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Old 11-28-2007, 05:27 PM   #1
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Default Misfire

Well you all know that i'm finally MSed and in the tuning phase. I'm curious to know what would cause a misfire under load and throttle about half way? It only happens when under load in the lower rpms (2-3k) and only happens once. The AFR's are pretty rich, in the 12:1 - 13:1 range, the IAT are around 120-130 degrees, and the boost levels are around 2-4 psi.

I have a feeling its a combination of the mixture being too rich and the IAT too hot. Is this a good assumption? Still trying to tune everything, just trying to get a better understanding.
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Old 11-28-2007, 05:28 PM   #2
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what MS....and what spark mods....
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Old 11-28-2007, 05:58 PM   #3
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I have the MS 1 V3 board and i'm using the OEM ignitors and coils.

Forgot to mention that I put in the wrong settings for the dwell and ran it for a little while. The ignitor got super hot and now the tach doesn't work, but the car still runs. Maybe thats the problem? Well I have a new ignitor on the way so hopefully thats it.

Maybe you guys could take a look at my spark and fuel maps. I'll post it when i get home.
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Old 11-28-2007, 06:03 PM   #4
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you need to replace the ignitor before you get stranded somewhere.
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Old 11-28-2007, 07:01 PM   #5
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Yeah, once i fired my ignitor I bought a new one. Waiting for it to come through the mail. Too bad i didn't have all the parts for the COP setup that a lot of you are running.

What would cause a misfire under load?
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Old 11-28-2007, 07:03 PM   #6
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what spark mods?????????????????????????
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Old 11-28-2007, 07:09 PM   #7
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I'm using the spark mods that are posted in your DIY thread using the OEM ignitors and coils. I don't know of any other spark mods you're talking about??? Am I missing something?
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Old 11-28-2007, 07:16 PM   #8
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What dwell are you running and what gap are you plugs at? Those are two other possible issues besides a bad ignitor, or plugs or plugs wires.
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Old 11-28-2007, 07:19 PM   #9
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Ok, the plugs i have it at .035". The dwell i have it at whatever is posted on the DIYautotune how to mod for miata page. think it was something like 5 and 5.5, I forget, but its listed on their page.

When i took out the plugs to inspect them, they looked great. No oil or carbon deposits, looked really clean, the plugs are only about 1k miles old.
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Old 11-28-2007, 07:25 PM   #10
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Can you post a datalog with the appropriate MSQ of the car missing?
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Old 11-28-2007, 08:31 PM   #11
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He's got a fucked up ignitor.
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Old 11-28-2007, 09:43 PM   #12
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Quote:
Originally Posted by Ben View Post
He's got a fucked up ignitor.
That is exactly my thought to. Hmm my ignitor is fucked up but i am getting misfires. hmm maybe it is in my spark mods
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Old 11-28-2007, 11:39 PM   #13
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Ha ha, I hope when i get my new ignitor it fixes all this crap. Its starting to miss even more now. Looks like my ignitor is gonna die soon!!! At least I got one part for my COP system.
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Old 11-29-2007, 12:26 AM   #14
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I'll try get a datalog soon, it was fricken storming rain here!! My garage is all flooded.....Clean up then work on car.
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Old 12-01-2007, 02:28 PM   #15
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Ok, cleaned up the garage and replaced my ignitor. Still misfiring, but not as much. How do I upload files? I wanna upload my MSQ and datalog. I can't even see the misfires. Although, I noticed that when it misfires my tach bounces. Like when i'm at 2k it bounces to 3k and then down to 1k and back to where i'm at, all happens really fast. Could this be a ground issue?
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Old 12-01-2007, 02:34 PM   #16
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It sounds like the shielded wire from the ms isn't connect properly and shorting out somewhere, I had the same problem
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Old 12-01-2007, 03:03 PM   #17
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either the board needs better grounds, the tach sheild is shorted, the spark output is set to inverted, or the spark map is off.
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Old 12-01-2007, 04:34 PM   #18
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I hope its not the sheilding!! I'll go check that out today.

Braineack, would it be alright if i could see your spark map? I would like to compare it to mines.
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Old 12-01-2007, 05:56 PM   #19
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its the 9093MSPNP map advanced by 3* pretty much.
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Old 12-01-2007, 07:25 PM   #20
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oh, ok I'll try and use that as my base timing map
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