I have a honda CRX DX 1.5L Auto Bone Stock
I had to get it inspected and this car sits all the time maybe 100miles per year
I fire it up and its running rough so thats expected I guess
Took it out for a drive and it threw a check engine. 1 blink on ecu which I believe is O2 Sensor
I changed the O2 Sensor (only has one upstream)
Testing in the Driveway Exhaust Soot still happened.. Heavy at times
Pulled a Plug and its soot covered O2 must be loaded with soot

When I first drove it the car performed ok but it seemed to be eating lots of fuel.
I am sure I burned through whatever gas was in it and put Premium in it so it should be ok.
It has a rough idle and rough acceleration in the driveway
All the plugs are fully soot covered and equally caked .. there is no oil on the plugs
Warms up but doesn't overheat.

When I changed the O2 sensor I did some maintenance
change the valve cover gasket because the plugs were sitting in oil. only in the tubes no oil on tip of plug.
changed the plugs and wires, Change the oil, filter, fuel filter, air filter.
Sprayed my vacuum lines with carb cleaner and don't see any difference so probably no leaks.

I am thinking it could be the fuel pressure regulator (expensive if i can get one) or maybe the PVC valve.
Not Sure What Else To Look For

thanks

 

this is the samething that happens to my 91 civic si. I have a zc sohc. I had to pass the state ref. The tps wires were wrong so I fixed them, 3rd gear would bog down and would throw so much black smoke out of my exhaust. After my tpd repair it stopped bogging and only throw black smoke at high rpms. I passed the state ref. And Now its happening again. I changed the fuel pressure regulator, new cap and rotor, new ntk o2 sensor, new fuel filter, throttle body, new charcoal canister, and map sensor, new tps sensor new catalytic converter, exhaust, and its still happening. So im lost as you are.