Katsushi Hashizume

Analysis and avoidance of pre-ignition in S.I. gasoline engines

Abstract In spark ignition gasoline engines, efforts to improve performance and exhaust emissions have resulted in increased compression ratios and methods of maintaining stoichiometric air-fuel ratio even at high engine load. This paper analyzes the pre-ignition phenomena under such tight conditions, and proposes a new method for avoiding pre-ignition. As a result of the analysis, it was shown that knocking occurred very frequently in the early stage of pre-ignition, which was caused by overheated spark plug or extremely hot combustion chamber deposits. It was also verified that the pre-ignition could be avoided by adding logic to the KCS (knocking control system) for screening high-frequency knocking to detect pre-ignition, and by quickly enriching the charged air fuel mixture after the detection.