I have a 2000 civic si with a b18c5 swap running with a p73 ecu. The car is throwing the code 1071. running lean(bank 1) had the car smoke tested for a vaccum leak and an exhaust leak. There are no vaccum leaks or exhaust leak before the o2. i have a new fuel filter. Any help would be greatly apprecited.

 

You might need an oxygen sensor. A vacuum leak will cause it to run lean. Check the intake manifold and sensors on the IM and make sure they are tight.