My brother's 94 Z28 just failed emissions. He failed HC (needs 117 got 2000) and NOX (forgot the numbers) any idea what causes those numbers to be so high? The car has shorty headers, a cc304 (not sure if it is tuned or stock tune how can you tell on a 94?) and the usual bolt-ons to back those up (cai, etc). I believe that the AIR system is gone and the EGR might not be working, but could that cause such high numbers?

My dad said he saw an unpluged senser on the drivers side, that was just hanging near the fuel lines and looks like it needs to connect to the engine block, I have yet to see it, any idea what that could be?

Thanks for the help.

 

between everything you ahve said... yeah that will do it.. if the cam is not tuned ocrrectly and it;s running rich tat will do lot of it. AIR system doesn;t mater that much as long as you get teh car hot first. EGR should be working correctly if you wnat it to help. things that are especialy important are the way the motor runs and the 02 sensors. they say a califorina test showed that over 70% of teh cars that failed a test was due to 02's..

 

Yeah I was going to replace the O2s for him when I get back home just to make sure it wasn't them. Anything else?