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Discussion Starter · #1 ·
Hey guys,
I have 1990 miata with 1995 engine (flyin miata swap kit). Timing advance to 14deg, rx7 maf. Everything worked perfectly until sometime last summer, and the winter didn't cure anything...lol.
Here is the problem: from idle to 2800-3000 rpm, the engine is stumbling, seems like it is not firing on all cylinders or something. Sounds and feel like a badly tuned traction control... After that every is good and it runs fine. Battery is new, spark plugs are nice, coil is new, sparkplug wires are 3 years old msd 8mm.

Let me know if you have any cues!

Thanks,

Ben
 

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maybe check your CAS. My blue Miata was having some trouble revving and I literally pushed down on the clip and it's been fine ever since.
 

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Discussion Starter · #5 ·
Thanks for the input. Any advantages going to higher end plug wires? Will NGK oem quality be good enough for stockish engine. I do quite a bit of autocross.
I had a pretty bad oil leak at the CAS. Changed the seal last week. The ground strap just under it is quite full of old oil. Might be worth cleaning it...

Ben
 

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If the CAS has been leaking, check if the two water temp sensors at the back of the head are soaked in oil, too. That can also lead to rough running when the engine is in closed loop mode (which it is roughly until 3k).

I'm currently using 8.5mm Magnecors on a stock engine but I'm fully expecting to have to throw these out every 30k.
 

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Discussion Starter · #7 ·
Just a quick update, it ended up being the wires...They had 50000km on them.
Thanks for the help


Ben
 

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High idle is often caused by vacuum or intake leaks letting extra air in. Would check vacuum hoses especially at connection points for good seals.
 
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