[TechnicalPixels]

Hello!
Thanks in advance for your help.

My issue:
I have a 2005 WRX. Non STI. Auto Transmission. 2.0L
Unfortunately the engine blew and we had to replace it.
We ended up getting a 2005 WRX 2.0L JDM engine.
We installed the new engine. All fluids changed. Water pump replacement. We replaced the belt on the front of the engine and did spark plugs before we installed the engine. We used the JDM engine harness but it has the UDSM ECU/ECM
Got the engine in. Starts and idles just fine.
However when we give it gas or any acceleration it will rev up and then starts to die. The car has not a ton of power either. The exaust also smalls a ton like it's burning super rich. Gears and everything work fine. Took it to a shop they said it has a clogged cat. We removed the cat and it's not clogged. Even replaced and still having the same issue.

What is wrong? Or any ideas of what we could try?

2 things we noticed.
The JDM engine has AVCS and the UDSM one doesn't.
Using the UDSM ECU we have no error codes at all. But also unsure it would have any issues running with the old ECU.

Please any help would be greatly appreciated!!!!

 

[Jedi03]

having avcs with no control for it would cause idle issues I would imagine...normally when I do these kind of swaps I move all the USDM sensors over for the off chance that the readings are different...