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View Full Version : Smog help!! 93 240sx stock


darkslide92
08-25-2011, 09:22 AM
Okay so I know there's a bunch of posts about this already, but most are pretty old, and maybe someone might have other ideas than I've read.*
The car: it's an all stock 1993 240sx. Has new egr and timing was adjusted back to stock (was previously retarded to help lower NO's). Exhaust is fully stock except for the fact that previous owner put two cats on the car to help pass. But i later found out it doesn't help so I'm planning on changing out to a stock downpipe.
Readings: smog tech said they were very strange lol. Measured HC at 10ppm for 15mph and 4ppm at 25mph (avg is [email protected] & [email protected]). CO's were both measured at 0%
Now the fun one. NO ppm max: [email protected] 15mph & [email protected] 25mph. Avg is in the mid to high 100's. But mine measured 1550 at 15mph and 171 at 25mph.
Thanks in advance for any help and ideas

Edwin562
08-25-2011, 09:34 AM
Car running hot??? you heating problems??? or either smog tech's machine is dumb... lol

is CEL on???

Edwin562
08-25-2011, 09:46 AM
try this link, there is a lot of good info on this...

High NOx Readings and What Are the Causes! (http://www.catalyticconverter.org/news/news_page.cfm?Key=catalytic_converter-&News=216)

darkslide92
08-25-2011, 03:15 PM
Thanks for the link. The only problem is I don't have a five gas analyzer to work with. And the car runs fine, no heating problems whatsoever, never ran hot even when drive it hard. And what is CEL?

Edwin562
08-25-2011, 03:29 PM
CEL= Check engine light

darkslide92
08-25-2011, 04:04 PM
Oh, no it's not on. Nothing seems mechanically wrong