Another emissions question...Again (Fwd)

["charles.slayman" <Charles.Slayman@domain.elided>]

Hi Fred,
	California Smog Test does not monitor NOx.  Just HC and CO.  My '89 Spider
flunked big time because I had a burned exhaust valve.  I didn't notice a
performance difference, but it showed up on a compression test.  Here are my
results BEFORE and AFTER a valve job.  

						BEFORE	AFTER
RPM						2330	2461
HC(PPM)	max allowable				140	140
	avg for passing vehicles		20	20
	actual					222	10
CO (%)	max allowable				1.00%	1.00%
	avg for passing vehicles		0.10%	0.10%
	actual					6.03%	0.08%
CO2 (%)	max allowable				NA	NA		
	avg for passing vehicles		NA	NA				
	actual					9.90%	13.50%
O2 (%)	max allowable				NA	NA		
	avg for passing vehicles		NA	NA				
	actual					1.90%	2.20%


Your numbers:

Item	Maximum		One month ago		Yesterday	Result

NOx	1438		2245			1871		FAIL
HC	187		229			186		Pass
CO	1.05		.67			.69		Pass
CO2	n/a		12.4			11.8		n/a
O2	n/a		2.1			3.4		n/a

	There not quite the same, but a properly running fuel injected engine should
pass the HC and CO numbers with a big margin.  Your numbers on HC and CO are
really marginal.  The high NOx has me puzzled because it typically means an
overly lean running engine.  But I don't know what happens when unburned gas
get into the catalytic converter.  Maybe Eric could tell us.
	At this point, I would ignore the NOx.  Do a compression test.  If there is >
20 lb variation from cylinder to cylinder, you might be looking at the start
of a burned valve.  For your low mileage, I would doubt rings would cause
compression variation if you do see it.

Good Luck,
Charlie S
'89 Spider

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