Trending DIS

Will your scope do trending?

Trending can be done by extending the time base of the signal you are viewing, in this case looking at single DIS plug firing kv. This way you see many plug firings over the time base and you will get to see any intermittent high or low firing spikes. The high spikes are from the cylinder you are viewing, the low spikes are the waste sparks on the mating cylinder.

Compressing the time base even further allows many more firings to be seen.

And even further, many more. When you are set to peak max, you will get the reading of the highest spike as above. This cylinder is lean.

See what you might see? The plug stopped firing here. Another lean one. (idle)

Cruise RPM will require opening up the time base a bit. This cylinder looks good.

Doing this will allow you to see each cylinder over time, giving you an idea of its power contribution. If kv stays high for the most part at idle and cruise rpm, you may have a lean cylinder.