I just got back from the smog shop and tried something similar to what you suggested. I plumbed in a second vacuum line into the line which runs into the EGR and it did drop the NOX to near nothing but it created an internal vacuum leak. So I passed everything except the HC part. Because I created an internal vacuum leak by opening the EGR all the time it was miss firing on the 25 mph test and dumping fuel so it ran super lean and failed the 25 mph test. At least I made improvement and I am not failing both the 15 and 25 test.
oh...this is a dyno smog test. that trick usually works for me cause up here in norcal we don't do dyno tests...what a headache huh..goodluck.
