Misfire Analysis with Time Interval Analyzer

Engine misfire is a critical parameter in emission control. Very lean mixtures may cause misfires and a sharp increase in unburned HC ( hydrocarbon). Correct mapping of the ECU requires accurate knowledge of misfire timing. There are several traditional, but complicated methods of misfire detection. The period of crank pulse will vary at misfire. Therefore, using the Yokogawa Model 320 Time Interval Analyzer, the crank pulse period can be measured and detection of the longer pulses of an engine misfire situation is easily possible.

Solutions
The Yokogawa Model TA320 provides the following solution for this application :

1. Continuous Measurement
The TA320 can continuously measure the period, pulse width and time interval of the signal at a maximum rate of 14 MSPS with a maximum time resolution of 100 pico-seconds. Thus, rare misfires are easily detected.
2. Time Stamp Mode
The TA320 has a Time Stamp Mode as its sampling method. In this mode, measurement values and its measurement time are each measured, enabling the variation of the measurement results with time to be analyzed using a time variation display. This is an excellent method of detecting misfire timing.

The figure at the left is an example of the misfire detection.