navalhawkeye

So, I'm on my second cam sensor this season (3 autocross events), and probably the 5th one in the past two years. I know these things are supposed to be fairly common wear/failure items, but I seem to be going through them a lot more than anyone else.

Setup
Car: 1996
Engine: 2001 vvt
ECU: Reverant MS3 Basic

All sensors have been from Mazdaspeed, with the exception of the original one which came with the 12k mile junkyard engine. The OEM one lasted well over a year of autocross (2014 season, into start of 2015 season). I know the new Mazdaspeed ones are supposed to be junk, but this seems a bit ridiculous to be on a 3 event cycle with them.

hector

Pardon my ignorance but I have never heard of issues with cam sensors and high replacement rates. In any event, high failure rates of electronic components suggest an underlying problem. And I find it even more odd since the cam sensor doesn't do much of anything. It's just a coil, no?

I would check your wiring for bad ground. Or for continuity to another wire. And since it goes on the valve cover and there is such a thing as manufacturing tolerances, maybe it's sitting too close or too far from the cam trigger. How you would check that I don't know.

My VVT swapped car hasn't needed a cam sensor ever and it's seen quite a few autox's and it gets driven about 4k miles a year. It's on the sensor that came with the junkyard engine and that thing probably had more than 100k miles.

Chiburbian

iTrader: (1)

https://www.miataturbo.net/ecus-tuni...failure-74009/

Well, it appears it is a heat related issue at least in general. I can't comment on NH's issue, but it is something people are keeping an eye on.

hector

That thread is definitely a good read and the OP should be in it instead of adding to this thread. It seems like his problems are quite a bit more severe. From reading through most people have misfire issues or intermittent sync losses that go away once the sensor cools down. He seems to have damaged sensors that won't even start the car.

Also from reading through it, it seems a rather peculiar problem that is affecting a certain few. FWIW, I drove my car to the Dixie Tour in '15 which is an 800 mile round trip. The trip back was non-stop and at 70-80 on the hiway. This was on the inferior DIYPNP. Never had any issues. I'm now on an MS3Pro module built ecu and same thing, no issues. And I live in sub-tropical weather. It seems like I should be knocking on wood or something.

navalhawkeye

So, I switched to a 36-2 trigger wheel and the issues seem to have gone away.

PatCleary

Big problem for the SM guys. I think it ended up being a connector issue.
Cam Sensor Issues / Fix - Spec Miata Rules & Competition - Mazda Racers

MX5RACER

The reason the NB cam sensors fail all the time is because they have this symbol on them:

hector

Haha, I recently had a cam sensor act up on me just as others have described. I knew I should have knocked on wood.

However, it still wasn't the same experience as it was for the OP. I was running with a co-driver in 90* heat with runs only about 5 minutes apart and he was not raising the hood or running the engine after he got back to grid. At the end of my 4th run, the engine started dying. Cooled down the senor with some water and time and it started back up fine. Kept hood up and engine running entire time after and kept running water over the cam sensor area. No issues. I will be keeping a replacement sensor since its a quick enough swap, even between autox runs.

Still much different experience than OP though. Don't know why he was not getting the sensor to work even after it cooled down.

navalhawkeye

To expand more...I am currently using a cam sensor that had "failed" previously, but now works fine with the 36-2. But, this same sensor will not work with the OEM crank trigger wheel, as is the case with all the other sensors I have that have "failed." I'm not remotely smart enough to come up with any reasons as to why that's the case.

Can't remember if I mentioned it or not, but the intake cam is new this year straight from Mazda, with the cam ring welded in place.

I did experiment with the Evo sensor, but as others have found it doesn't natively allow VVT to work. It doesn't see the double tooth side of the cam ring, and only picks up one. I wanted to see if the Mazda sensors were going to give me further issues before making modifications to get that to work.