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Old 01-13-2018, 04:17 AM   #1  
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Default Misfire issue under boost.

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
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Old 01-13-2018, 08:14 AM   #2  
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Probably spark blowout, reduce gap.
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Old 01-13-2018, 09:02 AM   #3  
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^agree. How much boost are you making?

I’m running about 13 psi, gapped to 0.030” and don’t have blowout anymore.
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Old 01-13-2018, 12:37 PM   #4  
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Originally Posted by Schroedinger View Post
^agree. How much boost are you making?

Iím running about 13 psi, gapped to 0.030Ē and donít 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.
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Old 01-13-2018, 12:42 PM   #5  
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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.
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Old 01-13-2018, 01:38 PM   #6  
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Quote:
Originally Posted by Godless Commie View Post
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).
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Old 01-22-2018, 09:39 PM   #7  
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It might also be that your coil pack is going. What year is your car?
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Old 01-22-2018, 09:44 PM   #8  
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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.
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