misfire history not showing misfires

[draz53]

I'm logging misfire history cylinders 1-8, plus total misfires. When total misfires shows misfires (I get either 2 or 4 at a time), misfire history shows zero for all cylinders. So, are the misfire history pids just totally broken?

[Road]

It takes more than 2-4 misfires to trigger the history log

[draz53]

OK thanks.
Related question: the total misfires count will stay at the same number (like, 4) for some number of frames (like, say, 100), but it's a different length each time it happens. What does that mean? I assumed the software counter just timed out, but then why does it last a different length of time on each occurence?

[Road]

The only time I use or reference the history log is after a dtc has been set then I go to history to see witch cyl was misfiring. It's not uncommon for the ecm to a detect random misfire but should not be consecutive I am not for sure how many frames it takes to reset or counts to be stored as a history and is likely to be different from one operating system to another. Operating temp vs run time etc may have a affect on when or how is active. If you are seeing misfires you need to determine the conditions for setting them like at idle, under load. start up etc.