need help with emmisions
 

i cant seen to pass emissions
i tryed 4 times
put a new cat on
new o2
timming
it passes on all areas but fails on the CO% by double the limit
any thoughts
maybe to rich/lean
i have 91 civic with stock SOHC ZC

high Carbon monoxide would indicate the you are running rich. This would mean any factor that would cause less oxygen to be present or more fuel. Obviously fuel is a more common factor to go wrong rather then oxygen. I would test the following:

Fuel system
Ignition timing (you said you have already done), I would also check ignition components.



Fuel system:
-Fuel pressure regulator (simply unplug and if engine rpm increases then it works)
-system fuel pressure (need a gauge hooked up to the service port located on the top of the fuel filter located on the firewall)
-injector noid test (need a noid light to see if injectors are firing right and proper signal, basically a jumper light hooked up to the p2 injector plug)
-injector voltage (signal from computer)
-injector resistance (injector carries proper internal resistance to operate properly)


If all is within proper operating specs. i would then turn to using a lab scope on other vital sensors that play a key role in fuel delivery.

Personally you can only tackle the ordeal for so long until specialized equipment is neccissary to diagnos these kinds of problems. I had a similar issue at one time and swapped the engine out because i had a spare. I took apart the old one and there is a bent connecting rod. My car was burning tonnes of oil and i thought that it was the usual honda ordeal, until after changing valve seals and a few other things when i began questioning myself.
This is just an example of how emmissions diagnostics can be unpredictable sometimes.

Good luck:smilie_da

Thank You very much for the tips