More Info on Mazda engine cutting out: when the engine cuts out the following happens:
1.The rev counter stops working straight away
2.The ignition light stays on
3.The engine will still turnover
4.There¹s no spark at the plugs The engine will not cut out when the car is stationary

Is there a tool to get the code form the diagnostic socket available? (3/00)

This sounds a little similar to a problem I had with my car. One day it just wouldn't start. Engine turned over but no spark. Turned out to be the coil pack had died. I'm not saying this is what is wrong with yours (not even sure if an intermittent prob on the coil pack is possible) but it's something to check and hopefully you will get to the prob by process of elimination.

Ways to check coil pack:
- swap with another car which you know works ok
- get a *good* car engine management specialist (injection specialist) to rig it up and check it for you - this is quite feasible - I have seen it done and it proved mine was duff

The bit about no movement on the rev counter sounds very familiar to me. Not 100% sure of the 1.6 system but on my 1.8 the rev counter (and ECU) rely on signal from the ignitors, so if your ignitor is duff your rev counter will not register. You should also get the symptom of dry plugs (no fuel in the cylinders) because the ECU will not open the injectors unless it knows a spark is being produced, which it knows by the signal from the ignitor.

This should help narrow things down a lot. There are only a small number of connections to the ignitors. If I remember correctly there are four on each (of two) on my 1.8. I think they are +12v, GND, signal from ECU to spark, return to ECU + rev counter. If you use an analogue electrical tester you should be able to detect whether the ECU is creating the signal to spark. You need to use an analogue gauge (one with a needle) because it is too fast for most digital gauges to register. Have you got a wiring diagram? If you need one let me know and I will see what I can do.

If you can detect the signal from the ECU I think the ignitors are gone. This would seem to make sense with the engine cutting out after 10-20 miles - the ignitors are warming up and then failing. Have you ever left the ignition on without the engine running? This kills ignitors. The only time I ever do it now is for the short length of time it takes to put the electric windows up/down.

If you cannot detect the signal from the ECU then it may be missing a signal from one of the other sensors. I'm sorry but I don't know a great deal about these.

Brief thoughts though:
- the ECU needs a signal from the camshaft position sensor so it knows when to spark
- the ECU needs a signal from the airflow sensor (otherwise it cuts fuel off?)

BTW You have the 1.6 whereas I have the 1.8, but I believe the systems are basically the same. (3/00)

Do you mean that your car stops completely ? ie. total power-out affecting engine, lights, radio, and so on ? If so, it sounds like it's either your ignition switch or the battery connections.

Check the battery first as that's easiest (remember that it's in the boot !)
Make sure it is firmly secured/bolted down, and that the two connections are FIRM and CLEAN. If in doubt, undo them and clean them with sandpaper or something. Don't let the leads touch the bodywork or the wrong terminals or: fireworks !

To check out your ignition switch/barrel: undo the cowl around your steering column and have a look at all the connectors under there.

My guess is:
(1) one of the connectors is loose
(2) one of the wires within one of the connectors isn't as strong as it should be
(3) the ignition barrel itself is worn (I've read about this before but can't find any detail on www.miata.net)

With the radio or engine switched on and the cowl dismantled, give the wires, etc, a good tug to see if there's anything loose. If your radio/engine goes off, I guess you've found the general problem area. (3/00)