We have developed the New Ion Current Combustion Control System (ICCS) which can control individual cylinder air fuel ratio and ignition timing. And also we could get the significant improvements of performance by adapting this system to our small displacement 3-cylinder engine. The characteristics of this system are as follows. 1.To simplify the system architecture, the ignition plug are used for detecting the Ion current, while part of the accumulated energy from the ignition coil is used as the bias power supply. 2.To improve the performance for detecting the ion current, the center electrode of the ignition plug are used for the positive pole of the bias power. 3.To overcome the lack of repeatability of the ion current magnitude, the following new controlled variables are introduced for the combustion control. For the air fuel ratio control, the variation rate of the ion current duration (ICOD) are used. For knocking control, the variation rate of the magnitude of ion current filtered through the frequency band corresponding to knocking are used.