I was completely unsure where to even put this. So I guess here is probably the best area.

I recently installed a BRP MP62 Kit on my Miata (which was a complete nightmare, story for another time) along with a fully loaded FM Link. (knock sensor, screen, etc). Between 4800 and 6000 I get a weird, harsh misfire that doesn't seem to appear on data logs. My afr will spike for a fraction of a second, barely long enough for my eyes to register it (~14ish area) right after the misfire happens. I have the NGK 7 range spark plugs bought directly from flying miata, gapped at 0.035.

Anyone have any ideas? I was thinking spark blowout. I'm out if town and won't be home until late Monday. I would like to get ideas on things to try when I get home

 

Probably spark blowout, reduce gap.

 

^agree. How much boost are you making?

I’m running about 13 psi, gapped to 0.030” and don’t have blowout anymore.

 

Thanks for the replies boys. I'm making a pretty solid 7 all the way to about 5000 where it goes up to 9 the drops back down to 7 at about 6500(ish).

Ill drop the gap to 0.025 when I get back.

 

If you are running the stock coils, then reducing the gaps will help.
Such a misfire with a COP setup indicates you'll be running on 3 cylinders very soon.
I went through a few coils that way.

 

Stock coil (sadly).

 

It might also be that your coil pack is going. What year is your car?

 

Thanks for replying gthill. I apologize I never came back and updated this.

I gapped my plugs to 0.028 (from 035) and it completely cured the issue! I appreciate the suggestions from above.