I have a 1993 EG hatch with a JDM GSR OBD1 ECU. The other day on my way to work my car threw a check engine light and was running like crap. its been sputtering for a while but I could never isolate any major cause. The check engine light is for the MAP sensor. I tested the sensor and found it getting 4.96V at the sensor going in and 44 mV coming out of the signal wire. I swapped another sensor in and found it to be the exact same thing. It threw the check engine light every time it was started. I checked continuity and resistance for all the wires at the ecu and sensor plug. All checked out at 0.1 ohms. I pulled the spark plugs and they we all black. Two fouled out during testing. Upon putting new plugs in and starting the car for about one minute the plugs became blacked again. I swapped in a pr4 just for testing purposes. I saw 2.96V on the signal wire at the plug. I started the car and it idle for a minute with no check engine light. I revved it up a bit and the light came back on and it idled like crap. I checked the signal wire voltage and found it to be 44mV again. I started tracing the wiring and the signal wire broke with a little bit of pressure put on it. Now I am wondering if these ECU's are fried or is there a way of fixing this issue without replacing the ECU? And how can I be sure that is the issue without destroying another ECU?

 

Open the ecus up and see what resistor or capacitor has burned out. Check both sides for burnt spots