The experiment was carried out during no-load condition for analysis of the relativity between MAP, hot film, oxygen, the secondary ignition and injector waveform. The experimental methods using oscilloscope were employed to measure waveform. The relativity between several waveform and the secondary waveform coming from ignition coil were measured in case of three decrepit vehicles. From these results, a summary of the important results are as follows. 1. Through fast acceleration experiments, the response time values of hot film sensor and oxygen sensor was faster than the those of the MAP sensor and oxygen sensor. 2. The values of spark line duration time was largest A, C, B type in the order named. And discharge energy of the secondary ignition waveform was largest A, B, C type 3. The value of effective discharge energy is to be nearly proportional to the spark line duration time. 4. The value of effective discharge energy directly increases as revolutions per minute increase, and the value of spark line duration time decreases as revolutions per minute increase.