164S Passes CA Smog Test

["Rich Lasner" <rlasner@domain.elided>]

I posted a couple of weeks back that my 1992 164S had failed CA smog
testing. I passed the 2500 RPM test, but failed the idle test. The
opinion of the tester was that the cat was bad. Tom Sahines' tip to
check the input and output temperatures at the cat with an infrared heat
sensing gun was a good one: The temperature exiting the cat was over 50
degrees cooler than the input temperature. Tom advised that the output
temperature should be at least 100 degrees hotter than the input. Time
for a new one.

I checked into getting the OEM part and found it was around $1100. I
also found that the OEM cat came integrated with a large resonator,
which I didn't want. My mechanic referred me to Mufflers Unlimited in
San Rafael, CA. They were able to fit a high-flow, 2-in, 2-out cat with
2" pipes (to replace the huge OEM resonator) for around $350, including
labor.

I took the car into the smog station this afternoon and passed easily.
Here are the dead cat/failed numbers, followed by the new cat/passed #s:

Old catalyst, 2500 RPM test: pass
HC (ppm)- 64	Max. allowable= 140
CO (%)- 0.20	Max. allowable= 1.00
CO2 (%)- 12.3
O2 (%)- 5.0
Old catalyst, idle test: fail
HC (ppm)- 166	Max. allowable= 120
CO (%)- 1.77	Max. allowable= 1.00
CO2 (%)- 11.3
O2 (%)- 4.9

New catalyst, 2500 RPM test: pass
HC (ppm)- 17	Max. allowable= 140
CO (%)- 0.02	Max. allowable= 1.00
CO2 (%)- 15.3
O2 (%)- 4.3
New catalyst, idle test: pass
HC (ppm)- 12	Max. allowable= 120
CO (%)- 0.01	Max. allowable= 1.00
CO2 (%)- 12.9
O2 (%)- 5.6

The high-flow cat without the resonator adds a deep rumble to the
already mean-sounding Stebro exhaust system I have on the car. The old
cat was clogged as well. The car feels more willing to pull with the
less restrictive converter, though I don't have any real data to
quantify that


Rich Lasner
92 164S
ARA
AROC
Mill Valley CA

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