Got headers, TP, Y-pipe and catback! Can hear an air leak and feeling this CAMs-style roughness!! The RPM drops and the car nearly stalls!!

feedback is appreciated

 

YES. Leaking headers will let air get in before the front O2 sensors (which are widebands, BTW) and make the car read richer or leaner than actual. This could yield funky closed loop A/F corrections for one side or the other and give you the situation you describe. It isn't to say that the car is simply adapting to the new complete exhaust, but I doubt it. An OBD2 scanner will tell you if the closed loop correction for one side or the other is way off, etc.

Mark

 

03 Models do not have WB O2 sensors...

 

My bad. I was speaking from my own Z which I've been around quite a bit. Didn't know that. I have a bastard 04.5 so it's a little different than most. Regardless, the same issues will result from leaking headers.

-Mark

 

wait...then what are the sensors that go into the cats? those aren't wb 02 sensors???

 

thanks

 

could also be a vacuum leak causing the ruff idle

 

i'd say vacuum leak more so than exhaust leak.....just make sure everything is tight

can you hear the exhaust leak?

 

I can hear the exhaust leak and smell fuel somtimes!

 

sensors on the headers???

 

yea there are sensors on the headers, i put mine in so i know that at least the 03 ones do

 

Problem found!
A CRACKED plenum!!!!!

 

what kind of plenum was it??

 

My old nissan 200sx was so vacuum sensitive, pulling the oil cap off while it was running would cause a rough idle and make it almost die.