A misfire detector generates a misfire detection signal indicative of {HEAD ~ occurrence} of misfiring in the at least one engine cylinder on the basis of a value of {TAIL ~ the ion current} 
A misfire detector generates a misfire detection signal indicative of { HEAD ~ occurrence } of misfiring in the at least one engine cylinder on the basis of a value of { TAIL ~ the ion current }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL