alexaltima

I have a 1996 Nissan Altima (hand me downs to my son) which I recently replaced the engine from a 1997 (yard). The engine is surprisingly strong, the car runs great, startup fine, idle perfectly. However, when I first start it up, the RPM’s come down (very briefly) to 300-400RPM before settling back to the right number. The problem is that the check engine light goes on with a 2-long 5-short error indication that points to the IACV (idle control). Things I did:

Replaced the "new" engine's control with the old one.
Replaced the temperature sensor.
Replaced the TPS sensor with the "old" one.

Any suggestion, I’m out of ideas.

Thanks Much,