Hello all, I have a 1993 civic dx with a JDM D15B engine. I can't be sure if it has every passed emissions but it is hitting high on all marks. Since the engine has been swapped out I can't tell what goes where. Can someone help me figure out if I have a vacuum leak? How can one troubleshoot vacuum leaks?

 

Failing on all 3 pollutants usually means the cat. converter is bad. It does have a converter, right? Even if there is a converter mounted you should drop one of the pipes and check that it has not been hollowed out.