kevlife

Greetings, I usually just read the threads to get resolution, but am at the end of my rope.

Looking for some insight here.
99 SI, B16A2 no mods to internals, but recent top end rebuild, currently 161k on the engine.

Running a Megan header and Magnaflow cat back with OEM cat.

Just recently I have had a CEL P0139 come on; Secondary O2 slow response.
I started by replacing the O2 sensor three times, no joy.

I am running rich, and have the legendary black/grey smoke when VTEC kicks in under high demand.
I had a local Honda only guy (not a tuner) do the top end work, (he sent the head to a local shop) install new rings, and do just about everything else he could do with the engine apart to that degree.
It feels as if I am losing compression OR it's just going into safe mode. Unfortunatley, there ar few Tuners in my area that I know of, and none the work with Hondas.

I'm thinking perhaps the rings did not seat well. I am also thinking header/cat issues (perhaps a high flow cat is needed?).

Also have been considering VTEC or cam stop issues based upon some forum chat here and there.
Otherwise I am at the end of my skill set and just do not have the time or space to start pulling things apart on my dd.

Also, If anyone knows of a good honda guy just north of Atlanta, please let me know.
Thanks!

rick_rabies

dang. did you do a compression test? do that first so its outa the way.
o2 sensor? as in primary or secondary?

if your state allows get some kind of tuning stuff and learn how to use the basics...and disable all that obd2 crap(no need for the 2nd o2 anymore if you do)

Former User

P0139 is for the secondary O2 sensor which, unlike the primary o2 sensor, has nothing to do with the fuel trim or your engine running rich. Are you installing an OEM secondary O2 sensor?

For the running rich problem, check the plugs, wires, cap, rotor and ignition timing. Compression testing the cylinders is also a good idea.

kevlife

The guy who did the head work also did compression, he said it tested good. A few years back I had a leak down done and it was "getting tired" hence the ring replacement when the head was off. That's why I was thinking the rings did not set well.

Not really due for a tune up, but will take a look at all that stuff.

The O2 sensor is OEM, (yes, secondary).

I just wasn't sure if all of these things added up could somehow throw this sort of code.

It's really running like crap. Oh, and it's using at least a quart of oil every three weeks with regualr daily driving.

I have seen many similar types of posts regarding these symptoms and am thinking I have multiple issues going on.