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Old 12-20-2013, 12:39 AM   #1
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I have a 92 miata with a 1.8 turbo, megasquirt 3 by brain. I have pretty much everything set the way he made it. When I am getting on it and I hit 5000 rpms and under boost it acts like its hitting the rev limiter, if i cruise up easy to it I can pass 5k no prob. I am thinking I am having spark blowout but I am not sure, I am gapped to about .033 right now on stock coils. When it happens I go super lean, at least according to my wideband gauge. I made a log, this is the first time I have used the data logger. Any input would be great. Thanks in advance.
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File Type: csv 2013-12-19_23.08.56.csv (462.2 KB, 45 views)
File Type: msq CurrentTune.msq (157.7 KB, 72 views)
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Old 12-20-2013, 01:43 AM   #2
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Originally Posted by themetalman View Post
I have a 92 miata with a 1.8 turbo, megasquirt 3 by brain. I have pretty much everything set the way he made it. When I am getting on it and I hit 5000 rpms and under boost it acts like its hitting the rev limiter, if i cruise up easy to it I can pass 5k no prob. I am thinking I am having spark blowout but I am not sure, I am gapped to about .033 right now on stock coils. When it happens I go super lean, at least according to my wideband gauge. I made a log, this is the first time I have used the data logger. Any input would be great. Thanks in advance.
That is a composite log. You need a data log. It is up top on the menu, under Data log>Start or CTRL+L

Anyway, sounds like overboost protection. How much boost are you running? Your overboost is set to 211kpa in your tune
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Old 12-20-2013, 08:25 AM   #3
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I am running 12 pounds of boost, my math tells me 211 kpa is 30 psi, none the less I will turn it off and see if that changes anything.
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Old 12-20-2013, 10:04 AM   #4
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Turned off boost control, did the same thing. This time I got a log. I don't know whats going on. I still think its spark blow out.
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Old 12-20-2013, 10:44 AM   #5
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I had something similar happen because my vtcs butterflies stayed closed. I unplugged the solenoid at the backk of the intake manifold and it was all better.
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Old 12-20-2013, 11:14 AM   #6
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Spark problems.

If it started happening suddenly, pull the spark plug boots to check for fluid in the spark plug wells.

If no fluid, gap down from 33 thousandths to 25 thousandths.

If it started happening gradually, replace the spark plug wires.

You are going "super lean" because the oxygen is not getting used in the combustion process, so the sensor sees a full breath of oxygen.
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Old 12-20-2013, 01:57 PM   #7
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Ryan, my motor is out of a 94, so no butterflies in the the intake. I am going with fooger, I had the same problem on my Jetta witha 1.8t. I will report back with results.
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Old 12-20-2013, 02:21 PM   #8
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That's blowout. Going lean is another sure indication. If you gap down to 25 it will improve but you will eventually need stronger coils to boost more.
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Old 12-20-2013, 11:11 PM   #9
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Might just need stronger coils, I gapped down to .025 and it's still doing the same exact thing. I just traded my porsche for another turbo miata that runs pretty good, I will swap around coils and see if that fixes it.
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Old 12-28-2013, 10:42 PM   #10
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Well I swapped coils and wires from a known good car, still get the exact same thing. Sure could use Brains help.
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Old 08-28-2014, 06:32 PM   #11
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Was there ever a resolution on the problem?
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Old 08-28-2014, 10:05 PM   #12
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No I haven't fixed it, I took the car apart for paint, it's going back together now, while I had it apart I installed a new begi exhaust manifold and upgraded to Toyota cops. I will see how she runs after I finish and see how it goes.
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Old 08-29-2014, 03:27 AM   #13
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Okay I was just wondering having a similar issue
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