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MS3 Dead?

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Old Apr 7, 2025 | 01:16 PM
  #1  
tfbmiata's Avatar
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Default MS3 Dead?

Hey everyone, just got back from a track day at Sebring. Everything went mostly great, but the day ended off poorly. During my last session, even though I had changed nothing with my tune, it seemed like my ECU enabled boost control. I normally turn this off during track days and just run wastegate pressure. Anyhow, I ran with it just paying close attention to temps etc. Everything was fine, I came back to the pits and parked the car. About 30 minutes later, we decided to leave and upon trying to start the car, it would not fire. Starter turns over, but as far as I can tell no fuel or spark. There are some things I've done:
  1. Looked at every underhood fuse and cabin fuse and none look blown
  2. The car, when ignition forward shows a battery light (battery is fully charged) and the fans turn on. I remember this from my stock ECU days, this was like the jumper/diag mode right?
  3. Tried to connect to the ECU via my USB to serial and no dice
  4. Tried to leave battery disconnected for an extended period to 'reset'
I emailed EFI support, and they immediately said sounds like an ECU failure, but I'm hoping some of you might have some ideas to help me not spend $1,150 just to return my car back to working.
Old Apr 8, 2025 | 06:09 AM
  #2  
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It does sound like a dead processor, sorry for the bad news. The good news is that the efi folks (sounds like an ms3pro?) should be able to repair it for much much less than the cost of a new unit.
Old Apr 8, 2025 | 08:53 AM
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For those of you with your money on a dead main relay, you were right. I couldn't figure out how to test it and finally got one from a far off but local parts supply place. So, for future people, if your car doesn't start, and pushing the key forward results in fans and a battery light, its the main relay.
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