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Old 07-01-2013, 11:07 PM   #1
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Default engine swap and now nothing

whats up guys. i recentley bought a 91 miata that was turbo'd on megasquirt. the motor had low compression in two cyl so i ended up replacing the motor and putting the stock ecu back in the car. now my question is when i turn the key i have absolutely nothing...the fuel pump turns on but i have no dash lights at all...almost like these is nothing there. no starter click etc. The ecu does look a little haggard...it was givin to me with the car. any idea what it could be? does it sound like a bad ecu?
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Old 07-02-2013, 12:41 AM   #2
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anyone?
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Old 07-02-2013, 01:46 PM   #3
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ecu might be done. are any of the accessories working? radio, lights, etc
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Old 07-02-2013, 01:57 PM   #4
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start by checking all fuses, relays, and any wiring you may have touched during install/removal of ms.
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Old 07-02-2013, 02:22 PM   #5
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if it was megasquirted before, it's probably missing the st_ign fuse.
why are you even installing the stock ecu?
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Old 07-14-2013, 04:52 PM   #6
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i am returning the car to stock...i looked and the st_ign fuse was missing. i threw a 10a fuse in there and still nothing. i dont even know where to look anymore. i also have no power to hvac controls.
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Old 07-14-2013, 04:57 PM   #7
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you're probably missing more fuses
look in the owners manual or the inside of the fuse panel and check each one
make sure correct size and that there's a fuse in each space that needs one
then if that doesn't work check all the relays
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Old 07-19-2013, 12:00 AM   #8
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okay guys, i checked all of the fuses and everything is good to go. Im still at a loss. i checked the fuel inj fuse cause my buddy has a 91 miata and just swapped then and still nothing. when you to the key to the on position the fuel pump primes and then literally nothing after that. The relay does not kick on for the fuel injectors (only the fuel pump) but the relay is good..
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Old 07-19-2013, 12:02 AM   #9
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also...i know this seems like a weird question but what if this Ecu was from an automatic miata? I honestly dont know if it came from a manual car or not. anyone have any input on this? would the car still start?
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Old 07-23-2013, 08:20 PM   #10
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anyone?
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Old 07-23-2013, 08:45 PM   #11
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Do you have your starter wire and oil pressure sender leads switched? It happened to me when I did mine. It wouldn't crank at all, but everything else lit up and worked normally.
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Old 07-23-2013, 10:50 PM   #12
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I don't know what the problem is.

But it's something really simple.

Forget about the ECU. You can unplug it, throw it on the ground and smash it with an axe, and the starter will still turn the engine. Same goes for the fusebox- only the 80A main will prevent the starter from turning, and that's not blown or your fuel pump wouldn't be running.

This is more basic than that. You're gonna need to just start tracing wires. This is where a copy of the factory wiring diagrams is helpful.


Actually, now that I think about this, you're saying that the fuel pump was running with the key in the START position even with the ST SIG fuse missing? That's imposisbru.

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Old 07-24-2013, 09:41 PM   #13
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Ill trade you my perfectly working stock 92 ECU for your MS. lol
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Old 08-06-2013, 08:53 PM   #14
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Id say use the ms and ditch the stock ecu
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Old 08-21-2013, 10:00 PM   #15
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Alright guys, I am so lost here. I have the car running now. It will start but runs idles very rough. Almost like a misfire. Ever since I pulled the radio out of the car to fix a speaker wire when I first bought the car it ran this way from here on out. I swapped the motor cause the old one was ****. The fuel pump was constantly running before. But I found the plug and fixed that. Made sure the fuel pump was good. Changed wires, coil packs, CAS 2 times. I checked all of the fuses inside the car and in the engine bay and they are all good. I also still have no dash lights at all. This sounds stupid but would the factory radio harness being cut have ANYTHING to do with it? I have pulled the dash out and you can tell where some wires where tapped into for the MS but other then that nothing was cut ( besides factory radio harness). The main relay is good. I've tried 2 of them as we'll....I'm lost guys.
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