Engine running rich, thinks it’s running lean...


Jan 21, 2018
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Smyrna, TN
My 2001 accord ex V6 coupe (j30a1) with 258k miles has been running very rich lately. The CEL will come on every once in awhile, but will go back off within a couple days. Live data is showing me that the O2 sensors think that the engine is running lean and is trying to compensate by adding fuel. The engine runs ok until you get over 3k rpm, then it feels like it’s loosing power - my top end is worthless. If you try to give it a heavy load, black soot comes out of the exhaust and you can smell it in the cabin. Both O2 sensors and the cat were replaced about a year ago. Unfortunately, I’m running an open cat because I couldn’t afford the rest of the exhaust.

Now, I’ve got some money for parts and it’s very slow at the shop so I can start looking into this. I fixed any exhaust leaks I found and made sure I didn’t have any vacuum leaks. I’m not a hardcore diag tech, but I understand the very basics. This isn’t an emergency, i can pass emissions, but any help is appreciated. :)