Bizarre Crank Sensor Failure at the Racetrack
 

I was at buttonwillow yesterday with my 99 miata with a m45 SC and aidz inline JR power card. The car drove perfectly fine for the first 6 sessions. On the final session 2 laps in the car begins miss firing like crazy and won't run at all. I limp it home in 2nd feathering the throttle to get into the pits.

The code reads P0339 which is a crank sensor error. Basically loss of the crank signal. Cleared the code and key cycled and no change. I let it cool off and removed the sensor and everything looks perfectly fine. Minimal debris on the sensor and no faulty wiring. I reinstalled the sensor and fired the car back up and everything was back to normal. The car drove 160 miles home without any issues but I did not get to go back out on track.

Has anyone seen anything like this before? Any idea what might have caused it? Maybe it's heat related and this will bite me in the ass again at my next track day? I'm ordering a spare crank sensor to carry with me for the next event just in case.

But I'm stumped on why the sudden sensor "hickup"...

Might this be a overheated cam sensor instead? I don't think that explains the cam code, but that seems to be the more common issue.

Slow failure? Right after hitting the curbs hard?

the results of the failure were felt immediately. No power and snap crackle pop noises like its the 4th of july. No memorable curb impacts or anything out of the normal before it happened.

Did the crank sensor move any distance wise away from the teeth?

I would guess this also. If it happens again measure it before you pull it off.

That's the only thing that I can think of that might be the cause. it's hard to imagine a bump knocking it very far out of position unless it was loose.

If it happens again I'll measure the distance. Does anyone know the spec distance from the wheel it's supposed to be at?

Business card, razor blade, credit card. Any of those 3 are the spec.