In reply to MadScientistMatt :
Ugh, I must have not recorded when it was full warmed up, trying to do too many things at once. Will try again tonight or tomorrow. Smoked up the garage with the doors open and fans blowing because of how it was running so I was running around...
So I don't know how it's possible but my timing is completely ducked. Keith, any idea how that's possible??
Re-timed and ready to rock. Purred like a kitten after I reset the timing.
In reply to accordionfolder :
Cam timing? How was it off?
People keep talking about engines jumping teeth but I've never seen it actually happen. Did you have a loose tensioner bolt?
I've had some of the VW jump but it's not too common and usually is not so good for the valves.
With how the cas is setup, it makes some sense that with the cam timing off the ignition timing, etc, got goofy.
I know some other vehicles can do it but on a Miata engine, I've not seen it actually happen. Won't hurt the valves in this case, it's non-interference.
Well, right after I posted that I realized what happened. I had shredded a super charger belt a bit before this happened from a loose wire falling into it. It had made it's way into the timing belt area in spite of me having timing belt covers - presumably from the open spot where the water neck used to be (I'll have to create a cover for it, that always did worry me). The cams stayed in time relative to one another, but were out of time with the crank - so I'm assuming that piece lodged itself in between the timing belt and the crank sprocket at one point and let it spin momentarily without the cams.
Thanks for the help everybody!
I'd make sure your tensioner is properly tensioned just to make sure. Interesting failure! Given what you describe, either you already had a different problem such as weak coils or it skipped twice.
And you might find this interesting :)
https://www.flyinmiata.com/NA/thermostat-neck-blanking-kit.html
In reply to Keith Tanner :
Ah, that'll work :)
I've followed the tensioning procedures and it seems to be the correct tension to me (and never had a problem before this - quite a bit of track time on it) - belt looked good besides some scuffs from the piece of debris I found in the lower part of the cover. I think no matter how good the tension was on the belt the mechanical disruption was going to cause a problem.
I switched back to the 1.6 style coils for now from the Toyota COP so I don't have to deal with them - they idled a bit better and felt nice (and looked nice), but I'd rather be driving than trying to figure out where the heck to put the cap inline.
Did you lock down the bolt on the tensioner or was it being held in by the spring? I've seen belts get damaged from foreign objects, but never a skip. I'm just curious. Might be worth swapping out the spring for a fresh one just in case.
In reply to Keith Tanner :
It was locked down, I'll grab a fresh spring to make triple sure, but the tension looked and felt good from my (limited) experience and it's been whooped on for a few seasons now.
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