That worries me even more.

I get right off the highway after 30 minutes and check it with no heat shielding at all. Still 350F.

10 minutes that thing will have cooled off by probably as much as 50%.

Well, with no heat shielding the converter itself will be cooler because all of that radiant heat will be dumped to the surroundings. Mine was after a trip on the highway as well. I'm not sure it was 10 minutes, but it was a small conversation with the wife. Could have been 5 minutes. I got distracted lol. I got my temp from the rear portion of the cat that's exposed, not the heat shielding itself.

Anyways, I'll check it again tonight, right after I stop. I live less than a quarter mile from the highway.

For what it's worth, I have seen cars that had catalytic converters that were completely broken, and they didn't affect the performance of the engine, they just completely failed emissions. Only on my old RX7 did the cat cause problems with the motor. It just didn't have any power, especially at higher RPM. The cat was clogged with ash and partially melted. Car got a lot faster after I swapped it for a pipe. Go figure.

Well from the looks of it, i've completely solved my issue.
No more low 1000-2000rpm stutter missfire when hot.


Put new ignition coils on.

One thing i noticed, my old ignition COPS are longer than the new ones. I may take one back off to snap a picture.
Does anyone have any prints or dimensions of the COPs? Specifically the socket?

Nice! Glorious resolution, comrade! :bigtu:

How long have the coils been in place? I'm curious as to if the fix "holds" and also the quality of the Rockauto coils.

I can measure the set I have, but no drawings.

New on the left, old on the right.
https://www.miataturbo.net/attachmen...ine=1424822853

Markings on the old one.
https://www.miataturbo.net/attachmen...ine=1424822853

I can't imagine they went on TOO far. Either way, the short ones are working now.
They are "ultrapower" brand. No idea how long they will last, we'll see. They were the second or third cheapest on rockauto.
The old ones were on the car when i bought it, so i'm not even positive they're the correct ones.

me too....
 

Ironically enough, I was going to write something very similar to this, but I decided to check out engine performance, and wah-la... here we are. I have an 04 msm , decided to drive it to work one day and was cruising.... all a sudden, it bogs then multiple misfire, it was so bad that it lost speed and gave a flashing CEL . You would think it wouldn't run. But it would idle.... and I say idle but barely. So I pull the car over, pop the hood, start the car then tap on the front coil a few times and bam! back in business... it did this two more times on the way to work and continued on the way home. I had already changed the plugs a week ago thinking that may be it, but wasn't... so I ordered new NGK wires, and then Ordered two new "high performance" coils . The coils came in and when I went to put them in I noticed the boots were shorter than stock, so I changed them out with the stock boots, the stocks looked fine, I cleaned them, checked the springs, and they were good.. no corrosion, or hairline fractures etc. I did this Not even trying the new short boots. I Dielectric greased everything, started it up and it ran... like ran good... at least I thought it did. So no It doesn't misfire anymore, but the rpms spike from 800 up to 2200 back and forth repeatedly when first started and When driving and accelerating under heavy load it's "ok" anything else is questionable. Certain rpms it surges especially coasting to a stop while it's still in hear, you HAVE to depress the clutch, if not it "bucks"... it does this but no CEL, just embarrassing "bucking" or "jolting" . depress the clutch and rpm will fall right under a thousand .. to "normal"... I'll also note that before when it was running as normal as it had since I've owned it, you would have to coast to a stop and have trans engaged until the engine speed was near 1200 rpm before depressing the clutch out it would die, or be close to dying (500rpm or so). I've tried cleaning the maf and the boost solenoid valve. Since then I've replaced the maf and the filter.... just very frustrated. Haven't really had the time with work, then the weather has been crazy too.... just lost my job do to restructuring so I have the "time" now.. any help is most certainly appreciated... thanks in advance!.. also.... I need a new ecu , and want a MS. anyone know how to get help on that? I've responded in the appropriate threads and pm'd Demetrius and Scott both.....I Haven't heard back... =/ again thanks for any constructive, productive input...