Limp mode, Immobilizer, bad tune, or fried ecu after e85 tune?

[cornjuice]

Hey all,
New to audizine and hoping for some input. Hope to help others down the road when I can. Seems like the b5 super forum and more.
I've assembled a few stage 3 B5 s4's in the past and recently finished motor refresh with rods and such for my new e85 build. It's a 2000 b5 s4 6 speed with all the goodies and srm k24/rs6 hybrids. It passed emissions last week with flying colors in stock form. I put all the stage 3 Parts on and obviously ran a little hard getting to the tuning shop. I'm using a stock ecu from a 2000 a6 6 speed that I used to pass emissions. I broke the ecu tab off so it would fit the s4 harness. The ecu number is 4BO 907 551 K with a date of 04.01.00. We flash a base tune and start logging. We ran of time and I went home happy until we could do more logging and crank the boost up. On the way home, it starts chugging and the cel came on. Got home shut her down and now she won't start and run. Popped in another stage 3 computer and she fired up with no hesitation firing healthy on all cylinders. Brought her back to the tuning shop and swapped back in the ecu that seems to have gone south on me. Clear codes that were basically misfires, icm, and coil related. Still ran like it was on 2 cylinders and shut itself down after 30 seconds. We performed a quick reflash of what we had achieved the day previous and she came back to life. Even accepted 5 more pounds of boost. Took a few pulls, everything felt great until I shut her down when I got home. Tried starting it soon after and she went back to running on 2 cylinders and died after 30 seconds. No cel's are popping up. Trow back in my backup stage 3 ecu, she fires right up healthy and I park it in the garage. What the hell is going on? It's rejecting the tune or something? Limpmode?
Sorry for the long winded story! Any input would be much appreciated...

[vavJETTAw36]

Sounds like limp mode because of the tune. If you are in the U.S., we don't have immobilizer.

I'd plug it in and drive it until it does it again. Then unhook battery for 10 min and that should reset the Ecu. If it runs good again it's probably limp.


Sent from my iPhone using Tapatalk

[cornjuice]

I did unhook the cables/ecu over night and still remains in limp. Not driveable. Not enough power then dies often 30 seconds. Bought the ecu on ebay, out of 2000 a6 6 speed, that's what the listing said. Not ready to blame the tune yet but have no problem doing so...the codes that were thrown previously covered the entire board. All runs and reads perfect with my known good spare ecu's.
..