Interesting fried ecu problem
 

A customer of mine recently brought his Rx-7 back to the dealership for them to test the failed omp he had replaced there. The technician hooks up their OMP diagnostic box and they go for a spin. Out of nowhere the car cut-outs under partial load. I end up driving the car and notice the injector duty cycle flat-lines all of a sudden under heavier load. He sends the ecu out to be checked and a few of diodes are fried, $500 charge.

A year ago his omp died and the stock ecu quit on him. The omp quit again this time around( with the pfc), but the car run just fine for a weeks after we did his engine rebuild and only had problems minutes after being hooked up the mazda's diagnostic box. Car has had the engine harness replaced previously too..

Has anyone else heard of this problem?

The OMP & ECU must be changed at the same time. I'm in the middle of keeping the same ECU because I don't see any burn marks arounder the MOP Driver IC. But it looks like I'm going to buy a new ECU anyways from many searchs I've done.

Sounds like a wiring shorting problem.
The only time I have seen an OMP problem was due to it's wiring harness not properly tied down where it goes behind the aluminum water pipe.
The back of the e-shaft pulley rubbed against one of the wires and cut through it.

the one i've seen, had a bad ground in the harness, and the ECU used the OMP as the ground, which fries it, and the ECU, until the harness was replaced.

i've never heard of an OMP diagnostic box....