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Power FC - Connection Error car wont start

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Old Jul 23, 2023 | 07:34 AM
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From: Terndrup
Power FC - Connection Error car wont start

New day new issue it seems….


Today I drove the car home from the workshop I have been working on it. All good and the car ran as expected.

I got home and washed the car as I think it was deserved after 8 months standstill.

now the PFC commander says “Connection Error” and the fans turn on. Car will turn but won’t start?

I have checked:
- ECU for loose connectors. Plugged and unplugged twice
- all connectors are bone dry
- battery voltage (12,5V)
- ECU print - does not look fried.
- all fuses look fine

What can be wrong? The car is giving me headaches and sleepless nights.

Mike
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Old Jul 23, 2023 | 10:19 AM
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Likely the power fc died. Not uncommon. You'll need another one to verify
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Old Jul 23, 2023 | 10:47 AM
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From: Terndrup
Originally Posted by FDAUTO
Likely the power fc died. Not uncommon. You'll need another one to verify
also my first thought. Still hoping for a better diagnosis.
Don’t know anyone driving RX7 let alone PFC near me (located in Denmark).
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Old Jul 23, 2023 | 06:56 PM
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Oh man... bigger problem, even if you got another power fc do you have a datalogit?
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Old Jul 24, 2023 | 08:24 AM
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From: Terndrup
Originally Posted by FDAUTO
Oh man... bigger problem, even if you got another power fc do you have a datalogit?
nope, no datalogit either
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Old Jul 24, 2023 | 11:11 AM
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From: https://www2.mazda.com/en/100th/
do you have a stock ecu to try?
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Old Jul 24, 2023 | 11:34 AM
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From: Terndrup
Originally Posted by j9fd3s
do you have a stock ecu to try?
Unfortunately not..
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Old Jul 24, 2023 | 12:25 PM
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youre kind of stuck here. youre only real option is to buy another ecu. its extremely unlikely there is another problem causing what your issue. the most difficult part is the lack or resources to do anything. youre going to want to buy a datalogit or a more modern ecu if you want to continue your FD ownership. at a minimum there are some really good threads here on power fc usage and tuning that you could do for yourself what you cannot obtain locally.
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Old Jul 24, 2023 | 02:42 PM
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From: Terndrup
Originally Posted by FDAUTO
youre kind of stuck here. youre only real option is to buy another ecu. its extremely unlikely there is another problem causing what your issue. the most difficult part is the lack or resources to do anything. youre going to want to buy a datalogit or a more modern ecu if you want to continue your FD ownership. at a minimum there are some really good threads here on power fc usage and tuning that you could do for yourself what you cannot obtain locally.
Yeah, also feels kinda stuck now.
was planning on upgrading to Haltech in the winter anyways but was hoping to drive the car for the rest of summer without issues.

If I were to source a datalogit it should be possible to see if the ECU is dead? The theory of dead ECU is still only qualified guessing I suppose.
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Old Jul 24, 2023 | 03:33 PM
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a dead power fc will still allow the datalogit to connect in some cases. in other cases it will not. it really depends on how it failed internally whether or not it will allow for a connection. if the commander cant establish a connection with it then it will be likely the datalogit will not either
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Old Jul 25, 2023 | 01:39 AM
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From: Terndrup
It may be easier to find a stock ECU to verify the PFC is fried. But would the stock ECU even work
when I am running single turbo, rats nest delete, OMP delete etc. or does it have to be and
PFC?
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Old Jul 25, 2023 | 08:23 AM
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From: https://www2.mazda.com/en/100th/
Originally Posted by mluu92
It may be easier to find a stock ECU to verify the PFC is fried. But would the stock ECU even work
when I am running single turbo, rats nest delete, OMP delete etc. or does it have to be and
PFC?
stock ecu might not be happy, but it would work. you're just verifying that the ecu is the problem
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Old Jul 25, 2023 | 08:33 AM
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From: Terndrup
Originally Posted by j9fd3s
stock ecu might not be happy, but it would work. you're just verifying that the ecu is the problem
Exactly. It would only be with the purpose of ruling out other issues.
thanks! It should be easier to find a stock or PFC rather than PFC only
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Old Jul 25, 2023 | 09:14 AM
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No rats nest, no omp, likely much larger injectors..... it won't even start. It will definitely crank but it won't start. If you had stock injectors MAYBE it would try and turn over but with different injectors the stock ecu is useless
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Old Jul 25, 2023 | 10:01 AM
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From: Terndrup
Originally Posted by FDAUTO
No rats nest, no omp, likely much larger injectors..... it won't even start. It will definitely crank but it won't start. If you had stock injectors MAYBE it would try and turn over but with different injectors the stock ecu is useless
4x850cc injectors. Secondary are stock and stock secondaries in primary
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Old Jul 25, 2023 | 12:08 PM
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with that, you have a chance of it starting. if it does, it will not be good. the stock ecu will be hit with so many errors and it will be in limp mode. i guess all you need is for it to fire off to confirm the suspicion. its worth a try
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Old Jul 25, 2023 | 12:11 PM
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From: Terndrup
Originally Posted by FDAUTO
with that, you have a chance of it starting. if it does, it will not be good. the stock ecu will be hit with so many errors and it will be in limp mode. i guess all you need is for it to fire off to confirm the suspicion. its worth a try
Worth a shot! If anything I should be able to hear fuel pump running (which it does not do now) and my fans won’t be running. If that is the case I think It is safe to say the PFC is fried.
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Old Jul 25, 2023 | 12:16 PM
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the non priming fuel pump is usually the biggest giveaway the ecu is dead
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Old Jul 25, 2023 | 12:21 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by mluu92
Worth a shot! If anything I should be able to hear fuel pump running (which it does not do now) and my fans won’t be running. If that is the case I think It is safe to say the PFC is fried.
open it up, maybe it would be literally fried
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Old Jul 25, 2023 | 12:58 PM
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From: Terndrup
Originally Posted by j9fd3s
open it up, maybe it would be literally fried
already did. Nothing to see
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Old Jul 26, 2023 | 09:35 AM
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First off I kind of doubt the PFC died. Really they are pretty hardy.

You need to do some troubleshooting as to what the engine is not getting that is causing the no-start. Fuel pump running? Ignition firing? Fuel injectors firing?

I would also look at whatever has changed between when it ran fine and now, whatever was touched is most likely the culprit.

Also probably worth doing a fuse check as well.

And dumb question - you spoke about washing the car. You didn't move the car out of the garage, shut it off when cold, wash it, now it won't start? Like you may have flooded it?

Dale
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Old Jul 26, 2023 | 10:08 AM
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^^^^ Indeed.

If the power comes on and you can check sensors and such on the commander, it seems more like a relay, fuse, or exposed connection got wet when you washed it. I HAVE had a PowerFC go bad, but it didn't manifest like that.
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Old Jul 26, 2023 | 03:12 PM
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From: Terndrup
Originally Posted by ptrhahn
^^^^ Indeed.

If the power comes on and you can check sensors and such on the commander, it seems more like a relay, fuse, or exposed connection got wet when you washed it. I HAVE had a PowerFC go bad, but it didn't manifest like that.
Already checked all of the above. And can’t check anything on the commander since it is dead (showing “Communication Error”).

I just sourced another PFC for testing and fuel pump primes and everything seems normal - which was not the case with my own.

I think it is safe to say my PFC is dead.
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Old Jul 26, 2023 | 04:24 PM
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Yup, sounds like it.
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Old Jul 26, 2023 | 04:33 PM
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From: Terndrup
Originally Posted by ptrhahn
Yup, sounds like it.
Was planning on going Haltech. Guess this is a gentle push in that direction
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