Is This a Bad ECU?

[NoahB116]

Hey guys. So recently my MS6 has been shutting off at idle for literally no reason and does not start back. So I did what everyone else does when their car doesn't start. So I made sure I had fuel pressure using my AP and I did, so I had fuel. I checked the battery and had plenty of power. Checked and had no big enough vacuum leaks to at least not make it start. So I narrowed it down to spark. I pulled the coil pack on the right put in a spark tester and grounded it and when I went to test the spark the car fired right up only on 3 cylinders??? I put it all back together and it worked fine. Now this has happened to me many times now and the only way to get it back to running is to use a spark tester. I have asked other Mazda people and mechanics and they all said a bad ignition system (which I'm pretty sure is built into the ECU on the MS6) which would need to be replaced. Can I get confirmation that this is what needs to be done?

(FBO minus mani's. Tuned on 93 by Justin from Freek.)

(TL;DL) My MS6 has been shutting off at idle. The only way to get it to start is using a spark tester which "back spikes" the ECU. Do I need a new ECU to do this?

[Jeff23spl]

the fact that it get ''repaired'' with the spark tester is a bit odd but sometimes there is no answers to strange things...
I had similar issues and after replacing the coil harness, i had to replace the plugs that was almost brand new but the misfire destroyed them....With new plugs, it finaly triggered a cel for the cam sensor, replacing the cam sensor and it ran fine but i wasn't able to do further tests as my turbo let go too....

I would put new plugs and carefully inspect each coils and check harness connection back to ecm...including the ground on top of the hpfp protecting plate...

The problem of replacing ecm is that it need to be programmed by Mazda to fit keys and cluster and i expect you would need to find one with the proper options installed but i could be wrong on this last part...