sooo here we go....again....95 z28 camaro wit 160 k miles on it......just tried to do emisisions for the second time and i failed once again....heres my problem
replaced cat
now i am failing the load part and i passed the idle part....since i keep having an o2 sensor failure come on showing lean?? ive checked it out and it seems to be ok...ive even put a new one in....soo i did a vacuum check, and its reading at 16 psi, and it says late ignition timing?? what does this mean??????thanx alot for any ideas.........

 

Do you have a stock cam?

16 Hg seems way to low. I would think you should have about 20 Hg at idle. You might have a vacuum leak. I think you would have a rough Idle and wouldn't pass the Idle test. Have you done a compression test? you might have a low cylinder.
When was the last time you replace the PCV vavle?

just some ideas, not sure if they will help.

 

welll pcv valve...........never........but its worth a shot....i mean i do have a bit rough of an idle, and a slight studder in low rpm crusing around 30 to 40mph.........soo possible......but i just dont understand why it would come up o2 sensor lean?????? is that a vaccum that is tripping it????

 

I would think it would be that the MAP sensor is seeing a lower reading and using a different fuel table. just guess here though. You can also use carb cleaner and spray around the intake manifold to see if it is leaking. The PCV valve could be broken and running wide open. Which, would lower the manifold vacuum. It also won't meter the amount crank case blow bye. It might be enough to make the engine dirty at cruse speeds..

 

go register in a county without e-tests!