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Old 01-28-2020, 01:08 PM   #82 (permalink)
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Join Date: Jun 2014
Location: St. Louis
Posts: 16

Red FIRE Racer - '08 Honda Fit Sport
90 day: 48.54 mpg (US)
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Originally Posted by California98Civic View Post
I don't think it was the EOC as much as perhaps burning a little oil through the valve guides and/or oil control rings. In EOC maybe the leakage does not have as severe an affect on the CAT's efficiency as when the engine goes constantly for 30 mins and more. My second recurrance was under high load climbing a mountain pass into the high desert, so... pretty hot and probably oil burning?

My 1998 Honda has no CAT temp sensors. Wish it did. Some things remain a mystery to me...

You are going to "boil your CAT in acid?"
I'm not doubting or questioning the source of the cat efficiency losses. I guess I'm questioning the detection. I am wondering if the reason mine hasn't been throwing P0420 is because it takes at least 15 minutes of running without an engine restart for the OBD diagnostic to perform and fail the test before throwing the trouble code. I threw my OBDII scanner on yesterday and graphed my downsteam O2 and it seems clear to me I do in fact need to give whiskers a bath of acid. Here is a plot at steady load and speed at 60mph showing my downstream O2 all over the place (which I believe in indicate of a poorly functioning catalytic converter... EricMyCarguy indicated it should hold flat at 0.5v meaning o2 inside and outside exhaust is 1:1)

RE: measuring exhaust temp, I don't think most cars have that sensor - I meant with an infrared handheld gun.
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California98Civic (01-28-2020)