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I recently just bought a 2005 honda civic lx coupe manual and it had a 04-05 jdm d15b vtec engine swapped into it, it had d17a1 from factory. i’m getting a steady base idle at 2000rpms, and The guy that I bought it from said it's probably ecu related and I’m wondering if anyone has some info and can help on this. he also said it was giving a code for a Baro sensor when he installed it. my guess would be that the vtech not being hooked up it causing the idle to be so high. i would probably need to get a ex ecu and run the wires to the solenoid but ive never done that before and also wonder what that intails.

 
Rep Power: 125

It will be unrelated to it being a VTEC engine. It won't not recognize something that it was never programmed to read. It'll just run like a non-VTEC engine.

Idling that high (plus the code you mentioned) indicates some sort of air flow/sensor issue. If it coded immediately after the swap, I'm going to guess it's a vacuum leak.

 
Rep Power: 366

Many have dropped a VTEC engine into a non-VTEC model (hype) and ended up with a dead weight VTEC hardware and less power than VTEC/non-VTEC.
That said, the ECU have no idea what is a VTEC. It is just dead weight.
Your issues are not VTEC related. It is something else.