I have heard of DC Headers releasing too much heat and not getting the cat
hot enough. I think NOx Generally points to the cat, but if you're pretty
sure it's good I'd lean towards heat loss. What I'd do is put the factory
cast iron exhaust back on there, and put the cat back in the factory
location. This will help it retain heat. Also, in the 10 minutes leading
up to the test, drive in a lower gear than you normally would. The higher
RPM's will help to heat it. When you get to the test station, don't shut
the car off. Stay with it, and preferably keep it revved between 2-3K.
Also, run the lowest octane fuel you can. This will promote a more complete
burn.
I did these things and mine passed, even with higher CR pistons and a cam.
I have to run 93 Octane in mine.
Dave Hardy
89 SM
----- Original Message -----
From: Yuri Klepach <civicr1992@yahoo.com>
To: <autox@autox.team.net>
Sent: Monday, December 17, 2001 3:29 PM
Subject: Failed NOx emissions. HELP!!!!
> Hi guys!
>
> My 1992 Civic just failed NOx emissions (1990 vs 1370 allowable). CO & HC
were around 30-40% of the limit. The engine is B18B1 from 94 Acura Integra
(non-VTEC). No internal mods. External mods are: Cold Air Intake, 4-1 DC
header, cat (installed last spring) & 2.50" SS tubing. The engine has
around 100K but is very clean inside (shiny) & it doesn't burn any oil
(always Mobil 1). I have a brand new O2 sensor (2 months old) & spark plugs
were replaced last summer w/NGK. One detail: my cat sits about 10-12" away
from the header. Would mounting the car right next to the header help?
>
> Now, can you suggest what to do to reduce NOx? Clean throttle body? How
about removing the crank ventilation hose from the intake tube? Replace the
spark plugs w/brand new ones? Will retarding of timing help to reduce NOx
(heard that version)?
>
> Please suggest me what would help, I only have 45 days to fix everything
(damn Jersey).
>
> Sorry that the post isn't very AutoX related (I did AutoX though).
>
> Thank you for any info/suggestions.
>
> Yuri Klepach
>
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