View Single Post
Old 01-28-2020, 02:15 PM   #83 (permalink)
Cyborg ECU
California98Civic's Avatar
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 5,613

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 59.47 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,069
Thanked 1,778 Times in 1,205 Posts
Originally Posted by jimmylomax View Post
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.
I think these are pretty interesting points and I think I will put the downstream O2 disply onto my UltraGauge on the dashboard. I am pretty sure mine jumps around too. But I am not surprised, since the car passess smog but is not as clean as new. Clearly, my unit is within tolerances tho not optimal.

My moments when the CEL has returned, and generally whenever it showed up, were NOT during EOC. They were after significant stretches of steady throttle. I do more of that in recent years on freeways than once upon a time because I have a 0.710 fifth, 3.25 FD, 15" rims (12 lbs), and 175/70-r15 tires... so it cruises flat ground getting remarkable FE... not much benefit to EOC in such conditions.

See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

  Reply With Quote