I have a 99 civic SI (EM1) and it failed smog do to nox being to high! The car runs great though...

Basic info

Crower Built Head
Valve Springs
Retainers
Stage 1 ctr Style cams
DC 4-1 Header (heat wrapped)
Revolution intake
Stock exhaust
oem catalytic conv. (Unknown Mileage)
132XXX miles
Fresh NGK plugs
New cap
New rotor
New wires

Any advice? I need to lower nox its suppose to be 487 at 15mph car runs 852

NEED HELP!!!

 

Just knock back the timing, get it tested and after it passes set the timing back to spec.

 

This can happen when the engine runs too hot or too lean.