my nox is still high and i changed the cat, put timing back to zero, new 02 sensors, and still the nox is like 20 points higher. anyone have any suggestions also how do you get rid the trial thing below my screen name? I HAVE STOCK Z6 motor

 

To get rid of that trail screen name with for 20 days for full access. Until then sit back and read forums.

 

i would try the egr valve

 

they still got egr valves? if they do damn i dont know..haha but had all vcacuum lines checked and no leaks? could it be the injectors?

 

high nox is caused by high cylinder temp. usaully a bad egr valve, but there are some other thing like dirty coolant not cooling the cylinders properly, running lean for some reason like coolant temp sensor sending impropper signal to ecu, spark plugs etc.