Running rich afr 11.8 results in jerky engine performance - Miata Turbo Forum - Boost cars, acquire cats.

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Old 11-26-2014, 07:16 AM   #1
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Default Running rich afr 11.8 results in jerky engine performance

When in boost, I have my AFR running on 11.8, starting from 100kPa.

But when I'm running 11.8 the engine is running jerky / hassitant /shocks. When setting leaner (11.8 to 12.0) the problem stops and the engine is running smooth.

I do have a wideband which is (last week) calibrated.

Why can't I run richer than 12.0 on my 2002 1.9 NBFL engine?
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Old 11-27-2014, 10:59 PM   #2
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What is your spark plug gap?
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Old 11-28-2014, 04:14 AM   #3
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1.1 mm
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Old 11-28-2014, 09:20 AM   #4
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Should be at .71mm for turbo. The increased air/fuel density makes it more difficult for the spark to jump the gap with our weak stock coils so it needs to be gapped down. This may or may not solve your problem but it will solve others you would have eventually. It makes a big difference in spark blow-out.
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Old 12-02-2014, 03:29 AM   #5
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Sparkplugs "regapped", this weekend trackday, I will let now if it worked.
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Old 12-02-2014, 07:59 AM   #6
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11.8:1 at 100kPa is REALLY rich.
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Old 12-06-2014, 08:00 AM   #7
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Yes things are a bit better but I changed the afr to 13 for the low rpms. It seems that at higher revs, the issue is not present.

Can I upgrade the coils to better ones? Is there a brand/type that is plug and play to my ms3?
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Old 12-06-2014, 12:45 PM   #8
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Old 02-17-2015, 10:39 AM   #9
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The Toyota COP's seems to do the job

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Old 02-17-2015, 10:41 AM   #10
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cool story bro
did you figure out a mounting solution for toyota cops on a vvt engine or are you running gm or other coils?
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Old 02-17-2015, 01:03 PM   #11
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Toyota cops from a yaris, 16 euro on ebay. I will post some pics tomorrow.
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Old 02-17-2015, 02:24 PM   #12
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We've found LS coils to be a bit hotter than Toyota pencil coils, and ones like our IGN-1As are hotter still.
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Old 02-17-2015, 05:22 PM   #13
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Quote:
Originally Posted by Braineack View Post
11.8:1 at 100kPa is REALLY rich.
It won't cause jerky engine performance. In fact, I know from personal experience that you can run N/A motors well under 10:1 and they will continue to run smoothly at WOT.
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