NB1 shut off while cruising in traffic, cranked fine but no start.
 

My 1999 NB1 (unknown maintenance history aside from what I have changed so far: spark plugs, new radiator and hoses, air filter, ignition coils) randomly shut off last Wednesday while I was cruising in traffic on my way home from the shop (brand new soft top installed). I was lucky enough to coast off the freeway and into a parking lot, all while trying to crank the car over but to no success.

To add to the weirdness, when I went to diagnose any engine codes that came up on Sunday, the miata started up just fine with 0 issues and idled great (did this three times). I dove through forums and it sounded like it could've been a clogged fuel filter or even a bad fuel pump. Others were saying there's a ground that isn't grounding. I bought a new DW200 as I plan to swap the pump anyways for e85 down the line and a new filter as well but I wanted to ask if there is anything else I should check to ensure this wouldn't happen again as I sometimes drive the car on my 3hr daily commute.

I tried looking up anyone else with a similar problem where their car started a few days later like there wasn't a problem but struggled to find a similar experience so I wanted to post this here to see if anyone has had this experience or knows what I should be checking first instead of fuel. I am the 10th owner of this car and is was salvaged before earning a rebuilt title around owner 6. I don't know any maintenance records about this car so I've been taking the build slow as I replace a lot of parts in prep for a build. As mentioned above, I changed out some easy maintenance items.

If there is a forum I did miss where someone had this similar issue, please link it below! I searched for a few days before typing this up. All help is appreciated!

I should mention that the car starts and runs now, unsure if that was clear in the post! Haven't driven it since Sunday as work has been really busy.

Search with this: < site:miataturbo.net "cam sensor" > using Google.

see the hit from 7/20/2013

DNM

I read through a good chunk but the difference between my car and the cars described in the thread is that I don't have a DIYPNP. I'm curious about heat soaking the sensor and wonder if that's what I'm experiencing. I'll look into this further and consider a new sensor if this seems to be the likely cause, I appreciate it DNMakinson!

Main Relay.

https://cimg6.ibsrv.net/gimg/www.mia...6fb798dfe.jpeg

Just... main relay? The car started a few days later so I don't think it's the main relay

I have found them to be intermittent before failing completely. Kept one in the glove box. It is one of the weakest points in the system.

Ahhh okay that makes sense. I'll check out ways to test for that alongside the CAM sensor! Thank you for your input!

cam sensor is known to fail, ecu doesn't really matter. I'd recommend to keep a spare on standby along with a spare main relay.

Awesome, I'll order both and keep them on hand, I appreciate everyone here helping me with this and I'm glad to hear that it's likely these 2 sensors in stead of a laundry list of other problems

Yes, known issue, 90% of the time it is the CAS, otherwise it's the one on the crank, or the relay. I have spares of all three in the car at all times, because old car!

Good to know!

Just wanted to update this thread, I changed out the Main Relay and the car ran very well (idled better and everything). Still haven't had any issues since installation so I'm going to pin the main relay for this one since the car runs much smoother. Will be replacing the cam sensor as well since I ordered it but thanks to everyone that chimed in!

Okay, so Olderguy wins. :likecat: :likecat: