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Mysterious mods misfire (MMM)

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Old 07-01-2024, 08:10 PM
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Mysterious mods misfire (MMM)

I’ve just got a Rx8 and it has developed a misfire over the last couple of days mostly at high rpm but after piddled around with the coil to plug wire connections it is now idling poorly. It looks like an aftermarket coil and spark wire system, anybody know what the aftermarket parts are? Also the connection between the coils and the spark wires is corroded and is slightly green, would that be enough of a problem to cause a noticeable difference even with that high voltage?


Old 07-01-2024, 08:36 PM
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High rpm misfire usually merits a check of the cat.
I don't know what brand of ignition kit that is but the coils are D585, which is a very common upgrade. Red ones like that are available on Amazon and should probably go straight in the garbage, but there may be legit red ones from reputable manufacturers.
Old 07-01-2024, 08:40 PM
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It also looks like someone took a sledge to your engine hanger to get the coils and adapter harness to fit, and you have wires sitting up against a sharp metal edge. Matter of time before it rubs through the insulation.


Proper D585 upgrades like BHR tell you in the instructions to remove the engine hanger.
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Old 07-01-2024, 08:59 PM
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Originally Posted by Loki
It also looks like someone took a sledge to your engine hanger to get the coils and adapter harness to fit, and you have wires sitting up against a sharp metal edge. Matter of time before it rubs through the insulation.


Proper D585 upgrades like BHR tell you in the instructions to remove the engine hanger.

what do I look for in the cat?
Old 07-01-2024, 09:45 PM
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It needs to not be clogged or broken up inside.
Old 07-01-2024, 10:33 PM
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Originally Posted by Loki
It also looks like someone took a sledge to your engine hanger to get the coils and adapter harness to fit, and you have wires sitting up against a sharp metal edge. Matter of time before it rubs through the insulation.


Proper D585 upgrades like BHR tell you in the instructions to remove the engine hanger.
Truth.
I didn't see that in the instructions, or that was a later addition.

I had to have mine towed home from work on a freezing windy day after mine shorted out and kept popping the ignition fuse.

Personally, I think that looks like a half fast kit.
I'd junk it and get lifetime OEM coils from Advance.
Save your receipt and you'll never have to buy another coil again.

I assume you're aware the wire is disconnected?


Old 07-02-2024, 06:05 AM
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I agree with the above two posts in that I would also get rid of that coil setup. I would either go back to the original coils and bracket or just spend the money and get a nice kit from Black Halo Racing. I think it would be a good starting point if your misfire is in fact ignition related. It might be worth replacing the coils and checking live data to confirm it's an ignition miss. I would also replace the spark plug wired and spark plugs at the same time you replace the coils. These engines are very sensitive to good ignition components.
Old 07-02-2024, 07:09 AM
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Originally Posted by mazdaverx7
I agree with the above two posts in that I would also get rid of that coil setup. I would either go back to the original coils and bracket or just spend the money and get a nice kit from Black Halo Racing. I think it would be a good starting point if your misfire is in fact ignition related. It might be worth replacing the coils and checking live data to confirm it's an ignition miss. I would also replace the spark plug wired and spark plugs at the same time you replace the coils. These engines are very sensitive to good ignition components.


Based on the advice given here, and the ramshackle arrangement of the coil currently I will probably revert back to stock. Here are some pictures of the connections from the coils to spark plug wires. Do y’all think that there’s kind of corrosion would be a problem with that high voltage? Could that have caused a problem?


thank y’all for the help!




Old 07-02-2024, 07:33 AM
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It's definitely time to change them.
A lot of of us do or did coils, plugs and wires all at once every 35k miles are so.

Be sure you don't cross your wires, tag them with masking tape 1 at a time.
If you don't see a wire loom to keep your wires separated, get one.
Be sure your wires aren't rubbing on the engine.




Old 07-02-2024, 08:43 AM
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Doesn't look like that connection had electricity going through it.
Old 07-02-2024, 08:50 AM
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I was told the spark plugs were replaced very recently, I plan to replace only coils and plugs. Someone told me that corrosion on the high voltage side of the coil wouldn’t make a difference
Old 07-02-2024, 09:05 AM
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Well, if you were told they were changed, nevermind.


Old 07-02-2024, 10:12 AM
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Originally Posted by BigCajun
Well, if you were told they were changed, nevermind.

I assume you are being sarcastic, as much as I’d love to change them, I am running a bit low on cash.
Old 07-02-2024, 10:26 AM
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As of now, I have pulled the old coils and put original style ones in their place. The nuts are gone, so I’m going to have to find some of those. Now that I’ve got some better pictures of the coils, what do you think?




Also, if y’all have any input on whether it is a problem that there is corrosion on the connections between the coil and the spark plug wires, somebody told me that it doesn’t really matter if it’s high voltage like that.
Old 07-02-2024, 10:34 AM
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CarHole? Sounds like a winning brand. :/
I'm not sure how corrosion can "not matter". Anything that makes it more difficult for your coil to discharge slowly destroys the coil. If it arcs, the arcs destroy the connector and the coil. You can probably clean up the connector in the wire, but then again if you're not using D585 coils, you don't need those wires.
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