ECU Reset issue, I'm stumped!

[driftae76]

So heres the background.

'90 toyota cressida. Ive converted the engine to 1UZFE. Initially I had wired in the factory 1UZ Ecu using the cars original wiring and relays. Daily Driven for ~2 years with no issues.

1 year ago Purchased a Link G4+ Thunder(new). Wired it in to my existing wiring loom - kept the MREL power circuit and existing EFI Main & Circuit Opening relays from the Cressida.
Since then Ive been chasing this annoying intermittent issue where the ECU would reset momentarily every so often.
Naturally I thought It must be a wiring issue, bad crimp, bad earth etc. Ive been over it that many times. Now I've hardwired the ECU directly to the battery - The dedicated IGNITION input and the +14v inputs go DIRECTLY to the battery positive, and the ecu still experiences a power glitch - The engine stalls and PCLink looses its connection (which interrupts datalogging). Why is this happening? Surely if the ecu is experiencing uninterrupted 12v, PCLink should never lose connection, and the ECU should never power down.

I've sent the ecu back to Link for testing, they cant replicate the fault on the test bench.
So where does that leave me? Unfortunately I dont have a spare link thunder which I can swap over to prove whether or not its the ecu or the field wiring. Im basically stuck with a $2500 paperweight at this point

Attached is a log and config file. 5:09 you can see the engine is sitting there idling and then out of nowhere the engine stalls and PClink drops its connection, which then recovers and continues the datalog.

Hope some expert can help, personally I'm convinced that the ecu is faulty but I'm not sure how to prove it one way or another without a second one to try. And a test bench cant always replicate a real world scenario..

thu died.llg 1uz map.pclr

[Adamw]

It does sound very much like a power supply loss if connection is lost and engine stops at the same time. 

Where abouts are you in the world?  Was the ecu returned to NZ?  Whats the wiring/battery set up like in the car - battery in the boot/trunk or anything?

[driftae76]

Im in Brisbane, Australia, so the ECU was sent back to the Brisbane service department.
Intially the battery was in the engine bay in its stock location, I then relocated it to the boot hoping that might fix my issue alas it did not. (Im a sparky by trade, used 50mm2 pos and neg leads up to the front properly crimped, heat shrink distribution studs, single earth chassis bond and strap to the block.. all that good stuff).. Also ran the ecu negatives out of each connector plug individually to single ground point on cyl head, + separated+isolated sensor earths.. 

Is there any posibility of switching my ecu with a known 'good' unit for purposes of testing? or pay some sort of bond to obtain a loan ecu for testing? 
You can probably sense my desparation, I just really want to try to get this issue sorted :-)

[driftae76]

Thread bump. No ideas anyone? @Adamw?

[Adamw]

You can try talking to the AU office to see if they have an ecu they can lend you, im not sure what they have.  

Head office can do much more complete testing though so it would also be worth sending back to NZ if they dont have something they can loan you.  Probably even an Xtreme would be fine for testing.