ECU not turning on
 

I've been fighting with my 1995 Miata and the FM2 turbo kit for a while now. Randomly lost power to my ECU now and I'm not sure what is going on. Here is where I'm currently at:

FM2 kit installed professionally by a performance shop but the guy wasn't comfortable with the ECU and tuning etc. Along with the turbo install I had him put on an ATI Super Damper with FM's 36-2 trigger wheel and FM's Big Flex Fuel kit. Trailer the car home and verify the work. Hydra Nemesis ECU is plugged in but WBO2 is not installed. Install and wire in the WBO2 and connect to my ECU. Get proper readings and attempt to start. No fire and plugs dry. Do some internet research and become enlightened to the fact that a 1995 Miata doesn't even have a Crank Position Sensor to read a 36-2 trigger wheel. Yeah you guys are probably cringing hard. Order a 2005 CPS from local Miata dealer and wait.

Tap threads into the already present hole for the CPS on my oil pump. Mount CPS. Disconnect battery. Splice into CAS per FM instructions and run Power, Ground, and Trigger down to new CPS. Reconnect battery and connect Hydra to laptop. Attempt to start and nothing. Re-run the trigger test and find that I now have the needed Trigger signal but no longer have SYNC that I previously had.

Disconnect battery. Cut into my electrical tape wrapped splicing to find that the Ground wire for my CAS came out of the two-way crimp electrical connector. Grab better connectors with heatshrink and re-do Power, Ground, and Trigger connections and heat shrink everything so all connections are rock solid.

Reconnect battery and pray everything is working (day three now of the "first startup" of new turbo after getting it from the shop). Key to ON position and plug in Hydra into laptop to get ready to run trigger test. Don't hear the fuel pump prime. Laptop doesn't connect. Look down at dash and see that the CEL light is not on. Couple hours later of internet research tells me that with key to ON position and CEL not lit means the ECU is not powered on.

Interjecting here to state I have a second bone stock running 1995 miata. Start checking all fuses to ECU including main relay. No blown fuses under hood or underneath dash. Remove Main Relay that I read over and over was the culprit. Plug it into stock Miata that is running and the stock miata fires right up indicating main relay is still good. Check secondary emergency main relay in working miata and it again fires right up. Try all three working Main Relays in non-working turbo build and confirm CEL does not engage / ECU does not power on.

So ECU was working at one point and now it isn't...Pull up wiring diagram to ECU and confirm 12V at pins BD-01 "MAIN RELAY" and BC-01 "IGNITION B+" which appear to be the ones providing power to ECU. Both pins show 12V with multimeter with key in ON position.

Disconnect battery. Reconnect stock ECU to stock harness. Reconnect battery and key to ON position. CEL light illuminates on dash indicating stock ECU has powered up.

Never experienced any smoke, smell of burning plastic, and no wires into ECU appear burnt indicating I somehow fried the Hydra. Not sure if this is still a possibility that I fried it.

My next and only option is to "bolster" the ground of the Hydra ECU and hope it somehow was not grounding correctly. Not sure if this matters but I do not have the mounting bracket for the Hydra so its just laying on the floorboard behind passenger seat. Its my understanding, and my understanding is very limited, that the ECU is grounded through the harness and the "bolstered" grounds are optional. I'm not sure if bolting the ECU would somehow help ground it vs having it laying on the carpet or if its strictly grounded through the wiring.

Any other suggestions besides "bolstering" grounds to ECU and hoping it starts turning on? Possibility I somehow fried my ECU with all the disconnecting/reconnecting of the battery and failing to properly ground CAS sensor? Again no smoke, no burnt wires, and no blown fuses or main relay. I'm throwing in the towel as I have work but I'll be back with the car attempting to add those ground wires on Wednesday. Any other suggestions between now and Wednesday would be appreciated. If ECU doesn't turn on with added grounding then I'll be calling up Jeremy at FM.

I haven't even started fighting the tuning on this beast or gotten my Flex Fuel sensor calibrated and hooked up...

Have you tried calling FM or talking to Ken Hill? Either of those would be your best bet

Yeah just as an update I added those grounds and still had the issue. Contacted Jeremy at FM who had me send it in. He tested it and got same results...dead ECU. Its currently back at Hydra for repairs. Still no idea what happened, how it happened, or how I can prevent it from happening again. Will give a final update if I get some answers.

Is the ECU new or did you buy it used?
When the ECU comes back from Hydra, ask Jeremy what caused the ECU to not power up. The answer may help you find the issue in the car, if there is one.
The bolstered grounds are not necessary, but I strongly recommend you make them. The ECU laying on the floor behind the seat should not have caused the problem. The ECU circuit board is insulated from the case. Unless, this was the problem with your ECU. In this case, Hydra will fix it. Still there is no good reason not to properly secure it to the rear bulkhead.

Where are you located?

Final update on this issue. Hydra repaired the ECU and told Jeremy they replaced the "main processor." Based on what I stated above they do not believe the failure of the processor was anything to do with what I did. Because of this they were not able to state why the processor failed. I may have just gotten a lemon but regardless the issue was fixed and the ECU sent back to me at no cost. The ECU is brand new not used. Received the ECU on Monday. ECU will be going in the car later tonight and hopefully fingers crossed I'll get it on the road. Jeremy also threw in the ECU mounting bracket. Feel free to lock this thread or even delete it as it has no value to troubleshooting issues with the Hydra. Seems to have been a random failure of an internal part not due to my installation.