Even before dropping the 13bt in, my 88 vert always idled rich once it warmed up. Around 11 or so. I can tune it back once warm, so I keep it around 12.5 to 13. Then, once I shut it off and let it cool down, it's too damn lean to idle when I start it again.

Like I said, I've since dropped in a TII engine/trans, put in a Walbro 255, stock vert ECU (no problems at all, except this one), SAFC (just for fine tuning) stock injectors, NGK wideband.

I'm not convinced that the vert ecu is the problem. I have a spare, and it does the same thing. Additionally, the problem has persisted since way back when it had the NA engine in it too. It's not having any problems with detonation under boost, it pulls hard and strong, AFRs when boosting/driving are perfect. ECT sensor is new, I've ohm'd the wires to the ecu and everything's good.

It just almost seems like it's never getting out of open loop, but the initial set coupler is not jumpered.

 

Wouldn't your vert ecu (both of them) be pulsing the injectors as needed for the factory N/A injectors-460cc- but that pulse is actually applied to the TII 550 injectors. I would expect about 25% too much fuel to be injected at any one point.

That would be why it is running rich. Pretty straightforward.

Maybe I am missing something here...