Subaru impreza v1/v2 wrx
 

Hi,

New to this and new to owning a Subaru.
I recently bought a Subaru which needed the engine replacing, I replaced the engine yesterday and got it running but after a few minute's the engine started to struggle on idle so I adjust the throttle slight to 900/1000 rpm but still didn't seem right and then the CEL came on so I turned it off check to see anything was left off, went to crank it and it afterfired and took a while to start up. I plugged the standard ECU back in, it had a stage 2 ecu when I bought the car.
Car also won't go over 20mph seem like it's in limp mode.
Hopefully someone has an idea.

You need to read the fault codes by connecting the 2 plugs under the dash and counting the flashes on the mil lamp. Theres a thread on here with all the codes and the process to get them. Have a look on the forum.

Cheers mate, the CEL only came on the once that day and never came back on would the code be stored?

Possibly, try reading the codes and see what it throws up.

Have you fitted a like for like engine?

What ecu's are you using? They all have codes on the cases.

Whats a stage 2 ecu? Never heard of that one.

Possibly an ESL mappable board fitted.