ~ an ion current} in at least one of the engine cylinders 
{ TAIL ~ An ion current detector } detects { HEAD ~ an ion current } in at least one of the engine cylinders
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH