Ok so I miserably failed emissions again because of NOX.

I am getting about 1.5' hg of ported vacuum from that little nipple underneath the Throttle Body when the specs say I should be getting at least 7" at 2000 RPMs. I have thoroughly cleaned out the throttle body and the passageways leading to that nipple. What is happening?

1. Is it possible my throttle body is leaking? would that effect ported vacuum?

2. I have my plenum ported would that affect ported vacuum?

3. Would my Airfoil be causing a problem?

 

1. sorry i dont know
2. my ported plenum never caused me a problem
3. my airfoil didnt either

Hope that helps a little bit... sorry i dont have any more info for ya

 

Are you measuring at that port directly without anything else connected, like the EGR line?

Try 3000 RPM, maybe the throttle isn't opened enough to uncover that port at 2000 with no load to get full vacuum. You're doing the test in Park, right?

Is it running really really rough? Doubt it, since it's only failing NOx, but have to ask i guess.

I can't imagine the other things like ported plenum or Airfoil changing the effects of ported vacuum in any way.

Check your base timing - too advanced will hurt NOx. But I'm betting it's an EGR issue or it's not getting into closed loop and is a little lean, or the cat is dead and the engine is in good enough tune for the HC to be ok and the limits are a little loose on CO (like a little over 1.2-1.5%).