1996 BMW Z3 Smog Failure - California

1996 BMW Z3
111,000 MILES • 4 CYL • 2WD • MANUAL
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CDM_
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passed the following:

Visual
Functional
CO2
O2
HC
CO
(I tested extremely low for all of the above).

I failed NO (PPM):

15 mph (1982 RPM): 459 (allowed) 1065 (tested)
25 mph (1997 RPM): 746 (allowed) 278 (tested)

My first thought was cats, but the disparity between tested scores vs. tested RPM has me thinking something else. O2? ECV?

Thanks in advance for the input.

By the way, drove on the freeway at 3500 rpm for an hour prior to the test.
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Jul 7, 2009 at 8:18 PM
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DOCHAGERTY
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NOX can often be high due to carbon deposits, I have had success with high NOX cars by running water in the intake. It will clean out the carbon and lower the emissions. Do it slowly, it takes about a half gallon.
Jul 8, 2009 at 4:35 AM
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