Nox challenges

[xxalexx at popd.ix.netcom.com]

If this is a cold start test, a problem would be CAT light off.
The headers are loosing to much heat.  Use all methods to 
retain heat: ceramic coatings, wraps, paints etc.
90% of emmisions or in 1st 60 sec. of test.
Check your cats for damaged honeycomb.
Install some small precats at collectors.
Use catalyst's with more loading.
Get some electric CATS.
Install a engine heat recovery system.
Try to get a realtime exhaust gas trace to see were Nox is max.
During ARB test ask for a cold start modal analysis for precon, this 
is usally less $ than a bag reading.  If dilute Nox is over 30 ppm 
for more than 3 sec. the car will fail. When car warm it should be < 
1 ppm at cruise.   You can also get similiar data with any one who
has a Nox analyzer, or go to Az. where they do a IM240
or ship it to east coast and I will see what I can do.
Alex
EPA-CARB recog. lab manager. 
> 
> I have a 1999 Infinity QX4 that I'm trying to get a set of headers
> emission legal (Smog Exempt) in California.  My first test failed
> because of high Nox.  This is determined by a formula they come up with
> that extends the results out to at least 50K at which point my Nox
> exceeded that limit.  (It would pass a standard street smog test no
> problem)  After some investigation I found an Infinity Service Bulletin
> that suggested adding a ground wire from the intake manifold to the
> righthand cylinder head.  Further diagnostics revealved a lazy or slow
> O2 sensor at which time I replaced all four.  After this I had the
> vehicle sniffed to verify any changes.  The Nox was down substantially.
> At this time I set all the SRT's and drove approx. 50 miles to make sure
> no DTC's popped up.  Off to the test lab again and failed again with
> high Nox.  This vehilce has no mods done to it.  Factory ECU. The only
> thing I can think of might cause this high Nox would be the design or
> flow of the tube off the header to the EGR on the engine.  Any ideas????
>