After just fixing my FAB9 COP wiring harness my Miata decides to die on a busy highway. Here's how my day went..

Spent the day fixing my FAB9 COP wiring harness (had to order a new one as the old one wasn't giving me a spark on plug 1). Fixed the harness and the car fired up like new. Drove the car around the city flawlessly for the majority of the day. Then this happens:

Driving on the highway at the average speed I begin to notice that my revs slowly began to drop. Initially, I could add more gas and watch the rev limiter bounce up, however, I felt no power. It felt like the clutch was slipping.. I could rev the car up but felt absolutely no connection to the road. Shortly after, the gas pedal wouldn't rev the engine up and the revs dropped to 0, stalling the car. I pulled over the car, checked all the wiring and nothing looked out of place. I attempted starting the car and could hear the starter motor working. It never caught. I stood outside of the car as I called for a tow truck. The service provider on the other end was taking way too long to take my details so I jumped back in the car and tried to crank it over again. This time it started flawlessly. I drove the car home from there as if nothing happened.

I'm extremely puzzled now. Anyone else have an issue like this?

I've had this happen to me once in this car before. I was driving on the highway when I lost power in the engine and it slowly came to a stall. However, I was able to crank the car over again and drive it home. I found out later that it was the catalytic converter that rotted and blocked the exhaust that created enough backpressure to stall the engine. This time however, I have a brand new cat which I can confirm has not rotted out.

Any ideas?

 

cas?

 

I just took the car on a 300km trip and it ran fine.

However, I did order a new CAS and will replace the old one.

Does the way the car die sound like a CAS issue? I've read that they have problems in the 01-05 Miatas.

 

Next time it acts up, try swapping to stock coils. I bet your problem is the coils, those coils are designed to be driven by a few hundred volts via a CDI, not 12V. The resulting "spark" with 12V power is extremely, extremely weak, and gets weaker when heatsoaked.

 

Did the stereo/lights/etc work when it was acting up? If not, then it's the main relay.

--Ian